IF YOU WOULD LIKE TO GET AN ACCOUNT, please write an
email to Administrator. User accounts are meant only to access repo
and report issues and/or generate pull requests.
This is a purpose-specific Git hosting for
BaseALT
projects. Thank you for your understanding!
Только зарегистрированные пользователи имеют доступ к сервису!
Для получения аккаунта, обратитесь к администратору.
With my new locking code dbench is so much faster that I tripped over a
transaction abort from ENOSPC. This turned out to be because
btrfs_del_dir_entries_in_log was checking for ret == -ENOSPC, but this
function sets err on error, and returns err. So instead of properly
marking the inode as needing a full commit, we were returning -ENOSPC
and aborting in __btrfs_unlink_inode. Fix this by checking the proper
variable so that we return the correct thing in the case of ENOSPC.
The ENOENT needs to be checked, because btrfs_lookup_dir_item_index()
can return -ENOENT if the dir item isn't in the tree log (which would
happen if we hadn't fsync'ed this guy). We actually handle that case in
__btrfs_unlink_inode, so it's an expected error to get back.
Fixes: 4a500fd178c8 ("Btrfs: Metadata ENOSPC handling for tree log")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add note and comment about ENOENT ]
Signed-off-by: David Sterba <dsterba@suse.com>
While logging an inode, at copy_items(), if we fail to lookup the checksums
for an extent we release the destination path, free the ins_data array and
then return immediately. However a previous iteration of the for loop may
have added checksums to the ordered_sums list, in which case we leak the
memory used by them.
So fix this by making sure we iterate the ordered_sums list and free all
its checksums before returning.
Fixes: 3650860b90cc2a ("Btrfs: remove almost all of the BUG()'s from tree-log.c")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The possibility of extents being shared (through clone and deduplication
operations) requires special care when logging data checksums, to avoid
having a log tree with different checksum items that cover ranges which
overlap (which resulted in missing checksums after replaying a log tree).
Such problems were fixed in the past by the following commits:
commit 40e046acbd2f ("Btrfs: fix missing data checksums after replaying a
log tree")
commit e289f03ea79b ("btrfs: fix corrupt log due to concurrent fsync of
inodes with shared extents")
Test case generic/588 exercises the scenario solved by the first commit
(purely sequential and deterministic) while test case generic/457 often
triggered the case fixed by the second commit (not deterministic, requires
specific timings under concurrency).
The problems were addressed by deleting, from the log tree, any existing
checksums before logging the new ones. And also by doing the deletion and
logging of the cheksums while locking the checksum range in an extent io
tree (root->log_csum_range), to deal with the case where we have concurrent
fsyncs against files with shared extents.
That however causes more contention on the leaves of a log tree where we
store checksums (and all the nodes in the paths leading to them), even
when we do not have shared extents, or all the shared extents were created
by past transactions. It also adds a bit of contention on the spin lock of
the log_csums_range extent io tree of the log root.
This change adds a 'last_reflink_trans' field to the inode to keep track
of the last transaction where a new extent was shared between inodes
(through clone and deduplication operations). It is updated for both the
source and destination inodes of reflink operations whenever a new extent
(created in the current transaction) becomes shared by the inodes. This
field is kept in memory only, not persisted in the inode item, similar
to other existing fields (last_unlink_trans, logged_trans).
When logging checksums for an extent, if the value of 'last_reflink_trans'
is smaller then the current transaction's generation/id, we skip locking
the extent range and deletion of checksums from the log tree, since we
know we do not have new shared extents. This reduces contention on the
log tree's leaves where checksums are stored.
The following script, which uses fio, was used to measure the impact of
this change:
$ cat test-fsync.sh
#!/bin/bash
DEV=/dev/sdk
MNT=/mnt/sdk
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-d single -m single"
if [ $# -ne 3 ]; then
echo "Use $0 NUM_JOBS FILE_SIZE FSYNC_FREQ"
exit 1
fi
NUM_JOBS=$1
FILE_SIZE=$2
FSYNC_FREQ=$3
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=write
fsync=$FSYNC_FREQ
fallocate=none
group_reporting=1
direct=0
bs=64k
ioengine=sync
size=$FILE_SIZE
directory=$MNT
numjobs=$NUM_JOBS
EOF
echo "Using config:"
echo
cat /tmp/fio-job.ini
echo
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
fio /tmp/fio-job.ini
umount $MNT
The tests were performed for different numbers of jobs, file sizes and
fsync frequency. A qemu VM using kvm was used, with 8 cores (the host has
12 cores, with cpu governance set to performance mode on all cores), 16GiB
of ram (the host has 64GiB) and using a NVMe device directly (without an
intermediary filesystem in the host). While running the tests, the host
was not used for anything else, to avoid disturbing the tests.
The obtained results were the following (the last line of fio's output was
pasted). Starting with 16 jobs is where a significant difference is
observable in this particular setup and hardware (differences highlighted
below). The very small differences for tests with less than 16 jobs are
possibly just noise and random.
**** 1 job, file size 1G, fsync frequency 1 ****
before this change:
WRITE: bw=23.8MiB/s (24.9MB/s), 23.8MiB/s-23.8MiB/s (24.9MB/s-24.9MB/s), io=1024MiB (1074MB), run=43075-43075msec
after this change:
WRITE: bw=24.4MiB/s (25.6MB/s), 24.4MiB/s-24.4MiB/s (25.6MB/s-25.6MB/s), io=1024MiB (1074MB), run=41938-41938msec
**** 2 jobs, file size 1G, fsync frequency 1 ****
before this change:
WRITE: bw=37.7MiB/s (39.5MB/s), 37.7MiB/s-37.7MiB/s (39.5MB/s-39.5MB/s), io=2048MiB (2147MB), run=54351-54351msec
after this change:
WRITE: bw=37.7MiB/s (39.5MB/s), 37.6MiB/s-37.6MiB/s (39.5MB/s-39.5MB/s), io=2048MiB (2147MB), run=54428-54428msec
**** 4 jobs, file size 1G, fsync frequency 1 ****
before this change:
WRITE: bw=67.5MiB/s (70.8MB/s), 67.5MiB/s-67.5MiB/s (70.8MB/s-70.8MB/s), io=4096MiB (4295MB), run=60669-60669msec
after this change:
WRITE: bw=68.6MiB/s (71.0MB/s), 68.6MiB/s-68.6MiB/s (71.0MB/s-71.0MB/s), io=4096MiB (4295MB), run=59678-59678msec
**** 8 jobs, file size 1G, fsync frequency 1 ****
before this change:
WRITE: bw=128MiB/s (134MB/s), 128MiB/s-128MiB/s (134MB/s-134MB/s), io=8192MiB (8590MB), run=64048-64048msec
after this change:
WRITE: bw=129MiB/s (135MB/s), 129MiB/s-129MiB/s (135MB/s-135MB/s), io=8192MiB (8590MB), run=63405-63405msec
**** 16 jobs, file size 1G, fsync frequency 1 ****
before this change:
WRITE: bw=78.5MiB/s (82.3MB/s), 78.5MiB/s-78.5MiB/s (82.3MB/s-82.3MB/s), io=16.0GiB (17.2GB), run=208676-208676msec
after this change:
WRITE: bw=110MiB/s (115MB/s), 110MiB/s-110MiB/s (115MB/s-115MB/s), io=16.0GiB (17.2GB), run=149295-149295msec
(+40.1% throughput, -28.5% runtime)
**** 32 jobs, file size 1G, fsync frequency 1 ****
before this change:
WRITE: bw=58.8MiB/s (61.7MB/s), 58.8MiB/s-58.8MiB/s (61.7MB/s-61.7MB/s), io=32.0GiB (34.4GB), run=557134-557134msec
after this change:
WRITE: bw=76.1MiB/s (79.8MB/s), 76.1MiB/s-76.1MiB/s (79.8MB/s-79.8MB/s), io=32.0GiB (34.4GB), run=430550-430550msec
(+29.4% throughput, -22.7% runtime)
**** 64 jobs, file size 512M, fsync frequency 1 ****
before this change:
WRITE: bw=65.8MiB/s (68.0MB/s), 65.8MiB/s-65.8MiB/s (68.0MB/s-68.0MB/s), io=32.0GiB (34.4GB), run=498055-498055msec
after this change:
WRITE: bw=85.1MiB/s (89.2MB/s), 85.1MiB/s-85.1MiB/s (89.2MB/s-89.2MB/s), io=32.0GiB (34.4GB), run=385116-385116msec
(+29.3% throughput, -22.7% runtime)
**** 128 jobs, file size 256M, fsync frequency 1 ****
before this change:
WRITE: bw=54.7MiB/s (57.3MB/s), 54.7MiB/s-54.7MiB/s (57.3MB/s-57.3MB/s), io=32.0GiB (34.4GB), run=599373-599373msec
after this change:
WRITE: bw=121MiB/s (126MB/s), 121MiB/s-121MiB/s (126MB/s-126MB/s), io=32.0GiB (34.4GB), run=271907-271907msec
(+121.2% throughput, -54.6% runtime)
**** 256 jobs, file size 256M, fsync frequency 1 ****
before this change:
WRITE: bw=69.2MiB/s (72.5MB/s), 69.2MiB/s-69.2MiB/s (72.5MB/s-72.5MB/s), io=64.0GiB (68.7GB), run=947536-947536msec
after this change:
WRITE: bw=121MiB/s (127MB/s), 121MiB/s-121MiB/s (127MB/s-127MB/s), io=64.0GiB (68.7GB), run=541916-541916msec
(+74.9% throughput, -42.8% runtime)
**** 512 jobs, file size 128M, fsync frequency 1 ****
before this change:
WRITE: bw=85.4MiB/s (89.5MB/s), 85.4MiB/s-85.4MiB/s (89.5MB/s-89.5MB/s), io=64.0GiB (68.7GB), run=767734-767734msec
after this change:
WRITE: bw=141MiB/s (147MB/s), 141MiB/s-141MiB/s (147MB/s-147MB/s), io=64.0GiB (68.7GB), run=466022-466022msec
(+65.1% throughput, -39.3% runtime)
**** 1024 jobs, file size 128M, fsync frequency 1 ****
before this change:
WRITE: bw=115MiB/s (120MB/s), 115MiB/s-115MiB/s (120MB/s-120MB/s), io=128GiB (137GB), run=1143775-1143775msec
after this change:
WRITE: bw=171MiB/s (180MB/s), 171MiB/s-171MiB/s (180MB/s-180MB/s), io=128GiB (137GB), run=764843-764843msec
(+48.7% throughput, -33.1% runtime)
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When syncing the log, we used to update the log root tree without holding
neither the log_mutex of the subvolume root nor the log_mutex of log root
tree.
We used to have two critical sections delimited by the log_mutex of the
log root tree, so in the first one we incremented the log_writers of the
log root tree and on the second one we decremented it and waited for the
log_writers counter to go down to zero. This was because the update of
the log root tree happened between the two critical sections.
The use of two critical sections allowed a little bit more of parallelism
and required the use of the log_writers counter, necessary to make sure
we didn't miss any log root tree update when we have multiple tasks trying
to sync the log in parallel.
However after commit 06989c799f0481 ("Btrfs: fix race updating log root
item during fsync") the log root tree update was moved into a critical
section delimited by the subvolume's log_mutex. Later another commit
moved the log tree update from that critical section into the second
critical section delimited by the log_mutex of the log root tree. Both
commits addressed different bugs.
The end result is that the first critical section delimited by the
log_mutex of the log root tree became pointless, since there's nothing
done between it and the second critical section, we just have an unlock
of the log_mutex followed by a lock operation. This means we can merge
both critical sections, as the first one does almost nothing now, and we
can stop using the log_writers counter of the log root tree, which was
incremented in the first critical section and decremented in the second
criticial section, used to make sure no one in the second critical section
started writeback of the log root tree before some other task updated it.
So just remove the mutex_unlock() followed by mutex_lock() of the log root
tree, as well as the use of the log_writers counter for the log root tree.
This patch is part of a series that has the following patches:
1/4 btrfs: only commit the delayed inode when doing a full fsync
2/4 btrfs: only commit delayed items at fsync if we are logging a directory
3/4 btrfs: stop incremening log_batch for the log root tree when syncing log
4/4 btrfs: remove no longer needed use of log_writers for the log root tree
After the entire patchset applied I saw about 12% decrease on max latency
reported by dbench. The test was done on a qemu vm, with 8 cores, 16Gb of
ram, using kvm and using a raw NVMe device directly (no intermediary fs on
the host). The test was invoked like the following:
mkfs.btrfs -f /dev/sdk
mount -o ssd -o nospace_cache /dev/sdk /mnt/sdk
dbench -D /mnt/sdk -t 300 8
umount /mnt/dsk
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We are incrementing the log_batch atomic counter of the root log tree but
we never use that counter, it's used only for the log trees of subvolume
roots. We started doing it when we moved the log_batch and log_write
counters from the global, per fs, btrfs_fs_info structure, into the
btrfs_root structure in commit 7237f1833601dc ("Btrfs: fix tree logs
parallel sync").
So just stop doing it for the log root tree and add a comment over the
field declaration so inform it's used only for log trees of subvolume
roots.
This patch is part of a series that has the following patches:
1/4 btrfs: only commit the delayed inode when doing a full fsync
2/4 btrfs: only commit delayed items at fsync if we are logging a directory
3/4 btrfs: stop incremening log_batch for the log root tree when syncing log
4/4 btrfs: remove no longer needed use of log_writers for the log root tree
After the entire patchset applied I saw about 12% decrease on max latency
reported by dbench. The test was done on a qemu vm, with 8 cores, 16Gb of
ram, using kvm and using a raw NVMe device directly (no intermediary fs on
the host). The test was invoked like the following:
mkfs.btrfs -f /dev/sdk
mount -o ssd -o nospace_cache /dev/sdk /mnt/sdk
dbench -D /mnt/sdk -t 300 8
umount /mnt/dsk
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When logging an inode we are committing its delayed items if either the
inode is a directory or if it is a new inode, created in the current
transaction.
We need to do it for directories, since new directory indexes are stored
as delayed items of the inode and when logging a directory we need to be
able to access all indexes from the fs/subvolume tree in order to figure
out which index ranges need to be logged.
However for new inodes that are not directories, we do not need to do it
because the only type of delayed item they can have is the inode item, and
we are guaranteed to always log an up to date version of the inode item:
*) for a full fsync we do it by committing the delayed inode and then
copying the item from the fs/subvolume tree with
copy_inode_items_to_log();
*) for a fast fsync we always log the inode item based on the contents of
the in-memory struct btrfs_inode. We guarantee this is always done since
commit e4545de5b035c7 ("Btrfs: fix fsync data loss after append write").
So stop running delayed items for a new inodes that are not directories,
since that forces committing the delayed inode into the fs/subvolume tree,
wasting time and adding contention to the tree when a full fsync is not
required. We will only do it in case a fast fsync is needed.
This patch is part of a series that has the following patches:
1/4 btrfs: only commit the delayed inode when doing a full fsync
2/4 btrfs: only commit delayed items at fsync if we are logging a directory
3/4 btrfs: stop incremening log_batch for the log root tree when syncing log
4/4 btrfs: remove no longer needed use of log_writers for the log root tree
After the entire patchset applied I saw about 12% decrease on max latency
reported by dbench. The test was done on a qemu vm, with 8 cores, 16Gb of
ram, using kvm and using a raw NVMe device directly (no intermediary fs on
the host). The test was invoked like the following:
mkfs.btrfs -f /dev/sdk
mount -o ssd -o nospace_cache /dev/sdk /mnt/sdk
dbench -D /mnt/sdk -t 300 8
umount /mnt/dsk
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit 2c2c452b0cafdc ("Btrfs: fix fsync when extend references are added
to an inode") forced a commit of the delayed inode when logging an inode
in order to ensure we would end up logging the inode item during a full
fsync. By committing the delayed inode, we updated the inode item in the
fs/subvolume tree and then later when copying items from leafs modified in
the current transaction into the log tree (with copy_inode_items_to_log())
we ended up copying the inode item from the fs/subvolume tree into the log
tree. Logging an up to date version of the inode item is required to make
sure at log replay time we get the link count fixup triggered among other
things (replay xattr deletes, etc). The test case generic/040 from fstests
exercises the bug which that commit fixed.
However for a fast fsync we don't need to commit the delayed inode because
we always log an up to date version of the inode item based on the struct
btrfs_inode we have in-memory. We started doing this for fast fsyncs since
commit e4545de5b035c7 ("Btrfs: fix fsync data loss after append write").
So just stop committing the delayed inode if we are doing a fast fsync,
we are only wasting time and adding contention on fs/subvolume tree.
This patch is part of a series that has the following patches:
1/4 btrfs: only commit the delayed inode when doing a full fsync
2/4 btrfs: only commit delayed items at fsync if we are logging a directory
3/4 btrfs: stop incremening log_batch for the log root tree when syncing log
4/4 btrfs: remove no longer needed use of log_writers for the log root tree
After the entire patchset applied I saw about 12% decrease on max latency
reported by dbench. The test was done on a qemu vm, with 8 cores, 16Gb of
ram, using kvm and using a raw NVMe device directly (no intermediary fs on
the host). The test was invoked like the following:
mkfs.btrfs -f /dev/sdk
mount -o ssd -o nospace_cache /dev/sdk /mnt/sdk
dbench -D /mnt/sdk -t 300 8
umount /mnt/dsk
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It has only 4 uses of a vfs_inode for inode_sub_bytes but unifies the
interface with the non __ prefixed version. Will also makes converting
its callers to btrfs_inode easier.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This brings back an optimization that commit e678934cbe5f02 ("btrfs:
Remove unnecessary check from join_running_log_trans") removed, but in
a different form. So it's almost equivalent to a revert.
That commit removed an optimization where we avoid locking a root's
log_mutex when there is no log tree created in the current transaction.
The affected code path is triggered through unlink operations.
That commit was based on the assumption that the optimization was not
necessary because we used to have the following checks when the patch
was authored:
int btrfs_del_dir_entries_in_log(...)
{
(...)
if (dir->logged_trans < trans->transid)
return 0;
ret = join_running_log_trans(root);
(...)
}
int btrfs_del_inode_ref_in_log(...)
{
(...)
if (inode->logged_trans < trans->transid)
return 0;
ret = join_running_log_trans(root);
(...)
}
However before that patch was merged, another patch was merged first which
replaced those checks because they were buggy.
That other patch corresponds to commit 803f0f64d17769 ("Btrfs: fix fsync
not persisting dentry deletions due to inode evictions"). The assumption
that if the logged_trans field of an inode had a smaller value then the
current transaction's generation (transid) meant that the inode was not
logged in the current transaction was only correct if the inode was not
evicted and reloaded in the current transaction. So the corresponding bug
fix changed those checks and replaced them with the following helper
function:
static bool inode_logged(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode)
{
if (inode->logged_trans == trans->transid)
return true;
if (inode->last_trans == trans->transid &&
test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags) &&
!test_bit(BTRFS_FS_LOG_RECOVERING, &trans->fs_info->flags))
return true;
return false;
}
So if we have a subvolume without a log tree in the current transaction
(because we had no fsyncs), every time we unlink an inode we can end up
trying to lock the log_mutex of the root through join_running_log_trans()
twice, once for the inode being unlinked (by btrfs_del_inode_ref_in_log())
and once for the parent directory (with btrfs_del_dir_entries_in_log()).
This means if we have several unlink operations happening in parallel for
inodes in the same subvolume, and the those inodes and/or their parent
inode were changed in the current transaction, we end up having a lot of
contention on the log_mutex.
The test robots from intel reported a -30.7% performance regression for
a REAIM test after commit e678934cbe5f02 ("btrfs: Remove unnecessary check
from join_running_log_trans").
So just bring back the optimization to join_running_log_trans() where we
check first if a log root exists before trying to lock the log_mutex. This
is done by checking for a bit that is set on the root when a log tree is
created and removed when a log tree is freed (at transaction commit time).
Commit e678934cbe5f02 ("btrfs: Remove unnecessary check from
join_running_log_trans") was merged in the 5.4 merge window while commit
803f0f64d17769 ("Btrfs: fix fsync not persisting dentry deletions due to
inode evictions") was merged in the 5.3 merge window. But the first
commit was actually authored before the second commit (May 23 2019 vs
June 19 2019).
Reported-by: kernel test robot <rong.a.chen@intel.com>
Link: https://lore.kernel.org/lkml/20200611090233.GL12456@shao2-debian/
Fixes: e678934cbe5f02 ("btrfs: Remove unnecessary check from join_running_log_trans")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we have extents shared amongst different inodes in the same subvolume,
if we fsync them in parallel we can end up with checksum items in the log
tree that represent ranges which overlap.
For example, consider we have inodes A and B, both sharing an extent that
covers the logical range from X to X + 64KiB:
1) Task A starts an fsync on inode A;
2) Task B starts an fsync on inode B;
3) Task A calls btrfs_csum_file_blocks(), and the first search in the
log tree, through btrfs_lookup_csum(), returns -EFBIG because it
finds an existing checksum item that covers the range from X - 64KiB
to X;
4) Task A checks that the checksum item has not reached the maximum
possible size (MAX_CSUM_ITEMS) and then releases the search path
before it does another path search for insertion (through a direct
call to btrfs_search_slot());
5) As soon as task A releases the path and before it does the search
for insertion, task B calls btrfs_csum_file_blocks() and gets -EFBIG
too, because there is an existing checksum item that has an end
offset that matches the start offset (X) of the checksum range we want
to log;
6) Task B releases the path;
7) Task A does the path search for insertion (through btrfs_search_slot())
and then verifies that the checksum item that ends at offset X still
exists and extends its size to insert the checksums for the range from
X to X + 64KiB;
8) Task A releases the path and returns from btrfs_csum_file_blocks(),
having inserted the checksums into an existing checksum item that got
its size extended. At this point we have one checksum item in the log
tree that covers the logical range from X - 64KiB to X + 64KiB;
9) Task B now does a search for insertion using btrfs_search_slot() too,
but it finds that the previous checksum item no longer ends at the
offset X, it now ends at an of offset X + 64KiB, so it leaves that item
untouched.
Then it releases the path and calls btrfs_insert_empty_item()
that inserts a checksum item with a key offset corresponding to X and
a size for inserting a single checksum (4 bytes in case of crc32c).
Subsequent iterations end up extending this new checksum item so that
it contains the checksums for the range from X to X + 64KiB.
So after task B returns from btrfs_csum_file_blocks() we end up with
two checksum items in the log tree that have overlapping ranges, one
for the range from X - 64KiB to X + 64KiB, and another for the range
from X to X + 64KiB.
Having checksum items that represent ranges which overlap, regardless of
being in the log tree or in the chekcsums tree, can lead to problems where
checksums for a file range end up not being found. This type of problem
has happened a few times in the past and the following commits fixed them
and explain in detail why having checksum items with overlapping ranges is
problematic:
27b9a8122ff71a "Btrfs: fix csum tree corruption, duplicate and outdated checksums"
b84b8390d6009c "Btrfs: fix file read corruption after extent cloning and fsync"
40e046acbd2f36 "Btrfs: fix missing data checksums after replaying a log tree"
Since this specific instance of the problem can only happen when logging
inodes, because it is the only case where concurrent attempts to insert
checksums for the same range can happen, fix the issue by using an extent
io tree as a range lock to serialize checksum insertion during inode
logging.
This issue could often be reproduced by the test case generic/457 from
fstests. When it happens it produces the following trace:
BTRFS critical (device dm-0): corrupt leaf: root=18446744073709551610 block=30625792 slot=42, csum end range (15020032) goes beyond the start range (15015936) of the next csum item
BTRFS info (device dm-0): leaf 30625792 gen 7 total ptrs 49 free space 2402 owner 18446744073709551610
BTRFS info (device dm-0): refs 1 lock (w:0 r:0 bw:0 br:0 sw:0 sr:0) lock_owner 0 current 15884
item 0 key (18446744073709551606 128 13979648) itemoff 3991 itemsize 4
item 1 key (18446744073709551606 128 13983744) itemoff 3987 itemsize 4
item 2 key (18446744073709551606 128 13987840) itemoff 3983 itemsize 4
item 3 key (18446744073709551606 128 13991936) itemoff 3979 itemsize 4
item 4 key (18446744073709551606 128 13996032) itemoff 3975 itemsize 4
item 5 key (18446744073709551606 128 14000128) itemoff 3971 itemsize 4
(...)
BTRFS error (device dm-0): block=30625792 write time tree block corruption detected
------------[ cut here ]------------
WARNING: CPU: 1 PID: 15884 at fs/btrfs/disk-io.c:539 btree_csum_one_bio+0x268/0x2d0 [btrfs]
Modules linked in: btrfs dm_thin_pool ...
CPU: 1 PID: 15884 Comm: fsx Tainted: G W 5.6.0-rc7-btrfs-next-58 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:btree_csum_one_bio+0x268/0x2d0 [btrfs]
Code: c7 c7 ...
RSP: 0018:ffffbb0109e6f8e0 EFLAGS: 00010296
RAX: 0000000000000000 RBX: ffffe1c0847b6080 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffaa963988 RDI: 0000000000000001
RBP: ffff956a4f4d2000 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000526 R11: 0000000000000000 R12: ffff956a5cd28bb0
R13: 0000000000000000 R14: ffff956a649c9388 R15: 000000011ed82000
FS: 00007fb419959e80(0000) GS:ffff956a7aa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000fe6d54 CR3: 0000000138696005 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btree_submit_bio_hook+0x67/0xc0 [btrfs]
submit_one_bio+0x31/0x50 [btrfs]
btree_write_cache_pages+0x2db/0x4b0 [btrfs]
? __filemap_fdatawrite_range+0xb1/0x110
do_writepages+0x23/0x80
__filemap_fdatawrite_range+0xd2/0x110
btrfs_write_marked_extents+0x15e/0x180 [btrfs]
btrfs_sync_log+0x206/0x10a0 [btrfs]
? kmem_cache_free+0x315/0x3b0
? btrfs_log_inode+0x1e8/0xf90 [btrfs]
? __mutex_unlock_slowpath+0x45/0x2a0
? lockref_put_or_lock+0x9/0x30
? dput+0x2d/0x580
? dput+0xb5/0x580
? btrfs_sync_file+0x464/0x4d0 [btrfs]
btrfs_sync_file+0x464/0x4d0 [btrfs]
do_fsync+0x38/0x60
__x64_sys_fsync+0x10/0x20
do_syscall_64+0x5c/0x280
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fb41953a6d0
Code: 48 3d ...
RSP: 002b:00007ffcc86bd218 EFLAGS: 00000246 ORIG_RAX: 000000000000004a
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007fb41953a6d0
RDX: 0000000000000009 RSI: 0000000000040000 RDI: 0000000000000003
RBP: 0000000000040000 R08: 0000000000000001 R09: 0000000000000009
R10: 0000000000000064 R11: 0000000000000246 R12: 0000556cf4b2c060
R13: 0000000000000100 R14: 0000000000000000 R15: 0000556cf322b420
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffffa96bdedf>] copy_process+0x74f/0x2020
softirqs last enabled at (0): [<ffffffffa96bdedf>] copy_process+0x74f/0x2020
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace d543fc76f5ad7fd8 ]---
In that trace the tree checker detected the overlapping checksum items at
the time when we triggered writeback for the log tree when syncing the
log.
Another trace that can happen is due to BUG_ON() when deleting checksum
items while logging an inode:
BTRFS critical (device dm-0): slot 81 key (18446744073709551606 128 13635584) new key (18446744073709551606 128 13635584)
BTRFS info (device dm-0): leaf 30949376 gen 7 total ptrs 98 free space 8527 owner 18446744073709551610
BTRFS info (device dm-0): refs 4 lock (w:1 r:0 bw:0 br:0 sw:1 sr:0) lock_owner 13473 current 13473
item 0 key (257 1 0) itemoff 16123 itemsize 160
inode generation 7 size 262144 mode 100600
item 1 key (257 12 256) itemoff 16103 itemsize 20
item 2 key (257 108 0) itemoff 16050 itemsize 53
extent data disk bytenr 13631488 nr 4096
extent data offset 0 nr 131072 ram 131072
(...)
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.c:3153!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
CPU: 1 PID: 13473 Comm: fsx Not tainted 5.6.0-rc7-btrfs-next-58 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_set_item_key_safe+0x1ea/0x270 [btrfs]
Code: 0f b6 ...
RSP: 0018:ffff95e3889179d0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000051 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffb7763988 RDI: 0000000000000001
RBP: fffffffffffffff6 R08: 0000000000000000 R09: 0000000000000001
R10: 00000000000009ef R11: 0000000000000000 R12: ffff8912a8ba5a08
R13: ffff95e388917a06 R14: ffff89138dcf68c8 R15: ffff95e388917ace
FS: 00007fe587084e80(0000) GS:ffff8913baa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe587091000 CR3: 0000000126dac005 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_del_csums+0x2f4/0x540 [btrfs]
copy_items+0x4b5/0x560 [btrfs]
btrfs_log_inode+0x910/0xf90 [btrfs]
btrfs_log_inode_parent+0x2a0/0xe40 [btrfs]
? dget_parent+0x5/0x370
btrfs_log_dentry_safe+0x4a/0x70 [btrfs]
btrfs_sync_file+0x42b/0x4d0 [btrfs]
__x64_sys_msync+0x199/0x200
do_syscall_64+0x5c/0x280
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fe586c65760
Code: 00 f7 ...
RSP: 002b:00007ffe250f98b8 EFLAGS: 00000246 ORIG_RAX: 000000000000001a
RAX: ffffffffffffffda RBX: 00000000000040e1 RCX: 00007fe586c65760
RDX: 0000000000000004 RSI: 0000000000006b51 RDI: 00007fe58708b000
RBP: 0000000000006a70 R08: 0000000000000003 R09: 00007fe58700cb61
R10: 0000000000000100 R11: 0000000000000246 R12: 00000000000000e1
R13: 00007fe58708b000 R14: 0000000000006b51 R15: 0000558de021a420
Modules linked in: dm_log_writes ...
---[ end trace c92a7f447a8515f5 ]---
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The inode lookup starting at btrfs_iget takes the full location key,
while only the objectid is used to match the inode, because the lookup
happens inside the given root thus the inode number is unique.
The entire location key is properly set up in btrfs_init_locked_inode.
Simplify the helpers and pass only inode number, renaming it to 'ino'
instead of 'objectid'. This allows to remove temporary variables key,
saving some stack space.
Signed-off-by: David Sterba <dsterba@suse.com>
The main function to lookup a root by its id btrfs_get_fs_root takes the
whole key, while only using the objectid. The value of offset is preset
to (u64)-1 but not actually used until btrfs_find_root that does the
actual search.
Switch btrfs_get_fs_root to use only objectid and remove all local
variables that existed just for the lookup. The actual key for search is
set up in btrfs_get_fs_root, reusing another key variable.
Signed-off-by: David Sterba <dsterba@suse.com>
The set/get token is supposed to cache the last page that was accessed
so it speeds up subsequential access to the eb. It does not make sense
to use that for just one change, which is the case of inode size in
overwrite_item.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that all set/get helpers use the eb from the token, we don't need to
pass it to many btrfs_token_*/btrfs_set_token_* helpers, saving some
stack space.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At btrfs_log_prealloc_extents() we are checking if copy_items() returns a
value greater than 0. That used to happen in the past to signal the caller
that the path given to it was released and reused for other searches, but
as of commit 0e56315ca147b3 ("Btrfs: fix missing hole after hole punching
and fsync when using NO_HOLES"), the copy_items() function does not have
that behaviour anymore and always returns 0 or a negative value. So just
remove that check at btrfs_log_prealloc_extents(), which the previously
mentioned commit forgot to remove.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All callers pass the eb::level so we can get read it directly inside the
btrfs_bin_search and key_search.
This is inspired by the work of Marek in U-boot.
CC: Marek Behun <marek.behun@nic.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we have an inode with a prealloc extent that starts at an offset
lower than the i_size and there is another prealloc extent that starts at
an offset beyond i_size, we can end up losing part of the first prealloc
extent (the part that starts at i_size) and have an implicit hole if we
fsync the file and then have a power failure.
Consider the following example with comments explaining how and why it
happens.
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
# Create our test file with 2 consecutive prealloc extents, each with a
# size of 128Kb, and covering the range from 0 to 256Kb, with a file
# size of 0.
$ xfs_io -f -c "falloc -k 0 128K" /mnt/foo
$ xfs_io -c "falloc -k 128K 128K" /mnt/foo
# Fsync the file to record both extents in the log tree.
$ xfs_io -c "fsync" /mnt/foo
# Now do a redudant extent allocation for the range from 0 to 64Kb.
# This will merely increase the file size from 0 to 64Kb. Instead we
# could also do a truncate to set the file size to 64Kb.
$ xfs_io -c "falloc 0 64K" /mnt/foo
# Fsync the file, so we update the inode item in the log tree with the
# new file size (64Kb). This also ends up setting the number of bytes
# for the first prealloc extent to 64Kb. This is done by the truncation
# at btrfs_log_prealloc_extents().
# This means that if a power failure happens after this, a write into
# the file range 64Kb to 128Kb will not use the prealloc extent and
# will result in allocation of a new extent.
$ xfs_io -c "fsync" /mnt/foo
# Now set the file size to 256K with a truncate and then fsync the file.
# Since no changes happened to the extents, the fsync only updates the
# i_size in the inode item at the log tree. This results in an implicit
# hole for the file range from 64Kb to 128Kb, something which fsck will
# complain when not using the NO_HOLES feature if we replay the log
# after a power failure.
$ xfs_io -c "truncate 256K" -c "fsync" /mnt/foo
So instead of always truncating the log to the inode's current i_size at
btrfs_log_prealloc_extents(), check first if there's a prealloc extent
that starts at an offset lower than the i_size and with a length that
crosses the i_size - if there is one, just make sure we truncate to a
size that corresponds to the end offset of that prealloc extent, so
that we don't lose the part of that extent that starts at i_size if a
power failure happens.
A test case for fstests follows soon.
Fixes: 31d11b83b96f ("Btrfs: fix duplicate extents after fsync of file with prealloc extents")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is a revert of commit 0a8068a3dd4294 ("btrfs: make ranged full
fsyncs more efficient"), with updated comment in btrfs_sync_file.
Commit 0a8068a3dd4294 ("btrfs: make ranged full fsyncs more efficient")
made full fsyncs operate on the given range only as it assumed it was safe
when using the NO_HOLES feature, since the hole detection was simplified
some time ago and no longer was a source for races with ordered extent
completion of adjacent file ranges.
However it's still not safe to have a full fsync only operate on the given
range, because extent maps for new extents might not be present in memory
due to inode eviction or extent cloning. Consider the following example:
1) We are currently at transaction N;
2) We write to the file range [0, 1MiB);
3) Writeback finishes for the whole range and ordered extents complete,
while we are still at transaction N;
4) The inode is evicted;
5) We open the file for writing, causing the inode to be loaded to
memory again, which sets the 'full sync' bit on its flags. At this
point the inode's list of modified extent maps is empty (figuring
out which extents were created in the current transaction and were
not yet logged by an fsync is expensive, that's why we set the
'full sync' bit when loading an inode);
6) We write to the file range [512KiB, 768KiB);
7) We do a ranged fsync (such as msync()) for file range [512KiB, 768KiB).
This correctly flushes this range and logs its extent into the log
tree. When the writeback started an extent map for range [512KiB, 768KiB)
was added to the inode's list of modified extents, and when the fsync()
finishes logging it removes that extent map from the list of modified
extent maps. This fsync also clears the 'full sync' bit;
8) We do a regular fsync() (full ranged). This fsync() ends up doing
nothing because the inode's list of modified extents is empty and
no other changes happened since the previous ranged fsync(), so
it just returns success (0) and we end up never logging extents for
the file ranges [0, 512KiB) and [768KiB, 1MiB).
Another scenario where this can happen is if we replace steps 2 to 4 with
cloning from another file into our test file, as that sets the 'full sync'
bit in our inode's flags and does not populate its list of modified extent
maps.
This was causing test case generic/457 to fail sporadically when using the
NO_HOLES feature, as it exercised this later case where the inode has the
'full sync' bit set and has no extent maps in memory to represent the new
extents due to extent cloning.
Fix this by reverting commit 0a8068a3dd4294 ("btrfs: make ranged full fsyncs
more efficient") since there is no easy way to work around it.
Fixes: 0a8068a3dd4294 ("btrfs: make ranged full fsyncs more efficient")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are a few different ways to free roots, either you allocated them
yourself and you just do
free_extent_buffer(root->node);
free_extent_buffer(root->commit_node);
btrfs_put_root(root);
Which is the pattern for log roots. Or for snapshots/subvolumes that
are being dropped you simply call btrfs_free_fs_root() which does all
the cleanup for you.
Unify this all into btrfs_put_root(), so that we don't free up things
associated with the root until the last reference is dropped. This
makes the root freeing code much more significant.
The only caveat is at close_ctree() time we have to free the extent
buffers for all of our main roots (extent_root, chunk_root, etc) because
we have to drop the btree_inode and we'll run into issues if we hold
onto those nodes until ->kill_sb() time. This will be addressed in the
future when we kill the btree_inode.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit 0c713cbab6200b ("Btrfs: fix race between ranged fsync and writeback
of adjacent ranges") fixed a bug where we could end up with file extent
items in a log tree that represent file ranges that overlap due to a race
between the hole detection of a ranged full fsync and writeback for a
different file range.
The problem was solved by forcing any ranged full fsync to become a
non-ranged full fsync - setting the range start to 0 and the end offset to
LLONG_MAX. This was a simple solution because the code that detected and
marked holes was very complex, it used to be done at copy_items() and
implied several searches on the fs/subvolume tree. The drawback of that
solution was that we started to flush delalloc for the entire file and
wait for all the ordered extents to complete for ranged full fsyncs
(including ordered extents covering ranges completely outside the given
range). Fortunatelly ranged full fsyncs are not the most common case
(hopefully for most workloads).
However a later fix for detecting and marking holes was made by commit
0e56315ca147b3 ("Btrfs: fix missing hole after hole punching and fsync
when using NO_HOLES") and it simplified a lot the detection of holes,
and now copy_items() no longer does it and we do it in a much more simple
way at btrfs_log_holes().
This makes it now possible to simply make the code that detects holes to
operate only on the initial range and no longer need to operate on the
whole file, while also avoiding the need to flush delalloc for the entire
file and wait for ordered extents that cover ranges that don't overlap the
given range.
Another special care is that we must skip file extent items that fall
entirely outside the fsync range when copying inode items from the
fs/subvolume tree into the log tree - this is to avoid races with ordered
extent completion for extents falling outside the fsync range, which could
cause us to end up with file extent items in the log tree that have
overlapping ranges - for example if the fsync range is [1Mb, 2Mb], when
we copy inode items we could copy an extent item for the range [0, 512K],
then release the search path and before moving to the next leaf, an
ordered extent for a range of [256Kb, 512Kb] completes - this would
cause us to copy the new extent item for range [256Kb, 512Kb] into the
log tree after we have copied one for the range [0, 512Kb] - the extents
overlap, resulting in a corruption.
So this change just does these steps:
1) When the NO_HOLES feature is enabled it leaves the initial range
intact - no longer sets it to [0, LLONG_MAX] when the full sync bit
is set in the inode. If NO_HOLES is not enabled, always set the range
to a full, just like before this change, to avoid missing file extent
items representing holes after replaying the log (for both full and
fast fsyncs);
2) Make the hole detection code to operate only on the fsync range;
3) Make the code that copies items from the fs/subvolume tree to skip
copying file extent items that cover a range completely outside the
range of the fsync.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function btrfs_log_inode() is quite large and so is its loop which
iterates the inode items from the fs/subvolume tree and copies them into
a log tree. Because this is a large loop inside a very large function
and because an upcoming patch in this series needs to add some more logic
inside that loop, move the loop into a helper function to make it a bit
more manageable.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Getting the end offset for a file extent item requires a bit of code since
the extent can be either inline or regular/prealloc. There are some places
all over the code base that open code this logic and in another patch
later in this series it will be needed again. Therefore encapsulate this
logic in a helper function and use it.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Preparation for refactoring pinned extents tracking.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_pin_reserved_extent is now only called with a valid transaction so
exploit the fact to take a transaction. This is preparation for tracking
pinned extents on a per-transaction basis.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Calling btrfs_pin_reserved_extent makes sense only with a valid
transaction since pinned extents are processed from transaction commit
in btrfs_finish_extent_commit. In case of error it's sufficient to
adjust the reserved counter to account for log tree extents allocated in
the last transaction.
This commit moves btrfs_pin_reserved_extent to be called only with valid
transaction handle and otherwise uses the newly introduced
unaccount_log_buffer to adjust "reserved". If this is not done if a
failure occurs before transaction is committed WARN_ON are going to be
triggered on unmount. This was especially pronounced with generic/475
test.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This function correctly adjusts the reserved bytes occupied by a log
tree extent buffer. It will be used instead of calling
btrfs_pin_reserved_extent.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We are now using these for all roots, rename them to btrfs_put_root()
and btrfs_grab_root();
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that all callers of btrfs_get_fs_root are subsequently calling
btrfs_grab_fs_root and handling dropping the ref when they are done
appropriately, go ahead and push btrfs_grab_fs_root up into
btrfs_get_fs_root.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we are going to track leaked roots we need to free them all the same
way, so don't kfree() roots directly, use btrfs_put_fs_root.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We replay the log into arbitrary fs roots, hold a ref on the root while
we're doing this.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All this does is call btrfs_get_fs_root() with check_ref == true. Just
use btrfs_get_fs_root() so we don't have a bunch of different helpers
that do the same thing.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Tree-log uses btrfs_read_fs_root to load its log, but this just calls
btrfs_read_tree_root. We don't save the log roots in our root cache, so
just export this helper and use it in the logging code.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We want to use this everywhere we modify the file extent items
permanently. These include:
1) Inserting new file extents for writes and prealloc extents.
2) Truncating inode items.
3) btrfs_cont_expand().
4) Insert inline extents.
5) Insert new extents from log replay.
6) Insert a new extent for clone, as it could be past i_size.
7) Hole punching
For hole punching in particular it might seem it's not necessary because
anybody extending would use btrfs_cont_expand, however there is a corner
that still can give us trouble. Start with an empty file and
fallocate KEEP_SIZE 1M-2M
We now have a 0 length file, and a hole file extent from 0-1M, and a
prealloc extent from 1M-2M. Now
punch 1M-1.5M
Because this is past i_size we have
[HOLE EXTENT][ NOTHING ][PREALLOC]
[0 1M][1M 1.5M][1.5M 2M]
with an i_size of 0. Now if we pwrite 0-1.5M we'll increas our i_size
to 1.5M, but our disk_i_size is still 0 until the ordered extent
completes.
However if we now immediately truncate 2M on the file we'll just call
btrfs_cont_expand(inode, 1.5M, 2M), since our old i_size is 1.5M. If we
commit the transaction here and crash we'll expose the gap.
To fix this we need to clear the file extent mapping for the range that
we punched but didn't insert a corresponding file extent for. This will
mean the truncate will only get an disk_i_size set to 1M if we crash
before the finish ordered io happens.
I've written an xfstest to reproduce the problem and validate this fix.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Recently fsstress (from fstests) sporadically started to trigger an
infinite loop during fsync operations. This turned out to be because
support for the rename exchange and whiteout operations was added to
fsstress in fstests. These operations, unlike any others in fsstress,
cause file names to be reused, whence triggering this issue. However
it's not necessary to use rename exchange and rename whiteout operations
trigger this issue, simple rename operations and file creations are
enough to trigger the issue.
The issue boils down to when we are logging inodes that conflict (that
had the name of any inode we need to log during the fsync operation), we
keep logging them even if they were already logged before, and after
that we check if there's any other inode that conflicts with them and
then add it again to the list of inodes to log. Skipping already logged
inodes fixes the issue.
Consider the following example:
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ mkdir /mnt/testdir # inode 257
$ touch /mnt/testdir/zz # inode 258
$ ln /mnt/testdir/zz /mnt/testdir/zz_link
$ touch /mnt/testdir/a # inode 259
$ sync
# The following 3 renames achieve the same result as a rename exchange
# operation (<rename_exchange> /mnt/testdir/zz_link to /mnt/testdir/a).
$ mv /mnt/testdir/a /mnt/testdir/a/tmp
$ mv /mnt/testdir/zz_link /mnt/testdir/a
$ mv /mnt/testdir/a/tmp /mnt/testdir/zz_link
# The following rename and file creation give the same result as a
# rename whiteout operation (<rename_whiteout> zz to a2).
$ mv /mnt/testdir/zz /mnt/testdir/a2
$ touch /mnt/testdir/zz # inode 260
$ xfs_io -c fsync /mnt/testdir/zz
--> results in the infinite loop
The following steps happen:
1) When logging inode 260, we find that its reference named "zz" was
used by inode 258 in the previous transaction (through the commit
root), so inode 258 is added to the list of conflicting indoes that
need to be logged;
2) After logging inode 258, we find that its reference named "a" was
used by inode 259 in the previous transaction, and therefore we add
inode 259 to the list of conflicting inodes to be logged;
3) After logging inode 259, we find that its reference named "zz_link"
was used by inode 258 in the previous transaction - we add inode 258
to the list of conflicting inodes to log, again - we had already
logged it before at step 3. After logging it again, we find again
that inode 259 conflicts with him, and we add again 259 to the list,
etc - we end up repeating all the previous steps.
So fix this by skipping logging of conflicting inodes that were already
logged.
Fixes: 6b5fc433a7ad67 ("Btrfs: fix fsync after succession of renames of different files")
CC: stable@vger.kernel.org # 5.1+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
level <0 and level >= BTRFS_MAX_LEVEL are already performed upon
extent buffer read by tree checker in btrfs_check_node.
go. As far as 'level <= 0' we are guaranteed that level is '> 0'
because the value of level _before_ reading 'next' is larger than 1
(otherwise we wouldn't have executed that code at all) this in turn
guarantees that 'level' after btrfs_read_buffer is 'level - 1' since
we verify this invariant in:
btrfs_read_buffer
btree_read_extent_buffer_pages
btrfs_verify_level_key
This guarantees that level can never be '<= 0' so the warn on is
never triggered.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The log_root passed to walk_log_tree is guaranteed to have its
root_key.objectid always be BTRFS_TREE_LOG_OBJECTID. This is by
merit that all log roots of an ordinary root are allocated in
alloc_log_tree which hard-codes objectid to be BTRFS_TREE_LOG_OBJECTID.
In case walk_log_tree is called for a log tree found by btrfs_read_fs_root
in btrfs_recover_log_trees, that function already ensures
found_key.objectid is BTRFS_TREE_LOG_OBJECTID.
No functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
__btrfs_free_reserved_extent now performs the actions of
btrfs_free_and_pin_reserved_extent. But this name is a bit of a
misnomer, since the extent is not really freed but just pinned. Reflect
this in the new name. No semantics changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the NO_HOLES feature, if we punch a hole into a file and then
fsync it, there are cases where a subsequent fsync will miss the fact that
a hole was punched, resulting in the holes not existing after replaying
the log tree.
Essentially these cases all imply that, tree-log.c:copy_items(), is not
invoked for the leafs that delimit holes, because nothing changed those
leafs in the current transaction. And it's precisely copy_items() where
we currenly detect and log holes, which works as long as the holes are
between file extent items in the input leaf or between the beginning of
input leaf and the previous leaf or between the last item in the leaf
and the next leaf.
First example where we miss a hole:
*) The extent items of the inode span multiple leafs;
*) The punched hole covers a range that affects only the extent items of
the first leaf;
*) The fsync operation is done in full mode (BTRFS_INODE_NEEDS_FULL_SYNC
is set in the inode's runtime flags).
That results in the hole not existing after replaying the log tree.
For example, if the fs/subvolume tree has the following layout for a
particular inode:
Leaf N, generation 10:
[ ... INODE_ITEM INODE_REF EXTENT_ITEM (0 64K) EXTENT_ITEM (64K 128K) ]
Leaf N + 1, generation 10:
[ EXTENT_ITEM (128K 64K) ... ]
If at transaction 11 we punch a hole coverting the range [0, 128K[, we end
up dropping the two extent items from leaf N, but we don't touch the other
leaf, so we end up in the following state:
Leaf N, generation 11:
[ ... INODE_ITEM INODE_REF ]
Leaf N + 1, generation 10:
[ EXTENT_ITEM (128K 64K) ... ]
A full fsync after punching the hole will only process leaf N because it
was modified in the current transaction, but not leaf N + 1, since it
was not modified in the current transaction (generation 10 and not 11).
As a result the fsync will not log any holes, because it didn't process
any leaf with extent items.
Second example where we will miss a hole:
*) An inode as its items spanning 5 (or more) leafs;
*) A hole is punched and it covers only the extents items of the 3rd
leaf. This resulsts in deleting the entire leaf and not touching any
of the other leafs.
So the only leaf that is modified in the current transaction, when
punching the hole, is the first leaf, which contains the inode item.
During the full fsync, the only leaf that is passed to copy_items()
is that first leaf, and that's not enough for the hole detection
code in copy_items() to determine there's a hole between the last
file extent item in the 2nd leaf and the first file extent item in
the 3rd leaf (which was the 4th leaf before punching the hole).
Fix this by scanning all leafs and punch holes as necessary when doing a
full fsync (less common than a non-full fsync) when the NO_HOLES feature
is enabled. The lack of explicit file extent items to mark holes makes it
necessary to scan existing extents to determine if holes exist.
A test case for fstests follows soon.
Fixes: 16e7549f045d33 ("Btrfs: incompatible format change to remove hole extents")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
My fsstress modifications coupled with generic/475 uncovered a failure
to mount and replay the log if we hit a orphaned root. We do not want
to replay the log for an orphan root, but it's completely legitimate to
have an orphaned root with a log attached. Fix this by simply skipping
replaying the log. We still need to pin it's root node so that we do
not overwrite it while replaying other logs, as we re-read the log root
at every stage of the replay.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When logging a file that has shared extents (reflinked with other files or
with itself), we can end up logging multiple checksum items that cover
overlapping ranges. This confuses the search for checksums at log replay
time causing some checksums to never be added to the fs/subvolume tree.
Consider the following example of a file that shares the same extent at
offsets 0 and 256Kb:
[ bytenr 13893632, offset 64Kb, len 64Kb ]
0 64Kb
[ bytenr 13631488, offset 64Kb, len 192Kb ]
64Kb 256Kb
[ bytenr 13893632, offset 0, len 256Kb ]
256Kb 512Kb
When logging the inode, at tree-log.c:copy_items(), when processing the
file extent item at offset 0, we log a checksum item covering the range
13959168 to 14024704, which corresponds to 13893632 + 64Kb and 13893632 +
64Kb + 64Kb, respectively.
Later when processing the extent item at offset 256K, we log the checksums
for the range from 13893632 to 14155776 (which corresponds to 13893632 +
256Kb). These checksums get merged with the checksum item for the range
from 13631488 to 13893632 (13631488 + 256Kb), logged by a previous fsync.
So after this we get the two following checksum items in the log tree:
(...)
item 6 key (EXTENT_CSUM EXTENT_CSUM 13631488) itemoff 3095 itemsize 512
range start 13631488 end 14155776 length 524288
item 7 key (EXTENT_CSUM EXTENT_CSUM 13959168) itemoff 3031 itemsize 64
range start 13959168 end 14024704 length 65536
The first one covers the range from the second one, they overlap.
So far this does not cause a problem after replaying the log, because
when replaying the file extent item for offset 256K, we copy all the
checksums for the extent 13893632 from the log tree to the fs/subvolume
tree, since searching for an checksum item for bytenr 13893632 leaves us
at the first checksum item, which covers the whole range of the extent.
However if we write 64Kb to file offset 256Kb for example, we will
not be able to find and copy the checksums for the last 128Kb of the
extent at bytenr 13893632, referenced by the file range 384Kb to 512Kb.
After writing 64Kb into file offset 256Kb we get the following extent
layout for our file:
[ bytenr 13893632, offset 64K, len 64Kb ]
0 64Kb
[ bytenr 13631488, offset 64Kb, len 192Kb ]
64Kb 256Kb
[ bytenr 14155776, offset 0, len 64Kb ]
256Kb 320Kb
[ bytenr 13893632, offset 64Kb, len 192Kb ]
320Kb 512Kb
After fsync'ing the file, if we have a power failure and then mount
the filesystem to replay the log, the following happens:
1) When replaying the file extent item for file offset 320Kb, we
lookup for the checksums for the extent range from 13959168
(13893632 + 64Kb) to 14155776 (13893632 + 256Kb), through a call
to btrfs_lookup_csums_range();
2) btrfs_lookup_csums_range() finds the checksum item that starts
precisely at offset 13959168 (item 7 in the log tree, shown before);
3) However that checksum item only covers 64Kb of data, and not 192Kb
of data;
4) As a result only the checksums for the first 64Kb of data referenced
by the file extent item are found and copied to the fs/subvolume tree.
The remaining 128Kb of data, file range 384Kb to 512Kb, doesn't get
the corresponding data checksums found and copied to the fs/subvolume
tree.
5) After replaying the log userspace will not be able to read the file
range from 384Kb to 512Kb, because the checksums are missing and
resulting in an -EIO error.
The following steps reproduce this scenario:
$ mkfs.btrfs -f /dev/sdc
$ mount /dev/sdc /mnt/sdc
$ xfs_io -f -c "pwrite -S 0xa3 0 256K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
$ xfs_io -c "pwrite -S 0xc7 256K 256K" /mnt/sdc/foobar
$ xfs_io -c "reflink /mnt/sdc/foobar 320K 0 64K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
$ xfs_io -c "pwrite -S 0xe5 256K 64K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
<power failure>
$ mount /dev/sdc /mnt/sdc
$ md5sum /mnt/sdc/foobar
md5sum: /mnt/sdc/foobar: Input/output error
$ dmesg | tail
[165305.003464] BTRFS info (device sdc): no csum found for inode 257 start 401408
[165305.004014] BTRFS info (device sdc): no csum found for inode 257 start 405504
[165305.004559] BTRFS info (device sdc): no csum found for inode 257 start 409600
[165305.005101] BTRFS info (device sdc): no csum found for inode 257 start 413696
[165305.005627] BTRFS info (device sdc): no csum found for inode 257 start 417792
[165305.006134] BTRFS info (device sdc): no csum found for inode 257 start 421888
[165305.006625] BTRFS info (device sdc): no csum found for inode 257 start 425984
[165305.007278] BTRFS info (device sdc): no csum found for inode 257 start 430080
[165305.008248] BTRFS warning (device sdc): csum failed root 5 ino 257 off 393216 csum 0x1337385e expected csum 0x00000000 mirror 1
[165305.009550] BTRFS warning (device sdc): csum failed root 5 ino 257 off 393216 csum 0x1337385e expected csum 0x00000000 mirror 1
Fix this simply by deleting first any checksums, from the log tree, for the
range of the extent we are logging at copy_items(). This ensures we do not
get checksum items in the log tree that have overlapping ranges.
This is a long time issue that has been present since we have the clone
(and deduplication) ioctl, and can happen both when an extent is shared
between different files and within the same file.
A test case for fstests follows soon.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The helper is trivial and we can understand what the atomic_inc on
something named refs does.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The parameter is now always set to NULL and could be dropped. The last
user was get_default_root but that got reworked in 05dbe6837b60 ("Btrfs:
unify subvol= and subvolid= mounting") and the parameter became unused.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
That function adds unnecessary indirection between backref_in_log and
the caller. Furthermore it also "downgrades" backref_in_log's return
value to a boolean, when in fact it could very well be an error.
Rectify the situation by simply opencoding name_in_log_ref in
replay_one_name and properly handling possible return codes from
backref_in_log.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
This function can return a negative error value if btrfs_search_slot
errors for whatever reason or if btrfs_alloc_path runs out of memory.
This is currently problemattic because backref_in_log is treated by its
callers as if it returns boolean.
Fix this by adding proper error handling in callers. That also enables
the function to return the direct error code from btrfs_search_slot.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Direct replacement, though note that the inside of the loop in
btrfs_find_name_in_backref is organized in a slightly different way but
is equvalent.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
-----BEGIN PGP SIGNATURE-----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=zpDj
-----END PGP SIGNATURE-----
Merge tag 'for-5.4-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more stabitly fixes, one build warning fix.
- fix inode allocation under NOFS context
- fix leak in fiemap due to concurrent append writes
- fix log-root tree updates
- fix balance convert of single profile on 32bit architectures
- silence false positive warning on old GCCs (code moved in rc1)"
* tag 'for-5.4-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: silence maybe-uninitialized warning in clone_range
btrfs: fix uninitialized ret in ref-verify
btrfs: allocate new inode in NOFS context
btrfs: fix balance convert to single on 32-bit host CPUs
btrfs: fix incorrect updating of log root tree
Btrfs: fix memory leak due to concurrent append writes with fiemap
We've historically had reports of being unable to mount file systems
because the tree log root couldn't be read. Usually this is the "parent
transid failure", but could be any of the related errors, including
"fsid mismatch" or "bad tree block", depending on which block got
allocated.
The modification of the individual log root items are serialized on the
per-log root root_mutex. This means that any modification to the
per-subvol log root_item is completely protected.
However we update the root item in the log root tree outside of the log
root tree log_mutex. We do this in order to allow multiple subvolumes
to be updated in each log transaction.
This is problematic however because when we are writing the log root
tree out we update the super block with the _current_ log root node
information. Since these two operations happen independently of each
other, you can end up updating the log root tree in between writing out
the dirty blocks and setting the super block to point at the current
root.
This means we'll point at the new root node that hasn't been written
out, instead of the one we should be pointing at. Thus whatever garbage
or old block we end up pointing at complains when we mount the file
system later and try to replay the log.
Fix this by copying the log's root item into a local root item copy.
Then once we're safely under the log_root_tree->log_mutex we update the
root item in the log_root_tree. This way we do not modify the
log_root_tree while we're committing it, fixing the problem.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Chris Mason <clm@fb.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
-----BEGIN PGP SIGNATURE-----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=bY+a
-----END PGP SIGNATURE-----
Merge tag 'for-5.4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"This continues with work on code refactoring, sanity checks and space
handling. There are some less user visible changes, nothing that would
particularly stand out.
User visible changes:
- tree checker, more sanity checks of:
- ROOT_ITEM (key, size, generation, level, alignment, flags)
- EXTENT_ITEM and METADATA_ITEM checks (key, size, offset,
alignment, refs)
- tree block reference items
- EXTENT_DATA_REF (key, hash, offset)
- deprecate flag BTRFS_SUBVOL_CREATE_ASYNC for subvolume creation
ioctl, scheduled removal in 5.7
- delete stale and unused UAPI definitions
BTRFS_DEV_REPLACE_ITEM_STATE_*
- improved export of debugging information available via existing
sysfs directory structure
- try harder to delete relations between qgroups and allow to delete
orphan entries
- remove unreliable space checks before relocation starts
Core:
- space handling:
- improved ticket reservations and other high level logic in
order to remove special cases
- factor flushing infrastructure and use it for different
contexts, allows to remove some special case handling
- reduce metadata reservation when only updating inodes
- reduce global block reserve minimum size (affects small
filesystems)
- improved overcommit logic wrt global block reserve
- tests:
- fix memory leaks in extent IO tree
- catch all TRIM range
Fixes:
- fix ENOSPC errors, leading to transaction aborts, when cloning
extents
- several fixes for inode number cache (mount option inode_cache)
- fix potential soft lockups during send when traversing large trees
- fix unaligned access to space cache pages with SLUB debug on
(PowerPC)
Other:
- refactoring public/private functions, moving to new or more
appropriate files
- defines converted to enums
- error handling improvements
- more assertions and comments
- old code deletion"
* tag 'for-5.4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (138 commits)
btrfs: Relinquish CPUs in btrfs_compare_trees
btrfs: Don't assign retval of btrfs_try_tree_write_lock/btrfs_tree_read_lock_atomic
btrfs: create structure to encode checksum type and length
btrfs: turn checksum type define into an enum
btrfs: add enospc debug messages for ticket failure
btrfs: do not account global reserve in can_overcommit
btrfs: use btrfs_try_granting_tickets in update_global_rsv
btrfs: always reserve our entire size for the global reserve
btrfs: change the minimum global reserve size
btrfs: rename btrfs_space_info_add_old_bytes
btrfs: remove orig_bytes from reserve_ticket
btrfs: fix may_commit_transaction to deal with no partial filling
btrfs: rework wake_all_tickets
btrfs: refactor the ticket wakeup code
btrfs: stop partially refilling tickets when releasing space
btrfs: add space reservation tracepoint for reserved bytes
btrfs: roll tracepoint into btrfs_space_info_update helper
btrfs: do not allow reservations if we have pending tickets
btrfs: stop clearing EXTENT_DIRTY in inode I/O tree
btrfs: treat RWF_{,D}SYNC writes as sync for CRCs
...
Sometimes when fsync'ing a file we need to log that other inodes exist and
when we need to do that we acquire a reference on the inodes and then drop
that reference using iput() after logging them.
That generally is not a problem except if we end up doing the final iput()
(dropping the last reference) on the inode and that inode has a link count
of 0, which can happen in a very short time window if the logging path
gets a reference on the inode while it's being unlinked.
In that case we end up getting the eviction callback, btrfs_evict_inode(),
invoked through the iput() call chain which needs to drop all of the
inode's items from its subvolume btree, and in order to do that, it needs
to join a transaction at the helper function evict_refill_and_join().
However because the task previously started a transaction at the fsync
handler, btrfs_sync_file(), it has current->journal_info already pointing
to a transaction handle and therefore evict_refill_and_join() will get
that transaction handle from btrfs_join_transaction(). From this point on,
two different problems can happen:
1) evict_refill_and_join() will often change the transaction handle's
block reserve (->block_rsv) and set its ->bytes_reserved field to a
value greater than 0. If evict_refill_and_join() never commits the
transaction, the eviction handler ends up decreasing the reference
count (->use_count) of the transaction handle through the call to
btrfs_end_transaction(), and after that point we have a transaction
handle with a NULL ->block_rsv (which is the value prior to the
transaction join from evict_refill_and_join()) and a ->bytes_reserved
value greater than 0. If after the eviction/iput completes the inode
logging path hits an error or it decides that it must fallback to a
transaction commit, the btrfs fsync handle, btrfs_sync_file(), gets a
non-zero value from btrfs_log_dentry_safe(), and because of that
non-zero value it tries to commit the transaction using a handle with
a NULL ->block_rsv and a non-zero ->bytes_reserved value. This makes
the transaction commit hit an assertion failure at
btrfs_trans_release_metadata() because ->bytes_reserved is not zero but
the ->block_rsv is NULL. The produced stack trace for that is like the
following:
[192922.917158] assertion failed: !trans->bytes_reserved, file: fs/btrfs/transaction.c, line: 816
[192922.917553] ------------[ cut here ]------------
[192922.917922] kernel BUG at fs/btrfs/ctree.h:3532!
[192922.918310] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[192922.918666] CPU: 2 PID: 883 Comm: fsstress Tainted: G W 5.1.4-btrfs-next-47 #1
[192922.919035] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
[192922.919801] RIP: 0010:assfail.constprop.25+0x18/0x1a [btrfs]
(...)
[192922.920925] RSP: 0018:ffffaebdc8a27da8 EFLAGS: 00010286
[192922.921315] RAX: 0000000000000051 RBX: ffff95c9c16a41c0 RCX: 0000000000000000
[192922.921692] RDX: 0000000000000000 RSI: ffff95cab6b16838 RDI: ffff95cab6b16838
[192922.922066] RBP: ffff95c9c16a41c0 R08: 0000000000000000 R09: 0000000000000000
[192922.922442] R10: ffffaebdc8a27e70 R11: 0000000000000000 R12: ffff95ca731a0980
[192922.922820] R13: 0000000000000000 R14: ffff95ca84c73338 R15: ffff95ca731a0ea8
[192922.923200] FS: 00007f337eda4e80(0000) GS:ffff95cab6b00000(0000) knlGS:0000000000000000
[192922.923579] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[192922.923948] CR2: 00007f337edad000 CR3: 00000001e00f6002 CR4: 00000000003606e0
[192922.924329] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[192922.924711] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[192922.925105] Call Trace:
[192922.925505] btrfs_trans_release_metadata+0x10c/0x170 [btrfs]
[192922.925911] btrfs_commit_transaction+0x3e/0xaf0 [btrfs]
[192922.926324] btrfs_sync_file+0x44c/0x490 [btrfs]
[192922.926731] do_fsync+0x38/0x60
[192922.927138] __x64_sys_fdatasync+0x13/0x20
[192922.927543] do_syscall_64+0x60/0x1c0
[192922.927939] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[192922.934077] ---[ end trace f00808b12068168f ]---
2) If evict_refill_and_join() decides to commit the transaction, it will
be able to do it, since the nested transaction join only increments the
transaction handle's ->use_count reference counter and it does not
prevent the transaction from getting committed. This means that after
eviction completes, the fsync logging path will be using a transaction
handle that refers to an already committed transaction. What happens
when using such a stale transaction can be unpredictable, we are at
least having a use-after-free on the transaction handle itself, since
the transaction commit will call kmem_cache_free() against the handle
regardless of its ->use_count value, or we can end up silently losing
all the updates to the log tree after that iput() in the logging path,
or using a transaction handle that in the meanwhile was allocated to
another task for a new transaction, etc, pretty much unpredictable
what can happen.
In order to fix both of them, instead of using iput() during logging, use
btrfs_add_delayed_iput(), so that the logging path of fsync never drops
the last reference on an inode, that step is offloaded to a safe context
(usually the cleaner kthread).
The assertion failure issue was sporadically triggered by the test case
generic/475 from fstests, which loads the dm error target while fsstress
is running, which lead to fsync failing while logging inodes with -EIO
errors and then trying later to commit the transaction, triggering the
assertion failure.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Further simplifaction of the get/set helpers is possible when the token
is uniquely tied to an extent buffer. A condition and an assignment can
be avoided.
The initializations are moved closer to the first use when the extent
buffer is valid. There's one exception in __push_leaf_left where the
token is reused.
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik
Filipe Manana
Nikolay Borisov
David Sterba
Qu Wenruo
Linus Torvalds