Btrfs: fix inode cache waiters hanging on failure to start caching thread

[ Upstream commit a68ebe0790fc88b4314d17984a2cf99ce2361901 ]

If we fail to start the inode caching thread, we print an error message
and disable the inode cache, however we never wake up any waiters, so they
hang forever waiting for the caching to finish. Fix this by waking them
up and have them fallback to a call to btrfs_find_free_objectid().

Fixes: e60efa84252c05 ("Btrfs: avoid triggering bug_on() when we fail to start inode caching task")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index 7dc2923655d98d12ca37de3e6a312d577b016372..b1c3a4ec76c8c243595b3707a4ec52ae15f54a7d 100644 (file)
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -26,6 +26,19 @@
 #include "inode-map.h"
 #include "transaction.h"
 
+static void fail_caching_thread(struct btrfs_root *root)
+{
+       struct btrfs_fs_info *fs_info = root->fs_info;
+
+       btrfs_warn(fs_info, "failed to start inode caching task");
+       btrfs_clear_pending_and_info(fs_info, INODE_MAP_CACHE,
+                                    "disabling inode map caching");
+       spin_lock(&root->ino_cache_lock);
+       root->ino_cache_state = BTRFS_CACHE_ERROR;
+       spin_unlock(&root->ino_cache_lock);
+       wake_up(&root->ino_cache_wait);
+}
+
 static int caching_kthread(void *data)
 {
        struct btrfs_root *root = data;
@@ -178,11 +191,8 @@ static void start_caching(struct btrfs_root *root)
 
        tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
                          root->root_key.objectid);
-       if (IS_ERR(tsk)) {
-               btrfs_warn(fs_info, "failed to start inode caching task");
-               btrfs_clear_pending_and_info(fs_info, INODE_MAP_CACHE,
-                                            "disabling inode map caching");
-       }
+       if (IS_ERR(tsk))
+               fail_caching_thread(root);
 }
 
 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
@@ -200,11 +210,14 @@ int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
 
        wait_event(root->ino_cache_wait,
                   root->ino_cache_state == BTRFS_CACHE_FINISHED ||
+                  root->ino_cache_state == BTRFS_CACHE_ERROR ||
                   root->free_ino_ctl->free_space > 0);
 
        if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
            root->free_ino_ctl->free_space == 0)
                return -ENOSPC;
+       else if (root->ino_cache_state == BTRFS_CACHE_ERROR)
+               return btrfs_find_free_objectid(root, objectid);
        else
                goto again;
 }