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fsnotify: fix unlink performance regression

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__fsnotify_parent() has an optimization in place to avoid unneeded
take_dentry_name_snapshot().  When fsnotify_nameremove() was changed
not to call __fsnotify_parent(), we left out the optimization.
Kernel test robot reported a 5% performance regression in concurrent
unlink() workload.

Reported-by: kernel test robot <rong.a.chen@intel.com>
Link: https://lore.kernel.org/lkml/20190505062153.GG29809@shao2-debian/
Link: https://lore.kernel.org/linux-fsdevel/20190104090357.GD22409@quack2.suse.cz/
Fixes: 5f02a87763 ("fsnotify: annotate directory entry modification events")
CC: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein
2019-05-05 12:15:49 +03:00
committed by Jan Kara
parent 11a6f8e2db
commit 4d8e7055a4
3 changed files with 45 additions and 33 deletions
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41
fs/notify/fsnotify.c
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@@ -107,6 +107,47 @@ void fsnotify_sb_delete(struct super_block *sb)
fsnotify_clear_marks_by_sb(sb);
}
/*
* fsnotify_nameremove - a filename was removed from a directory
*
* This is mostly called under parent vfs inode lock so name and
* dentry->d_parent should be stable. However there are some corner cases where
* inode lock is not held. So to be on the safe side and be reselient to future
* callers and out of tree users of d_delete(), we do not assume that d_parent
* and d_name are stable and we use dget_parent() and
* take_dentry_name_snapshot() to grab stable references.
*/
void fsnotify_nameremove(struct dentry *dentry, int isdir)
{
struct dentry *parent;
struct name_snapshot name;
__u32 mask = FS_DELETE;
/* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */
if (IS_ROOT(dentry))
return;
if (isdir)
mask |= FS_ISDIR;
parent = dget_parent(dentry);
/* Avoid unneeded take_dentry_name_snapshot() */
if (!(d_inode(parent)->i_fsnotify_mask & FS_DELETE) &&
!(dentry->d_sb->s_fsnotify_mask & FS_DELETE))
goto out_dput;
take_dentry_name_snapshot(&name, dentry);
fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
name.name, 0);
release_dentry_name_snapshot(&name);
out_dput:
dput(parent);
}
EXPORT_SYMBOL(fsnotify_nameremove);
/*
* Given an inode, first check if we care what happens to our children. Inotify
* and dnotify both tell their parents about events. If we care about any event