linux/fs/xfs/libxfs/xfs_trans_inode.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_inode_item.h"
#include <linux/iversion.h>
/*
* Add a locked inode to the transaction.
*
* The inode must be locked, and it cannot be associated with any transaction.
* If lock_flags is non-zero the inode will be unlocked on transaction commit.
*/
void
xfs_trans_ijoin(
struct xfs_trans *tp,
struct xfs_inode *ip,
uint lock_flags)
{
struct xfs_inode_log_item *iip;
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
if (ip->i_itemp == NULL)
xfs_inode_item_init(ip, ip->i_mount);
iip = ip->i_itemp;
ASSERT(iip->ili_lock_flags == 0);
iip->ili_lock_flags = lock_flags;
xfs: Don't allow logging of XFS_ISTALE inodes In tracking down a problem in this patchset, I discovered we are reclaiming dirty stale inodes. This wasn't discovered until inodes were always attached to the cluster buffer and then the rcu callback that freed inodes was assert failing because the inode still had an active pointer to the cluster buffer after it had been reclaimed. Debugging the issue indicated that this was a pre-existing issue resulting from the way the inodes are handled in xfs_inactive_ifree. When we free a cluster buffer from xfs_ifree_cluster, all the inodes in cache are marked XFS_ISTALE. Those that are clean have nothing else done to them and so eventually get cleaned up by background reclaim. i.e. it is assumed we'll never dirty/relog an inode marked XFS_ISTALE. On journal commit dirty stale inodes as are handled by both buffer and inode log items to run though xfs_istale_done() and removed from the AIL (buffer log item commit) or the log item will simply unpin it because the buffer log item will clean it. What happens to any specific inode is entirely dependent on which log item wins the commit race, but the result is the same - stale inodes are clean, not attached to the cluster buffer, and not in the AIL. Hence inode reclaim can just free these inodes without further care. However, if the stale inode is relogged, it gets dirtied again and relogged into the CIL. Most of the time this isn't an issue, because relogging simply changes the inode's location in the current checkpoint. Problems arise, however, when the CIL checkpoints between two transactions in the xfs_inactive_ifree() deferops processing. This results in the XFS_ISTALE inode being redirtied and inserted into the CIL without any of the other stale cluster buffer infrastructure being in place. Hence on journal commit, it simply gets unpinned, so it remains dirty in memory. Everything in inode writeback avoids XFS_ISTALE inodes so it can't be written back, and it is not tracked in the AIL so there's not even a trigger to attempt to clean the inode. Hence the inode just sits dirty in memory until inode reclaim comes along, sees that it is XFS_ISTALE, and goes to reclaim it. This reclaiming of a dirty inode caused use after free, list corruptions and other nasty issues later in this patchset. Hence this patch addresses a violation of the "never log XFS_ISTALE inodes" caused by the deferops processing rolling a transaction and relogging a stale inode in xfs_inactive_free. It also adds a bunch of asserts to catch this problem in debug kernels so that we don't reintroduce this problem in future. Reproducer for this issue was generic/558 on a v4 filesystem. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:45 +03:00
ASSERT(!xfs_iflags_test(ip, XFS_ISTALE));
/*
* Get a log_item_desc to point at the new item.
*/
xfs_trans_add_item(tp, &iip->ili_item);
}
/*
* Transactional inode timestamp update. Requires the inode to be locked and
* joined to the transaction supplied. Relies on the transaction subsystem to
* track dirty state and update/writeback the inode accordingly.
*/
void
xfs_trans_ichgtime(
struct xfs_trans *tp,
struct xfs_inode *ip,
int flags)
{
struct inode *inode = VFS_I(ip);
struct timespec64 tv;
ASSERT(tp);
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
tv = current_time(inode);
if (flags & XFS_ICHGTIME_MOD)
inode->i_mtime = tv;
if (flags & XFS_ICHGTIME_CHG)
inode->i_ctime = tv;
if (flags & XFS_ICHGTIME_CREATE)
ip->i_crtime = tv;
}
/*
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
* This is called to mark the fields indicated in fieldmask as needing to be
* logged when the transaction is committed. The inode must already be
* associated with the given transaction.
*
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
* The values for fieldmask are defined in xfs_inode_item.h. We always log all
* of the core inode if any of it has changed, and we always log all of the
* inline data/extents/b-tree root if any of them has changed.
*
* Grab and pin the cluster buffer associated with this inode to avoid RMW
* cycles at inode writeback time. Avoid the need to add error handling to every
* xfs_trans_log_inode() call by shutting down on read error. This will cause
* transactions to fail and everything to error out, just like if we return a
* read error in a dirty transaction and cancel it.
*/
void
xfs_trans_log_inode(
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
struct xfs_trans *tp,
struct xfs_inode *ip,
uint flags)
{
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
struct xfs_inode_log_item *iip = ip->i_itemp;
struct inode *inode = VFS_I(ip);
uint iversion_flags = 0;
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
ASSERT(iip);
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
xfs: Don't allow logging of XFS_ISTALE inodes In tracking down a problem in this patchset, I discovered we are reclaiming dirty stale inodes. This wasn't discovered until inodes were always attached to the cluster buffer and then the rcu callback that freed inodes was assert failing because the inode still had an active pointer to the cluster buffer after it had been reclaimed. Debugging the issue indicated that this was a pre-existing issue resulting from the way the inodes are handled in xfs_inactive_ifree. When we free a cluster buffer from xfs_ifree_cluster, all the inodes in cache are marked XFS_ISTALE. Those that are clean have nothing else done to them and so eventually get cleaned up by background reclaim. i.e. it is assumed we'll never dirty/relog an inode marked XFS_ISTALE. On journal commit dirty stale inodes as are handled by both buffer and inode log items to run though xfs_istale_done() and removed from the AIL (buffer log item commit) or the log item will simply unpin it because the buffer log item will clean it. What happens to any specific inode is entirely dependent on which log item wins the commit race, but the result is the same - stale inodes are clean, not attached to the cluster buffer, and not in the AIL. Hence inode reclaim can just free these inodes without further care. However, if the stale inode is relogged, it gets dirtied again and relogged into the CIL. Most of the time this isn't an issue, because relogging simply changes the inode's location in the current checkpoint. Problems arise, however, when the CIL checkpoints between two transactions in the xfs_inactive_ifree() deferops processing. This results in the XFS_ISTALE inode being redirtied and inserted into the CIL without any of the other stale cluster buffer infrastructure being in place. Hence on journal commit, it simply gets unpinned, so it remains dirty in memory. Everything in inode writeback avoids XFS_ISTALE inodes so it can't be written back, and it is not tracked in the AIL so there's not even a trigger to attempt to clean the inode. Hence the inode just sits dirty in memory until inode reclaim comes along, sees that it is XFS_ISTALE, and goes to reclaim it. This reclaiming of a dirty inode caused use after free, list corruptions and other nasty issues later in this patchset. Hence this patch addresses a violation of the "never log XFS_ISTALE inodes" caused by the deferops processing rolling a transaction and relogging a stale inode in xfs_inactive_free. It also adds a bunch of asserts to catch this problem in debug kernels so that we don't reintroduce this problem in future. Reproducer for this issue was generic/558 on a v4 filesystem. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:45 +03:00
ASSERT(!xfs_iflags_test(ip, XFS_ISTALE));
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
tp->t_flags |= XFS_TRANS_DIRTY;
/*
* Don't bother with i_lock for the I_DIRTY_TIME check here, as races
* don't matter - we either will need an extra transaction in 24 hours
* to log the timestamps, or will clear already cleared fields in the
* worst case.
*/
if (inode->i_state & I_DIRTY_TIME) {
spin_lock(&inode->i_lock);
inode->i_state &= ~I_DIRTY_TIME;
spin_unlock(&inode->i_lock);
}
/*
* First time we log the inode in a transaction, bump the inode change
* counter if it is configured for this to occur. While we have the
* inode locked exclusively for metadata modification, we can usually
* avoid setting XFS_ILOG_CORE if no one has queried the value since
* the last time it was incremented. If we have XFS_ILOG_CORE already
* set however, then go ahead and bump the i_version counter
* unconditionally.
*/
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
if (!test_and_set_bit(XFS_LI_DIRTY, &iip->ili_item.li_flags)) {
if (IS_I_VERSION(inode) &&
inode_maybe_inc_iversion(inode, flags & XFS_ILOG_CORE))
iversion_flags = XFS_ILOG_CORE;
}
/*
* If we're updating the inode core or the timestamps and it's possible
* to upgrade this inode to bigtime format, do so now.
*/
if ((flags & (XFS_ILOG_CORE | XFS_ILOG_TIMESTAMP)) &&
xfs_has_bigtime(ip->i_mount) &&
!xfs_inode_has_bigtime(ip)) {
ip->i_diflags2 |= XFS_DIFLAG2_BIGTIME;
flags |= XFS_ILOG_CORE;
}
xfs: validate extsz hints against rt extent size when rtinherit is set The RTINHERIT bit can be set on a directory so that newly created regular files will have the REALTIME bit set to store their data on the realtime volume. If an extent size hint (and EXTSZINHERIT) are set on the directory, the hint will also be copied into the new file. As pointed out in previous patches, for realtime files we require the extent size hint be an integer multiple of the realtime extent, but we don't perform the same validation on a directory with both RTINHERIT and EXTSZINHERIT set, even though the only use-case of that combination is to propagate extent size hints into new realtime files. This leads to inode corruption errors when the bad values are propagated. Because there may be existing filesystems with such a configuration, we cannot simply amend the inode verifier to trip on these directories and call it a day because that will cause previously "working" filesystems to start throwing errors abruptly. Note that it's valid to have directories with rtinherit set even if there is no realtime volume, in which case the problem does not manifest because rtinherit is ignored if there's no realtime device; and it's possible that someone set the flag, crashed, repaired the filesystem (which clears the hint on the realtime file) and continued. Therefore, mitigate this issue in several ways: First, if we try to write out an inode with both rtinherit/extszinherit set and an unaligned extent size hint, turn off the hint to correct the error. Second, if someone tries to misconfigure a directory via the fssetxattr ioctl, fail the ioctl. Third, reverify both extent size hint values when we propagate heritable inode attributes from parent to child, to prevent misconfigurations from spreading. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com>
2021-05-12 22:51:26 +03:00
/*
* Inode verifiers do not check that the extent size hint is an integer
* multiple of the rt extent size on a directory with both rtinherit
* and extszinherit flags set. If we're logging a directory that is
* misconfigured in this way, clear the hint.
xfs: validate extsz hints against rt extent size when rtinherit is set The RTINHERIT bit can be set on a directory so that newly created regular files will have the REALTIME bit set to store their data on the realtime volume. If an extent size hint (and EXTSZINHERIT) are set on the directory, the hint will also be copied into the new file. As pointed out in previous patches, for realtime files we require the extent size hint be an integer multiple of the realtime extent, but we don't perform the same validation on a directory with both RTINHERIT and EXTSZINHERIT set, even though the only use-case of that combination is to propagate extent size hints into new realtime files. This leads to inode corruption errors when the bad values are propagated. Because there may be existing filesystems with such a configuration, we cannot simply amend the inode verifier to trip on these directories and call it a day because that will cause previously "working" filesystems to start throwing errors abruptly. Note that it's valid to have directories with rtinherit set even if there is no realtime volume, in which case the problem does not manifest because rtinherit is ignored if there's no realtime device; and it's possible that someone set the flag, crashed, repaired the filesystem (which clears the hint on the realtime file) and continued. Therefore, mitigate this issue in several ways: First, if we try to write out an inode with both rtinherit/extszinherit set and an unaligned extent size hint, turn off the hint to correct the error. Second, if someone tries to misconfigure a directory via the fssetxattr ioctl, fail the ioctl. Third, reverify both extent size hint values when we propagate heritable inode attributes from parent to child, to prevent misconfigurations from spreading. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com>
2021-05-12 22:51:26 +03:00
*/
if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
(ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) &&
(ip->i_extsize % ip->i_mount->m_sb.sb_rextsize) > 0) {
ip->i_diflags &= ~(XFS_DIFLAG_EXTSIZE |
XFS_DIFLAG_EXTSZINHERIT);
ip->i_extsize = 0;
flags |= XFS_ILOG_CORE;
}
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
/*
* Record the specific change for fdatasync optimisation. This allows
* fdatasync to skip log forces for inodes that are only timestamp
* dirty.
*/
spin_lock(&iip->ili_lock);
iip->ili_fsync_fields |= flags;
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
if (!iip->ili_item.li_buf) {
struct xfs_buf *bp;
int error;
/*
* We hold the ILOCK here, so this inode is not going to be
* flushed while we are here. Further, because there is no
* buffer attached to the item, we know that there is no IO in
* progress, so nothing will clear the ili_fields while we read
* in the buffer. Hence we can safely drop the spin lock and
* read the buffer knowing that the state will not change from
* here.
*/
spin_unlock(&iip->ili_lock);
error = xfs_imap_to_bp(ip->i_mount, tp, &ip->i_imap, &bp);
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
if (error) {
xfs_force_shutdown(ip->i_mount, SHUTDOWN_META_IO_ERROR);
return;
}
/*
* We need an explicit buffer reference for the log item but
* don't want the buffer to remain attached to the transaction.
* Hold the buffer but release the transaction reference once
* we've attached the inode log item to the buffer log item
* list.
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
*/
xfs_buf_hold(bp);
spin_lock(&iip->ili_lock);
iip->ili_item.li_buf = bp;
bp->b_flags |= _XBF_INODES;
list_add_tail(&iip->ili_item.li_bio_list, &bp->b_li_list);
xfs_trans_brelse(tp, bp);
xfs: pin inode backing buffer to the inode log item When we dirty an inode, we are going to have to write it disk at some point in the near future. This requires the inode cluster backing buffer to be present in memory. Unfortunately, under severe memory pressure we can reclaim the inode backing buffer while the inode is dirty in memory, resulting in stalling the AIL pushing because it has to do a read-modify-write cycle on the cluster buffer. When we have no memory available, the read of the cluster buffer blocks the AIL pushing process, and this causes all sorts of issues for memory reclaim as it requires inode writeback to make forwards progress. Allocating a cluster buffer causes more memory pressure, and results in more cluster buffers to be reclaimed, resulting in more RMW cycles to be done in the AIL context and everything then backs up on AIL progress. Only the synchronous inode cluster writeback in the the inode reclaim code provides some level of forwards progress guarantees that prevent OOM-killer rampages in this situation. Fix this by pinning the inode backing buffer to the inode log item when the inode is first dirtied (i.e. in xfs_trans_log_inode()). This may mean the first modification of an inode that has been held in cache for a long time may block on a cluster buffer read, but we can do that in transaction context and block safely until the buffer has been allocated and read. Once we have the cluster buffer, the inode log item takes a reference to it, pinning it in memory, and attaches it to the log item for future reference. This means we can always grab the cluster buffer from the inode log item when we need it. When the inode is finally cleaned and removed from the AIL, we can drop the reference the inode log item holds on the cluster buffer. Once all inodes on the cluster buffer are clean, the cluster buffer will be unpinned and it will be available for memory reclaim to reclaim again. This avoids the issues with needing to do RMW cycles in the AIL pushing context, and hence allows complete non-blocking inode flushing to be performed by the AIL pushing context. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:49:15 +03:00
}
/*
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
* Always OR in the bits from the ili_last_fields field. This is to
* coordinate with the xfs_iflush() and xfs_buf_inode_iodone() routines
* in the eventual clearing of the ili_fields bits. See the big comment
* in xfs_iflush() for an explanation of this coordination mechanism.
*/
xfs: add an inode item lock The inode log item is kind of special in that it can be aggregating new changes in memory at the same time time existing changes are being written back to disk. This means there are fields in the log item that are accessed concurrently from contexts that don't share any locking at all. e.g. updating ili_last_fields occurs at flush time under the ILOCK_EXCL and flush lock at flush time, under the flush lock at IO completion time, and is read under the ILOCK_EXCL when the inode is logged. Hence there is no actual serialisation between reading the field during logging of the inode in transactions vs clearing the field in IO completion. We currently get away with this by the fact that we are only clearing fields in IO completion, and nothing bad happens if we accidentally log more of the inode than we actually modify. Worst case is we consume a tiny bit more memory and log bandwidth. However, if we want to do more complex state manipulations on the log item that requires updates at all three of these potential locations, we need to have some mechanism of serialising those operations. To do this, introduce a spinlock into the log item to serialise internal state. This could be done via the xfs_inode i_flags_lock, but this then leads to potential lock inversion issues where inode flag updates need to occur inside locks that best nest inside the inode log item locks (e.g. marking inodes stale during inode cluster freeing). Using a separate spinlock avoids these sorts of problems and simplifies future code. This does not touch the use of ili_fields in the item formatting code - that is entirely protected by the ILOCK_EXCL at this point in time, so it remains untouched. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-06-30 00:48:46 +03:00
iip->ili_fields |= (flags | iip->ili_last_fields | iversion_flags);
spin_unlock(&iip->ili_lock);
}
int
xfs_trans_roll_inode(
struct xfs_trans **tpp,
struct xfs_inode *ip)
{
int error;
xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
error = xfs_trans_roll(tpp);
if (!error)
xfs_trans_ijoin(*tpp, ip, 0);
return error;
}