From: NeilBrown <neilb@xxxxxxx>
When a file is opened and created with open(..., O_CREAT) we get
both the CREATE and OPEN fsnotify events and would expect them in that
order. For most filesystems we get them in that order because
open_last_lookups() calls fsnofify_create() and then do_open() (from
path_openat()) calls vfs_open()->do_dentry_open() which calls
fsnotify_open().
However when ->atomic_open is used, the
do_dentry_open() -> fsnotify_open()
call happens from finish_open() which is called from the ->atomic_open
handler in lookup_open() which is called *before* open_last_lookups()
calls fsnotify_create. So we get the "open" notification before
"create" - which is backwards. ltp testcase inotify02 tests this and
reports the inconsistency.
This patch lifts the fsnotify_open() call out of do_dentry_open() and
places it higher up the call stack. There are three callers of
do_dentry_open().
For vfs_open() and kernel_file_open() the fsnotify_open() is placed
directly in that caller so there should be no behavioural change.
For finish_open() there are two cases:
- finish_open is used in ->atomic_open handlers. For these we add a
call to fsnotify_open() at open_last_lookups() if FMODE_OPENED is
set - which means do_dentry_open() has been called.
- finish_open is used in ->tmpfile() handlers. For these a similar
call to fsnotify_open() is added to vfs_tmpfile()
With this patch NFSv3 is restored to its previous behaviour (before
->atomic_open support was added) of generating CREATE notifications
before OPEN, and NFSv4 now has that same correct ordering that is has
not had before. I haven't tested other filesystems.
Fixes: 7c6c5249f061 ("NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.")
Reported-by: James Clark <james.clark@xxxxxxx>
Closes: https://lore.kernel.org/all/01c3bf2e-eb1f-4b7f-a54f-d2a05dd3d8c8@xxxxxxx
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Link: https://lore.kernel.org/r/171817619547.14261.975798725161704336@xxxxxxxxxxxxxxxxxxxxx
Fixes: 7b8c9d7bb457 ("fsnotify: move fsnotify_open() hook into do_dentry_open()")
Tested-by: James Clark <james.clark@xxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/namei.c | 10 ++++++++--
fs/open.c | 22 +++++++++++++++-------
2 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 37fb0a8aa09a..1e05a0f3f04d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3572,8 +3572,12 @@ static const char *open_last_lookups(struct nameidata *nd,
else
inode_lock_shared(dir->d_inode);
dentry = lookup_open(nd, file, op, got_write);
- if (!IS_ERR(dentry) && (file->f_mode & FMODE_CREATED))
- fsnotify_create(dir->d_inode, dentry);
+ if (!IS_ERR(dentry)) {
+ if (file->f_mode & FMODE_CREATED)
+ fsnotify_create(dir->d_inode, dentry);
+ if (file->f_mode & FMODE_OPENED)
+ fsnotify_open(file);
+ }
if (open_flag & O_CREAT)
inode_unlock(dir->d_inode);
else
@@ -3700,6 +3704,8 @@ int vfs_tmpfile(struct mnt_idmap *idmap,
mode = vfs_prepare_mode(idmap, dir, mode, mode, mode);
error = dir->i_op->tmpfile(idmap, dir, file, mode);
dput(child);
+ if (file->f_mode & FMODE_OPENED)
+ fsnotify_open(file);
if (error)
return error;
/* Don't check for other permissions, the inode was just created */
diff --git a/fs/open.c b/fs/open.c
index 89cafb572061..f1607729acb9 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1004,11 +1004,6 @@ static int do_dentry_open(struct file *f,
}
}
- /*
- * Once we return a file with FMODE_OPENED, __fput() will call
- * fsnotify_close(), so we need fsnotify_open() here for symmetry.
- */
- fsnotify_open(f);
return 0;
cleanup_all:
@@ -1085,8 +1080,19 @@ EXPORT_SYMBOL(file_path);
*/
int vfs_open(const struct path *path, struct file *file)
{
+ int ret;
+
file->f_path = *path;
- return do_dentry_open(file, NULL);
+ ret = do_dentry_open(file, NULL);
+ if (!ret) {
+ /*
+ * Once we return a file with FMODE_OPENED, __fput() will call
+ * fsnotify_close(), so we need fsnotify_open() here for
+ * symmetry.
+ */
+ fsnotify_open(file);
+ }
+ return ret;
}
struct file *dentry_open(const struct path *path, int flags,
@@ -1177,8 +1183,10 @@ struct file *kernel_file_open(const struct path *path, int flags,
error = do_dentry_open(f, NULL);
if (error) {
fput(f);
- f = ERR_PTR(error);
+ return ERR_PTR(error);
}
+
+ fsnotify_open(f);
return f;
}
EXPORT_SYMBOL_GPL(kernel_file_open);
--
2.35.3
