Commit a2182743 authored by Paul Aurich's avatar Paul Aurich Committed by Steve French
Browse files

smb: Log an error when close_all_cached_dirs fails 



Under low-memory conditions, close_all_cached_dirs() can't move the
dentries to a separate list to dput() them once the locks are dropped.
This will result in a "Dentry still in use" error, so add an error
message that makes it clear this is what happened:

[  495.281119] CIFS: VFS: \\otters.example.com\share Out of memory while dropping dentries
[  495.281595] ------------[ cut here ]------------
[  495.281887] BUG: Dentry ffff888115531138{i=78,n=/}  still in use (2) [unmount of cifs cifs]
[  495.282391] WARNING: CPU: 1 PID: 2329 at fs/dcache.c:1536 umount_check+0xc8/0xf0

Also, bail out of looping through all tcons as soon as a single
allocation fails, since we're already in trouble, and kmalloc() attempts
for subseqeuent tcons are likely to fail just like the first one did.

Signed-off-by: default avatarPaul Aurich <paul@darkrain42.org>
Acked-by: default avatarBharath SM <bharathsm@microsoft.com>
Suggested-by: default avatarRuben Devos <rdevos@oxya.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 2c4fd3d1

fs/smb/client/cached_dir.c

+12 −2
Original line number Diff line number Diff line
@@ -509,8 +509,17 @@ void close_all_cached_dirs(struct cifs_sb_info *cifs_sb) 
		spin_lock(&cfids->cfid_list_lock);

		list_for_each_entry(cfid, &cfids->entries, entry) {

			tmp_list = kmalloc(sizeof(*tmp_list), GFP_ATOMIC);

			if (tmp_list == NULL)

				break;

			if (tmp_list == NULL) {

				/*

				 * If the malloc() fails, we won't drop all

				 * dentries, and unmounting is likely to trigger

				 * a 'Dentry still in use' error.

				 */

				cifs_tcon_dbg(VFS, "Out of memory while dropping dentries\n");

				spin_unlock(&cfids->cfid_list_lock);

				spin_unlock(&cifs_sb->tlink_tree_lock);

				goto done;

			}

			spin_lock(&cfid->fid_lock);

			tmp_list->dentry = cfid->dentry;

			cfid->dentry = NULL;
@@ -522,6 +531,7 @@ void close_all_cached_dirs(struct cifs_sb_info *cifs_sb) 
	}

	spin_unlock(&cifs_sb->tlink_tree_lock);



done:

	list_for_each_entry_safe(tmp_list, q, &entry, entry) {

		list_del(&tmp_list->entry);

		dput(tmp_list->dentry);