1 files changed, 22 insertions, 9 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index dc6eb088d73e..9fd0348be7f5 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -5526,16 +5526,29 @@ log_extents:
 		spin_lock(&inode->lock);
 		inode->logged_trans = trans->transid;
 		/*
-		 * Don't update last_log_commit if we logged that an inode exists
-		 * after it was loaded to memory (full_sync bit set).
-		 * This is to prevent data loss when we do a write to the inode,
-		 * then the inode gets evicted after all delalloc was flushed,
-		 * then we log it exists (due to a rename for example) and then
-		 * fsync it. This last fsync would do nothing (not logging the
-		 * extents previously written).
+		 * Don't update last_log_commit if we logged that an inode exists.
+		 * We do this for two reasons:
+		 *
+		 * 1) We might have had buffered writes to this inode that were
+		 *    flushed and had their ordered extents completed in this
+		 *    transaction, but we did not previously log the inode with
+		 *    LOG_INODE_ALL. Later the inode was evicted and after that
+		 *    it was loaded again and this LOG_INODE_EXISTS log operation
+		 *    happened. We must make sure that if an explicit fsync against
+		 *    the inode is performed later, it logs the new extents, an
+		 *    updated inode item, etc, and syncs the log. The same logic
+		 *    applies to direct IO writes instead of buffered writes.
+		 *
+		 * 2) When we log the inode with LOG_INODE_EXISTS, its inode item
+		 *    is logged with an i_size of 0 or whatever value was logged
+		 *    before. If later the i_size of the inode is increased by a
+		 *    truncate operation, the log is synced through an fsync of
+		 *    some other inode and then finally an explicit fsync against
+		 *    this inode is made, we must make sure this fsync logs the
+		 *    inode with the new i_size, the hole between old i_size and
+		 *    the new i_size, and syncs the log.
 		 */
-		if (inode_only != LOG_INODE_EXISTS ||
-		    !test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags))
+		if (inode_only != LOG_INODE_EXISTS)
 			inode->last_log_commit = inode->last_sub_trans;
 		spin_unlock(&inode->lock);
 	}