6.8-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit dad80c6bff770d25f67ec25fe011730e4a463008 ]
During mount, cifs_mount_get_tcon() gets a tcon resource connection record and then attaches an fscache volume cookie to it. However, it does this irrespective of whether or not the tcon returned from cifs_get_tcon() is a new record or one that's already in use. This leads to a warning about a volume cookie collision and a leaked volume cookie because tcon->fscache gets reset.
Fix this be adding a mutex and a "we've already tried this" flag and only doing it once for the lifetime of the tcon.
[!] Note: Looking at cifs_mount_get_tcon(), a more general solution may actually be required. Reacquiring the volume cookie isn't the only thing that function does: it also partially reinitialises the tcon record without any locking - which may cause live filesystem ops already using the tcon through a previous mount to malfunction.
This can be reproduced simply by something like:
mount //example.com/test /xfstest.test -o user=shares,pass=xxx,fsc mount //example.com/test /mnt -o user=shares,pass=xxx,fsc
Fixes: 70431bfd825d ("cifs: Support fscache indexing rewrite") Signed-off-by: David Howells dhowells@redhat.com Acked-by: Paulo Alcantara (Red Hat) pc@manguebit.com cc: Shyam Prasad N sprasad@microsoft.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/cifsglob.h | 2 ++ fs/smb/client/fscache.c | 13 +++++++++++++ fs/smb/client/misc.c | 3 +++ 3 files changed, 18 insertions(+)
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h index 844afda090d05..0c3311de5dc0a 100644 --- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -1261,7 +1261,9 @@ struct cifs_tcon { __u32 max_cached_dirs; #ifdef CONFIG_CIFS_FSCACHE u64 resource_id; /* server resource id */ + bool fscache_acquired; /* T if we've tried acquiring a cookie */ struct fscache_volume *fscache; /* cookie for share */ + struct mutex fscache_lock; /* Prevent regetting a cookie */ #endif struct list_head pending_opens; /* list of incomplete opens */ struct cached_fids *cfids; diff --git a/fs/smb/client/fscache.c b/fs/smb/client/fscache.c index 340efce8f0529..113bde8f1e613 100644 --- a/fs/smb/client/fscache.c +++ b/fs/smb/client/fscache.c @@ -43,12 +43,23 @@ int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon) char *key; int ret = -ENOMEM;
+ if (tcon->fscache_acquired) + return 0; + + mutex_lock(&tcon->fscache_lock); + if (tcon->fscache_acquired) { + mutex_unlock(&tcon->fscache_lock); + return 0; + } + tcon->fscache_acquired = true; + tcon->fscache = NULL; switch (sa->sa_family) { case AF_INET: case AF_INET6: break; default: + mutex_unlock(&tcon->fscache_lock); cifs_dbg(VFS, "Unknown network family '%d'\n", sa->sa_family); return -EINVAL; } @@ -57,6 +68,7 @@ int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
sharename = extract_sharename(tcon->tree_name); if (IS_ERR(sharename)) { + mutex_unlock(&tcon->fscache_lock); cifs_dbg(FYI, "%s: couldn't extract sharename\n", __func__); return PTR_ERR(sharename); } @@ -90,6 +102,7 @@ int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon) kfree(key); out: kfree(sharename); + mutex_unlock(&tcon->fscache_lock); return ret; }
diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c index 74627d647818a..0d13db80e67c9 100644 --- a/fs/smb/client/misc.c +++ b/fs/smb/client/misc.c @@ -141,6 +141,9 @@ tcon_info_alloc(bool dir_leases_enabled) atomic_set(&ret_buf->num_local_opens, 0); atomic_set(&ret_buf->num_remote_opens, 0); ret_buf->stats_from_time = ktime_get_real_seconds(); +#ifdef CONFIG_CIFS_FSCACHE + mutex_init(&ret_buf->fscache_lock); +#endif
return ret_buf; }