ext4: add ext4_sb_bread() to disambiguate ENOMEM cases

Today, when sb_bread() returns NULL, this can either be because of an
I/O error or because the system failed to allocate the buffer.  Since
it's an old interface, changing would require changing many call
sites.

So instead we create our own ext4_sb_bread(), which also allows us to
set the REQ_META flag.

Also fixed a problem in the xattr code where a NULL return in a
function could also mean that the xattr was not found, which could
lead to the wrong error getting returned to userspace.

Fixes: ac27a0ec112a ("ext4: initial copy of files from ext3")
Cc: stable@kernel.org # 2.6.19
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 18 insertions, 18 deletions

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 61a9d1927817..a98bfca9c463 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -116,9 +116,9 @@ static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 	int i, retval = 0;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 
-	bh = sb_bread(inode->i_sb, pblock);
-	if (!bh)
-		return -EIO;
+	bh = ext4_sb_bread(inode->i_sb, pblock, 0);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 
 	i_data = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
@@ -145,9 +145,9 @@ static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 	int i, retval = 0;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 
-	bh = sb_bread(inode->i_sb, pblock);
-	if (!bh)
-		return -EIO;
+	bh = ext4_sb_bread(inode->i_sb, pblock, 0);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 
 	i_data = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
@@ -175,9 +175,9 @@ static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 	int i, retval = 0;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 
-	bh = sb_bread(inode->i_sb, pblock);
-	if (!bh)
-		return -EIO;
+	bh = ext4_sb_bread(inode->i_sb, pblock, 0);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 
 	i_data = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
@@ -224,9 +224,9 @@ static int free_dind_blocks(handle_t *handle,
 	struct buffer_head *bh;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 
-	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
-	if (!bh)
-		return -EIO;
+	bh = ext4_sb_bread(inode->i_sb, le32_to_cpu(i_data), 0);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 
 	tmp_idata = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
@@ -254,9 +254,9 @@ static int free_tind_blocks(handle_t *handle,
 	struct buffer_head *bh;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 
-	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
-	if (!bh)
-		return -EIO;
+	bh = ext4_sb_bread(inode->i_sb, le32_to_cpu(i_data), 0);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 
 	tmp_idata = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
@@ -382,9 +382,9 @@ static int free_ext_idx(handle_t *handle, struct inode *inode,
 	struct ext4_extent_header *eh;
 
 	block = ext4_idx_pblock(ix);
-	bh = sb_bread(inode->i_sb, block);
-	if (!bh)
-		return -EIO;
+	bh = ext4_sb_bread(inode->i_sb, block, 0);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
 
 	eh = (struct ext4_extent_header *)bh->b_data;
 	if (eh->eh_depth != 0) {