[PATCH 4/6] xfs: xfs_trans_read_buf() should return an error on failure

Dave Chinner
2011-03-23T06:12:54Z

From: Dave Chinner <dchinner@redhat.com>

When inside a transaction and we fail to read a buffer,
xfs_trans_read_buf returns a null buffer pointer and no error.
xfs_do_da_buf() checks the error return, but not the buffer, and as
a result this read failure condition causes a panic when it attempts
to dereference the non-existant buffer.

Make xfs_trans_read_buf() return the same error for this situation
regardless of whether it is in a transaction or not. This means
every caller does not need to check both the error return and the
buffer before proceeding to use the buffer.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_trans_buf.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 3bea661..03b3b7f 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -383,7 +383,8 @@ xfs_trans_read_buf(
bp = xfs_buf_read(target, blkno, len, flags | XBF_DONT_BLOCK);
if (bp == NULL) {
*bpp = NULL;
- return 0;
+ return (flags & XBF_TRYLOCK) ?
+ 0 : XFS_ERROR(ENOMEM);
}
if (XFS_BUF_GETERROR(bp) != 0) {
XFS_BUF_SUPER_STALE(bp);
--
1.7.2.3