diff options
| author | Jan Kara <jack@suse.cz> | 2016-05-19 17:08:59 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-19 19:12:14 -0700 |
| commit | 35e481761cdc688dbee0ef552a13f49af8eba6cc (patch) | |
| tree | f04cadb49418e42a70d4d4b14ebabfb0ca48df8e /include/linux/fsnotify_backend.h | |
| parent | 2600a46ee0ed57c0e0a382c2a37ebac64d374d20 (diff) | |
| download | linux-35e481761cdc688dbee0ef552a13f49af8eba6cc.tar.gz | |
fsnotify: avoid spurious EMFILE errors from inotify_init()
Inotify instance is destroyed when all references to it are dropped.
That not only means that the corresponding file descriptor needs to be
closed but also that all corresponding instance marks are freed (as each
mark holds a reference to the inotify instance). However marks are
freed only after SRCU period ends which can take some time and thus if
user rapidly creates and frees inotify instances, number of existing
inotify instances can exceed max_user_instances limit although from user
point of view there is always at most one existing instance. Thus
inotify_init() returns EMFILE error which is hard to justify from user
point of view. This problem is exposed by LTP inotify06 testcase on
some machines.
We fix the problem by making sure all group marks are properly freed
while destroying inotify instance. We wait for SRCU period to end in
that path anyway since we have to make sure there is no event being
added to the instance while we are tearing down the instance. So it
takes only some plumbing to allow for marks to be destroyed in that path
as well and not from a dedicated work item.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Tested-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/fsnotify_backend.h')
| -rw-r--r-- | include/linux/fsnotify_backend.h | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index 1259e53d9296..29f917517299 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -359,8 +359,6 @@ extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group) extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); -/* run all the marks in a group, and flag them to be freed */ -extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); extern void fsnotify_get_mark(struct fsnotify_mark *mark); extern void fsnotify_put_mark(struct fsnotify_mark *mark); extern void fsnotify_unmount_inodes(struct super_block *sb); |