Merge tag 'for-6.17-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- fix a few races related to inode link count
- fix inode leak on failure to add link to inode
- move transaction aborts closer to where they happen
* tag 'for-6.17-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: avoid load/store tearing races when checking if an inode was logged
btrfs: fix race between setting last_dir_index_offset and inode logging
btrfs: fix race between logging inode and checking if it was logged before
btrfs: simplify error handling logic for btrfs_link()
btrfs: fix inode leak on failure to add link to inode
btrfs: abort transaction on failure to add link to inode
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index b99fb02..0387b9f 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -248,7 +248,7 @@ struct btrfs_inode {
u64 new_delalloc_bytes;
/*
* The offset of the last dir index key that was logged.
- * This is used only for directories.
+ * This is used only for directories. Protected by 'log_mutex'.
*/
u64 last_dir_index_offset;
};
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 9e4aec7..dd82dcc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6805,7 +6805,6 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
struct fscrypt_name fname;
u64 index;
int ret;
- int drop_inode = 0;
/* do not allow sys_link's with other subvols of the same device */
if (btrfs_root_id(root) != btrfs_root_id(BTRFS_I(inode)->root))
@@ -6837,44 +6836,44 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
/* There are several dir indexes for this inode, clear the cache. */
BTRFS_I(inode)->dir_index = 0ULL;
- inc_nlink(inode);
inode_inc_iversion(inode);
inode_set_ctime_current(inode);
- ihold(inode);
set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
ret = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode),
&fname.disk_name, 1, index);
+ if (ret)
+ goto fail;
+ /* Link added now we update the inode item with the new link count. */
+ inc_nlink(inode);
+ ret = btrfs_update_inode(trans, BTRFS_I(inode));
if (ret) {
- drop_inode = 1;
- } else {
- struct dentry *parent = dentry->d_parent;
-
- ret = btrfs_update_inode(trans, BTRFS_I(inode));
- if (ret)
- goto fail;
- if (inode->i_nlink == 1) {
- /*
- * If new hard link count is 1, it's a file created
- * with open(2) O_TMPFILE flag.
- */
- ret = btrfs_orphan_del(trans, BTRFS_I(inode));
- if (ret)
- goto fail;
- }
- d_instantiate(dentry, inode);
- btrfs_log_new_name(trans, old_dentry, NULL, 0, parent);
+ btrfs_abort_transaction(trans, ret);
+ goto fail;
}
+ if (inode->i_nlink == 1) {
+ /*
+ * If the new hard link count is 1, it's a file created with the
+ * open(2) O_TMPFILE flag.
+ */
+ ret = btrfs_orphan_del(trans, BTRFS_I(inode));
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ goto fail;
+ }
+ }
+
+ /* Grab reference for the new dentry passed to d_instantiate(). */
+ ihold(inode);
+ d_instantiate(dentry, inode);
+ btrfs_log_new_name(trans, old_dentry, NULL, 0, dentry->d_parent);
+
fail:
fscrypt_free_filename(&fname);
if (trans)
btrfs_end_transaction(trans);
- if (drop_inode) {
- inode_dec_link_count(inode);
- iput(inode);
- }
btrfs_btree_balance_dirty(fs_info);
return ret;
}
@@ -7830,6 +7829,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
ei->last_sub_trans = 0;
ei->logged_trans = 0;
ei->delalloc_bytes = 0;
+ /* new_delalloc_bytes and last_dir_index_offset are in a union. */
ei->new_delalloc_bytes = 0;
ei->defrag_bytes = 0;
ei->disk_i_size = 0;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 69e1155..7d5d908 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3340,6 +3340,31 @@ int btrfs_free_log_root_tree(struct btrfs_trans_handle *trans,
return 0;
}
+static bool mark_inode_as_not_logged(const struct btrfs_trans_handle *trans,
+ struct btrfs_inode *inode)
+{
+ bool ret = false;
+
+ /*
+ * Do this only if ->logged_trans is still 0 to prevent races with
+ * concurrent logging as we may see the inode not logged when
+ * inode_logged() is called but it gets logged after inode_logged() did
+ * not find it in the log tree and we end up setting ->logged_trans to a
+ * value less than trans->transid after the concurrent logging task has
+ * set it to trans->transid. As a consequence, subsequent rename, unlink
+ * and link operations may end up not logging new names and removing old
+ * names from the log.
+ */
+ spin_lock(&inode->lock);
+ if (inode->logged_trans == 0)
+ inode->logged_trans = trans->transid - 1;
+ else if (inode->logged_trans == trans->transid)
+ ret = true;
+ spin_unlock(&inode->lock);
+
+ return ret;
+}
+
/*
* Check if an inode was logged in the current transaction. This correctly deals
* with the case where the inode was logged but has a logged_trans of 0, which
@@ -3357,15 +3382,32 @@ static int inode_logged(const struct btrfs_trans_handle *trans,
struct btrfs_key key;
int ret;
- if (inode->logged_trans == trans->transid)
+ /*
+ * Quick lockless call, since once ->logged_trans is set to the current
+ * transaction, we never set it to a lower value anywhere else.
+ */
+ if (data_race(inode->logged_trans) == trans->transid)
return 1;
/*
- * If logged_trans is not 0, then we know the inode logged was not logged
- * in this transaction, so we can return false right away.
+ * If logged_trans is not 0 and not trans->transid, then we know the
+ * inode was not logged in this transaction, so we can return false
+ * right away. We take the lock to avoid a race caused by load/store
+ * tearing with a concurrent btrfs_log_inode() call or a concurrent task
+ * in this function further below - an update to trans->transid can be
+ * teared into two 32 bits updates for example, in which case we could
+ * see a positive value that is not trans->transid and assume the inode
+ * was not logged when it was.
*/
- if (inode->logged_trans > 0)
+ spin_lock(&inode->lock);
+ if (inode->logged_trans == trans->transid) {
+ spin_unlock(&inode->lock);
+ return 1;
+ } else if (inode->logged_trans > 0) {
+ spin_unlock(&inode->lock);
return 0;
+ }
+ spin_unlock(&inode->lock);
/*
* If no log tree was created for this root in this transaction, then
@@ -3374,10 +3416,8 @@ static int inode_logged(const struct btrfs_trans_handle *trans,
* transaction's ID, to avoid the search below in a future call in case
* a log tree gets created after this.
*/
- if (!test_bit(BTRFS_ROOT_HAS_LOG_TREE, &inode->root->state)) {
- inode->logged_trans = trans->transid - 1;
- return 0;
- }
+ if (!test_bit(BTRFS_ROOT_HAS_LOG_TREE, &inode->root->state))
+ return mark_inode_as_not_logged(trans, inode);
/*
* We have a log tree and the inode's logged_trans is 0. We can't tell
@@ -3431,8 +3471,7 @@ static int inode_logged(const struct btrfs_trans_handle *trans,
* Set logged_trans to a value greater than 0 and less then the
* current transaction to avoid doing the search in future calls.
*/
- inode->logged_trans = trans->transid - 1;
- return 0;
+ return mark_inode_as_not_logged(trans, inode);
}
/*
@@ -3440,20 +3479,9 @@ static int inode_logged(const struct btrfs_trans_handle *trans,
* the current transacion's ID, to avoid future tree searches as long as
* the inode is not evicted again.
*/
+ spin_lock(&inode->lock);
inode->logged_trans = trans->transid;
-
- /*
- * If it's a directory, then we must set last_dir_index_offset to the
- * maximum possible value, so that the next attempt to log the inode does
- * not skip checking if dir index keys found in modified subvolume tree
- * leaves have been logged before, otherwise it would result in attempts
- * to insert duplicate dir index keys in the log tree. This must be done
- * because last_dir_index_offset is an in-memory only field, not persisted
- * in the inode item or any other on-disk structure, so its value is lost
- * once the inode is evicted.
- */
- if (S_ISDIR(inode->vfs_inode.i_mode))
- inode->last_dir_index_offset = (u64)-1;
+ spin_unlock(&inode->lock);
return 1;
}
@@ -4045,7 +4073,7 @@ static noinline int log_dir_items(struct btrfs_trans_handle *trans,
/*
* If the inode was logged before and it was evicted, then its
- * last_dir_index_offset is (u64)-1, so we don't the value of the last index
+ * last_dir_index_offset is 0, so we don't know the value of the last index
* key offset. If that's the case, search for it and update the inode. This
* is to avoid lookups in the log tree every time we try to insert a dir index
* key from a leaf changed in the current transaction, and to allow us to always
@@ -4061,7 +4089,7 @@ static int update_last_dir_index_offset(struct btrfs_inode *inode,
lockdep_assert_held(&inode->log_mutex);
- if (inode->last_dir_index_offset != (u64)-1)
+ if (inode->last_dir_index_offset != 0)
return 0;
if (!ctx->logged_before) {
