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inotify: Do not drop mark reference under idr_lock 

Dropping mark reference can result in mark being freed. Although it
should not happen in inotify_remove_from_idr() since caller should hold
another reference, just don't risk lock up just after WARN_ON
unnecessarily. Also fold do_inotify_remove_from_idr() into the single
callsite as that function really is just two lines of real code.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2016-12-21 11:50:39 +01:00
parent 08991e83b7
commit e725376058
1 changed files with 6 additions and 18 deletions
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24
fs/notify/inotify/inotify_user.c
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@ -395,21 +395,6 @@ static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
return i_mark;
}
static void do_inotify_remove_from_idr(struct fsnotify_group *group,
struct inotify_inode_mark *i_mark)
{
struct idr *idr = &group->inotify_data.idr;
spinlock_t *idr_lock = &group->inotify_data.idr_lock;
int wd = i_mark->wd;
assert_spin_locked(idr_lock);
idr_remove(idr, wd);
/* removed from the idr, drop that ref */
fsnotify_put_mark(&i_mark->fsn_mark);
}
/*
* Remove the mark from the idr (if present) and drop the reference
* on the mark because it was in the idr.
@ -417,6 +402,7 @@ static void do_inotify_remove_from_idr(struct fsnotify_group *group,
static void inotify_remove_from_idr(struct fsnotify_group *group,
struct inotify_inode_mark *i_mark)
{
struct idr *idr = &group->inotify_data.idr;
spinlock_t *idr_lock = &group->inotify_data.idr_lock;
struct inotify_inode_mark *found_i_mark = NULL;
int wd;
@ -468,13 +454,15 @@ static void inotify_remove_from_idr(struct fsnotify_group *group,
BUG();
}
do_inotify_remove_from_idr(group, i_mark);
idr_remove(idr, wd);
/* Removed from the idr, drop that ref. */
fsnotify_put_mark(&i_mark->fsn_mark);
out:
i_mark->wd = -1;
spin_unlock(idr_lock);
/* match the ref taken by inotify_idr_find_locked() */
if (found_i_mark)
fsnotify_put_mark(&found_i_mark->fsn_mark);
i_mark->wd = -1;
spin_unlock(idr_lock);
}
/*