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-rw-r--r--fs/btrfs/btrfs_inode.h6
-rw-r--r--fs/btrfs/inode.c17
-rw-r--r--fs/btrfs/tree-log.c16
3 files changed, 39 insertions, 0 deletions
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index fc25607304f2..6f5d07415dab 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -148,6 +148,12 @@ struct btrfs_inode {
u64 last_unlink_trans;
/*
+ * Track the transaction id of the last transaction used to create a
+ * hard link for the inode. This is used by the log tree (fsync).
+ */
+ u64 last_link_trans;
+
+ /*
* Number of bytes outstanding that are going to need csums. This is
* used in ENOSPC accounting.
*/
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d54bdef16d8d..b4129d9072ec 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3658,6 +3658,21 @@ cache_index:
* inode is not a directory, logging its parent unnecessarily.
*/
BTRFS_I(inode)->last_unlink_trans = BTRFS_I(inode)->last_trans;
+ /*
+ * Similar reasoning for last_link_trans, needs to be set otherwise
+ * for a case like the following:
+ *
+ * mkdir A
+ * touch foo
+ * ln foo A/bar
+ * echo 2 > /proc/sys/vm/drop_caches
+ * fsync foo
+ * <power failure>
+ *
+ * Would result in link bar and directory A not existing after the power
+ * failure.
+ */
+ BTRFS_I(inode)->last_link_trans = BTRFS_I(inode)->last_trans;
path->slots[0]++;
if (inode->i_nlink != 1 ||
@@ -6597,6 +6612,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
if (err)
goto fail;
}
+ BTRFS_I(inode)->last_link_trans = trans->transid;
d_instantiate(dentry, inode);
ret = btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent,
true, NULL);
@@ -9123,6 +9139,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
ei->index_cnt = (u64)-1;
ei->dir_index = 0;
ei->last_unlink_trans = 0;
+ ei->last_link_trans = 0;
ei->last_log_commit = 0;
spin_lock_init(&ei->lock);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 013d0abcd46b..5baad9bebc62 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -5758,6 +5758,22 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
goto end_trans;
}
+ /*
+ * If a new hard link was added to the inode in the current transaction
+ * and its link count is now greater than 1, we need to fallback to a
+ * transaction commit, otherwise we can end up not logging all its new
+ * parents for all the hard links. Here just from the dentry used to
+ * fsync, we can not visit the ancestor inodes for all the other hard
+ * links to figure out if any is new, so we fallback to a transaction
+ * commit (instead of adding a lot of complexity of scanning a btree,
+ * since this scenario is not a common use case).
+ */
+ if (inode->vfs_inode.i_nlink > 1 &&
+ inode->last_link_trans > last_committed) {
+ ret = -EMLINK;
+ goto end_trans;
+ }
+
while (1) {
if (!parent || d_really_is_negative(parent) || sb != parent->d_sb)
break;