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nfs: per-name sillyunlink exclusion

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use d_alloc_parallel() for sillyunlink/lookup exclusion and
explicit rwsem (nfs_rmdir() being a writer and nfs_call_unlink() -
a reader) for rmdir/sillyunlink one.

That ought to make lookup/readdir/!O_CREAT atomic_open really
parallel on NFS.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-04-28 23:56:31 -04:00
parent 9ac3d3e846
commit 884be17535
7 changed files with 71 additions and 174 deletions
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9
fs/nfs/dir.c
View File

@ -909,7 +909,6 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
desc->decode = NFS_PROTO(inode)->decode_dirent;
desc->plus = nfs_use_readdirplus(inode, ctx) ? 1 : 0;
nfs_block_sillyrename(dentry);
if (ctx->pos == 0 || nfs_dir_mapping_need_revalidate(inode))
res = nfs_revalidate_mapping(inode, file->f_mapping);
if (res < 0)
@ -945,7 +944,6 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
break;
} while (!desc->eof);
out:
nfs_unblock_sillyrename(dentry);
if (res > 0)
res = 0;
dfprintk(FILE, "NFS: readdir(%pD2) returns %d\n", file, res);
@ -1398,7 +1396,6 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in
parent = dentry->d_parent;
/* Protect against concurrent sillydeletes */
trace_nfs_lookup_enter(dir, dentry, flags);
nfs_block_sillyrename(parent);
error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
if (error == -ENOENT)
goto no_entry;
@ -1423,7 +1420,6 @@ no_entry:
}
nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
out_unblock_sillyrename:
nfs_unblock_sillyrename(parent);
trace_nfs_lookup_exit(dir, dentry, flags, error);
nfs4_label_free(label);
out:
@ -1535,9 +1531,7 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
goto out;
trace_nfs_atomic_open_enter(dir, ctx, open_flags);
nfs_block_sillyrename(dentry->d_parent);
inode = NFS_PROTO(dir)->open_context(dir, ctx, open_flags, &attr, opened);
nfs_unblock_sillyrename(dentry->d_parent);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
@ -1781,7 +1775,7 @@ int nfs_rmdir(struct inode *dir, struct dentry *dentry)
trace_nfs_rmdir_enter(dir, dentry);
if (d_really_is_positive(dentry)) {
nfs_wait_on_sillyrename(dentry);
down_write(&NFS_I(d_inode(dentry))->rmdir_sem);
error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
/* Ensure the VFS deletes this inode */
switch (error) {
@ -1791,6 +1785,7 @@ int nfs_rmdir(struct inode *dir, struct dentry *dentry)
case -ENOENT:
nfs_dentry_handle_enoent(dentry);
}
up_write(&NFS_I(d_inode(dentry))->rmdir_sem);
} else
error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
trace_nfs_rmdir_exit(dir, dentry, error);

4
fs/nfs/inode.c
View File

@ -1958,9 +1958,7 @@ static void init_once(void *foo)
nfsi->nrequests = 0;
nfsi->commit_info.ncommit = 0;
atomic_set(&nfsi->commit_info.rpcs_out, 0);
atomic_set(&nfsi->silly_count, 1);
INIT_HLIST_HEAD(&nfsi->silly_list);
init_waitqueue_head(&nfsi->waitqueue);
init_rwsem(&nfsi->rmdir_sem);
nfs4_init_once(nfsi);
}

2
fs/nfs/nfs4proc.c
View File

@ -3777,7 +3777,7 @@ static void nfs4_proc_unlink_setup(struct rpc_message *msg, struct inode *dir)
static void nfs4_proc_unlink_rpc_prepare(struct rpc_task *task, struct nfs_unlinkdata *data)
{
nfs4_setup_sequence(NFS_SERVER(data->dir),
nfs4_setup_sequence(NFS_SB(data->dentry->d_sb),
&data->args.seq_args,
&data->res.seq_res,
task);

2
fs/nfs/nfstrace.h
View File

@ -702,7 +702,7 @@ TRACE_EVENT(nfs_sillyrename_unlink,
),
TP_fast_assign(
struct inode *dir = data->dir;
struct inode *dir = d_inode(data->dentry->d_parent);
size_t len = data->args.name.len;
__entry->dev = dir->i_sb->s_dev;
__entry->dir = NFS_FILEID(dir);

205
fs/nfs/unlink.c
View File

@ -30,45 +30,11 @@
static void
nfs_free_unlinkdata(struct nfs_unlinkdata *data)
{
iput(data->dir);
put_rpccred(data->cred);
kfree(data->args.name.name);
kfree(data);
}
#define NAME_ALLOC_LEN(len) ((len+16) & ~15)
/**
* nfs_copy_dname - copy dentry name to data structure
* @dentry: pointer to dentry
* @data: nfs_unlinkdata
*/
static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
{
char *str;
int len = dentry->d_name.len;
str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
if (!str)
return -ENOMEM;
data->args.name.len = len;
data->args.name.name = str;
return 0;
}
static void nfs_free_dname(struct nfs_unlinkdata *data)
{
kfree(data->args.name.name);
data->args.name.name = NULL;
data->args.name.len = 0;
}
static void nfs_dec_sillycount(struct inode *dir)
{
struct nfs_inode *nfsi = NFS_I(dir);
if (atomic_dec_return(&nfsi->silly_count) == 1)
wake_up(&nfsi->waitqueue);
}
/**
* nfs_async_unlink_done - Sillydelete post-processing
* @task: rpc_task of the sillydelete
@ -78,7 +44,7 @@ static void nfs_dec_sillycount(struct inode *dir)
static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
{
struct nfs_unlinkdata *data = calldata;
struct inode *dir = data->dir;
struct inode *dir = d_inode(data->dentry->d_parent);
trace_nfs_sillyrename_unlink(data, task->tk_status);
if (!NFS_PROTO(dir)->unlink_done(task, dir))
@ -95,17 +61,21 @@ static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
static void nfs_async_unlink_release(void *calldata)
{
struct nfs_unlinkdata *data = calldata;
struct super_block *sb = data->dir->i_sb;
struct dentry *dentry = data->dentry;
struct super_block *sb = dentry->d_sb;
nfs_dec_sillycount(data->dir);
up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
d_lookup_done(dentry);
nfs_free_unlinkdata(data);
dput(dentry);
nfs_sb_deactive(sb);
}
static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
{
struct nfs_unlinkdata *data = calldata;
NFS_PROTO(data->dir)->unlink_rpc_prepare(task, data);
struct inode *dir = d_inode(data->dentry->d_parent);
NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
}
static const struct rpc_call_ops nfs_unlink_ops = {
@ -114,7 +84,7 @@ static const struct rpc_call_ops nfs_unlink_ops = {
.rpc_call_prepare = nfs_unlink_prepare,
};
static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
static void nfs_do_call_unlink(struct nfs_unlinkdata *data)
{
struct rpc_message msg = {
.rpc_argp = &data->args,
@ -129,44 +99,7 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
.flags = RPC_TASK_ASYNC,
};
struct rpc_task *task;
struct dentry *alias;
alias = d_lookup(parent, &data->args.name);
if (alias != NULL) {
int ret;
void *devname_garbage = NULL;
/*
* Hey, we raced with lookup... See if we need to transfer
* the sillyrename information to the aliased dentry.
*/
nfs_free_dname(data);
ret = nfs_copy_dname(alias, data);
spin_lock(&alias->d_lock);
if (ret == 0 && d_really_is_positive(alias) &&
!(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
devname_garbage = alias->d_fsdata;
alias->d_fsdata = data;
alias->d_flags |= DCACHE_NFSFS_RENAMED;
ret = 1;
} else
ret = 0;
spin_unlock(&alias->d_lock);
nfs_dec_sillycount(dir);
dput(alias);
/*
* If we'd displaced old cached devname, free it. At that
* point dentry is definitely not a root, so we won't need
* that anymore.
*/
kfree(devname_garbage);
return ret;
}
data->dir = igrab(dir);
if (!data->dir) {
nfs_dec_sillycount(dir);
return 0;
}
struct inode *dir = d_inode(data->dentry->d_parent);
nfs_sb_active(dir->i_sb);
data->args.fh = NFS_FH(dir);
nfs_fattr_init(data->res.dir_attr);
@ -177,71 +110,50 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
task = rpc_run_task(&task_setup_data);
if (!IS_ERR(task))
rpc_put_task_async(task);
return 1;
}
static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
{
struct dentry *parent;
struct inode *dir;
int ret = 0;
struct inode *dir = d_inode(dentry->d_parent);
struct dentry *alias;
down_read_non_owner(&NFS_I(dir)->rmdir_sem);
alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
if (IS_ERR(alias)) {
up_read_non_owner(&NFS_I(dir)->rmdir_sem);
return 0;
}
if (!d_in_lookup(alias)) {
int ret;
void *devname_garbage = NULL;
parent = dget_parent(dentry);
if (parent == NULL)
goto out_free;
dir = d_inode(parent);
/* Non-exclusive lock protects against concurrent lookup() calls */
spin_lock(&dir->i_lock);
if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
/* Deferred delete */
hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
spin_unlock(&dir->i_lock);
/*
* Hey, we raced with lookup... See if we need to transfer
* the sillyrename information to the aliased dentry.
*/
spin_lock(&alias->d_lock);
if (d_really_is_positive(alias) &&
!(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
devname_garbage = alias->d_fsdata;
alias->d_fsdata = data;
alias->d_flags |= DCACHE_NFSFS_RENAMED;
ret = 1;
goto out_dput;
}
spin_unlock(&dir->i_lock);
ret = nfs_do_call_unlink(parent, dir, data);
out_dput:
dput(parent);
out_free:
} else
ret = 0;
spin_unlock(&alias->d_lock);
dput(alias);
up_read_non_owner(&NFS_I(dir)->rmdir_sem);
/*
* If we'd displaced old cached devname, free it. At that
* point dentry is definitely not a root, so we won't need
* that anymore.
*/
kfree(devname_garbage);
return ret;
}
void nfs_wait_on_sillyrename(struct dentry *dentry)
{
struct nfs_inode *nfsi = NFS_I(d_inode(dentry));
wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) <= 1);
}
void nfs_block_sillyrename(struct dentry *dentry)
{
struct nfs_inode *nfsi = NFS_I(d_inode(dentry));
wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
}
void nfs_unblock_sillyrename(struct dentry *dentry)
{
struct inode *dir = d_inode(dentry);
struct nfs_inode *nfsi = NFS_I(dir);
struct nfs_unlinkdata *data;
atomic_inc(&nfsi->silly_count);
wake_up(&nfsi->waitqueue);
spin_lock(&dir->i_lock);
while (!hlist_empty(&nfsi->silly_list)) {
if (!atomic_inc_not_zero(&nfsi->silly_count))
break;
data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
hlist_del(&data->list);
spin_unlock(&dir->i_lock);
if (nfs_do_call_unlink(dentry, dir, data) == 0)
nfs_free_unlinkdata(data);
spin_lock(&dir->i_lock);
}
spin_unlock(&dir->i_lock);
data->dentry = alias;
nfs_do_call_unlink(data);
return 1;
}
/**
@ -250,7 +162,7 @@ void nfs_unblock_sillyrename(struct dentry *dentry)
* @dentry: dentry to unlink
*/
static int
nfs_async_unlink(struct inode *dir, struct dentry *dentry)
nfs_async_unlink(struct dentry *dentry, struct qstr *name)
{
struct nfs_unlinkdata *data;
int status = -ENOMEM;
@ -259,13 +171,18 @@ nfs_async_unlink(struct inode *dir, struct dentry *dentry)
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (data == NULL)
goto out;
data->args.name.name = kstrdup(name->name, GFP_KERNEL);
if (!data->args.name.name)
goto out_free;
data->args.name.len = name->len;
data->cred = rpc_lookup_cred();
if (IS_ERR(data->cred)) {
status = PTR_ERR(data->cred);
goto out_free;
goto out_free_name;
}
data->res.dir_attr = &data->dir_attr;
init_waitqueue_head(&data->wq);
status = -EBUSY;
spin_lock(&dentry->d_lock);
@ -285,6 +202,8 @@ nfs_async_unlink(struct inode *dir, struct dentry *dentry)
out_unlock:
spin_unlock(&dentry->d_lock);
put_rpccred(data->cred);
out_free_name:
kfree(data->args.name.name);
out_free:
kfree(data);
out:
@ -303,17 +222,15 @@ out:
void
nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
{
struct nfs_unlinkdata *data = NULL;
struct nfs_unlinkdata *data;
spin_lock(&dentry->d_lock);
if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
data = dentry->d_fsdata;
dentry->d_fsdata = NULL;
}
spin_unlock(&dentry->d_lock);
if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
if (NFS_STALE(inode) || !nfs_call_unlink(dentry, data))
nfs_free_unlinkdata(data);
}
@ -560,18 +477,10 @@ nfs_sillyrename(struct inode *dir, struct dentry *dentry)
/* queue unlink first. Can't do this from rpc_release as it
* has to allocate memory
*/
error = nfs_async_unlink(dir, dentry);
error = nfs_async_unlink(dentry, &sdentry->d_name);
if (error)
goto out_dput;
/* populate unlinkdata with the right dname */
error = nfs_copy_dname(sdentry,
(struct nfs_unlinkdata *)dentry->d_fsdata);
if (error) {
nfs_cancel_async_unlink(dentry);
goto out_dput;
}
/* run the rename task, undo unlink if it fails */
task = nfs_async_rename(dir, dir, dentry, sdentry,
nfs_complete_sillyrename);

11
include/linux/nfs_fs.h
View File

@ -163,11 +163,9 @@ struct nfs_inode {
/* Open contexts for shared mmap writes */
struct list_head open_files;
/* Number of in-flight sillydelete RPC calls */
atomic_t silly_count;
/* List of deferred sillydelete requests */
struct hlist_head silly_list;
wait_queue_head_t waitqueue;
/* Readers: in-flight sillydelete RPC calls */
/* Writers: rmdir */
struct rw_semaphore rmdir_sem;
#if IS_ENABLED(CONFIG_NFS_V4)
struct nfs4_cached_acl *nfs4_acl;
@ -492,9 +490,6 @@ extern void nfs_release_automount_timer(void);
* linux/fs/nfs/unlink.c
*/
extern void nfs_complete_unlink(struct dentry *dentry, struct inode *);
extern void nfs_wait_on_sillyrename(struct dentry *dentry);
extern void nfs_block_sillyrename(struct dentry *dentry);
extern void nfs_unblock_sillyrename(struct dentry *dentry);
/*
* linux/fs/nfs/write.c

4
include/linux/nfs_xdr.h
View File

@ -1468,10 +1468,10 @@ struct nfs_pgio_completion_ops {
};
struct nfs_unlinkdata {
struct hlist_node list;
struct nfs_removeargs args;
struct nfs_removeres res;
struct inode *dir;
struct dentry *dentry;
wait_queue_head_t wq;
struct rpc_cred *cred;
struct nfs_fattr dir_attr;
long timeout;