[patch] xfsprogs: unhandled error check in libxfs_trans_read_buf

[Ajeet Yadav <ajeet.yadav.77@xxxxxxxxx>]

xfsprogs: unhandled error check in libxfs_trans_read_buf

libxfs_trans_read_buf() is used in both mkfs.xfs & xfs_repair.
During stability testing we found some time occur pagefault in mkfs.xfs,
code inspection shows that if libxfs_readbuf() fails then occurs a
page fault in xfs_buf_item_init() called in libxfs_trans_read_buf().

mkfs.xfs: unhandled page fault (11) at 0x00000070, code 0x017

Added NULL check and errno handling.

Signed-off-by: Ajeet Yadav <ajeet.yadav.77@xxxxxxxxx>

diff -Nurp xfsprogs/libxfs/rdwr.c xfsprogs-dirty/libxfs/rdwr.c
--- xfsprogs/libxfs/rdwr.c      2011-01-28 20:22:11.000000000 +0900
+++ xfsprogs-dirty/libxfs/rdwr.c        2011-02-02 16:59:16.000000000 +0900
@@ -207,10 +207,11 @@ libxfs_trace_readbuf(const char *func, c
 {
        xfs_buf_t       *bp = libxfs_readbuf(dev, blkno, len, flags);

-       bp->b_func = func;
-       bp->b_file = file;
-       bp->b_line = line;
-
+       if (bp){
+               bp->b_func = func;
+               bp->b_file = file;
+               bp->b_line = line;
+       }
        return bp;
 }

@@ -485,6 +486,7 @@ libxfs_readbuf(dev_t dev, xfs_daddr_t bl
                error = libxfs_readbufr(dev, blkno, bp, len, flags);
                if (error) {
                        libxfs_putbuf(bp);
+                       errno = error;
                        return NULL;
                }
        }
diff -Nurp xfsprogs/libxfs/trans.c xfsprogs-dirty/libxfs/trans.c
--- xfsprogs/libxfs/trans.c     2011-01-28 20:22:11.000000000 +0900
+++ xfsprogs-dirty/libxfs/trans.c       2011-02-02 17:00:42.000000000 +0900
@@ -508,6 +508,10 @@ libxfs_trans_read_buf(
        }

        bp = libxfs_readbuf(dev, blkno, len, flags);
+       if (!bp){
+               *bpp = NULL;
+               return errno;
+       }
 #ifdef XACT_DEBUG
        fprintf(stderr, "trans_read_buf buffer %p, transaction %p\n", bp, tp);
 #endif