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smb: Log an error when close_all_cached_dirs fails

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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: Paul Aurich <paul@darkrain42.org>
Acked-by: Bharath SM <bharathsm@microsoft.com>
Suggested-by: Ruben Devos <rdevos@oxya.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paul Aurich 2024-11-20 08:01:54 -08:00 committed by Steve French
parent 2c4fd3d141
commit a2182743a8
1 changed files with 12 additions and 2 deletions
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14
fs/smb/client/cached_dir.c
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@ -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);