ext4: fix unjournalled bg descriptor while initializing inode bitmap

commit 61c219f upstream. The first time that we allocate from an uninitialized inode allocation bitmap, if the block allocation bitmap is also uninitalized, we need to get write access to the block group descriptor before we start modifying the block group descriptor flags and updating the free block count, etc. Otherwise, there is the potential of a bad journal checksum (if journal checksums are enabled), and of the file system becoming inconsistent if we crash at exactly the wrong time. Signed-off-by: Theodore Ts'o <[email protected]> Signed-off-by: Jiri Slaby <[email protected]>
koalo · Jul 18, 2014 · 95f670b · 95f670b
1 parent 07c0719
commit 95f670b
Showing 1 changed file with 7 additions and 7 deletions.
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
@@ -851,6 +851,13 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 		goto out;
 	}
 
+	BUFFER_TRACE(group_desc_bh, "get_write_access");
+	err = ext4_journal_get_write_access(handle, group_desc_bh);
+	if (err) {
+		ext4_std_error(sb, err);
+		goto out;
+	}
+
 	/* We may have to initialize the block bitmap if it isn't already */
 	if (ext4_has_group_desc_csum(sb) &&
 	    gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
@@ -887,13 +894,6 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 		}
 	}
 
-	BUFFER_TRACE(group_desc_bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, group_desc_bh);
-	if (err) {
-		ext4_std_error(sb, err);
-		goto out;
-	}
-
 	/* Update the relevant bg descriptor fields */
 	if (ext4_has_group_desc_csum(sb)) {
 		int free;