xfs: uncached buffer reads need to return an error

With verification being done as an IO completion callback, different
errors can be returned from a read. Uncached reads only return a
buffer or NULL on failure, which means the verification error cannot
be returned to the caller.

Split the error handling for these reads into two - a failure to get
a buffer will still return NULL, but a read error will return a
referenced buffer with b_error set rather than NULL. The caller is
responsible for checking the error state of the buffer returned.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Phil White <pwhite@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

4 files changed, 21 insertions, 8 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 0298dd684798..fbc965fc075a 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -715,8 +715,7 @@ xfs_buf_read_uncached(
         int                     flags,
         xfs_buf_iodone_t        verify)
 {
-        xfs_buf_t               *bp;
-        int                     error;
+        struct xfs_buf          *bp;
 
         bp = xfs_buf_get_uncached(target, numblks, flags);
         if (!bp)
@@ -730,11 +729,7 @@ xfs_buf_read_uncached(
         bp->b_iodone = verify;
 
         xfsbdstrat(target->bt_mount, bp);
-        error = xfs_buf_iowait(bp);
-        if (error) {
-                xfs_buf_relse(bp);
-                return NULL;
-        }
+        xfs_buf_iowait(bp);
         return bp;
 }
 
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 5440768ec41c..f35f8d7731f0 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -171,6 +171,11 @@ xfs_growfs_data_private(
                                 XFS_FSS_TO_BB(mp, 1), 0, NULL);
         if (!bp)
                 return EIO;
+        if (bp->b_error) {
+                int     error = bp->b_error;
+                xfs_buf_relse(bp);
+                return error;
+        }
         xfs_buf_relse(bp);
 
         new = nb;       /* use new as a temporary here */
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index d5402b0eb6a3..df6d0b2aade1 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -658,6 +658,12 @@ reread:
                         xfs_warn(mp, "SB buffer read failed");
                 return EIO;
         }
+        if (bp->b_error) {
+                error = bp->b_error;
+                if (loud)
+                        xfs_warn(mp, "SB validate failed");
+                goto release_buf;
+        }
 
         /*
          * Initialize the mount structure from the superblock.
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index b271ed939d7b..98dc670d3ee0 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1876,6 +1876,11 @@ xfs_growfs_rt(
                                 XFS_FSB_TO_BB(mp, 1), 0, NULL);
         if (!bp)
                 return EIO;
+        if (bp->b_error) {
+                error = bp->b_error;
+                xfs_buf_relse(bp);
+                return error;
+        }
         xfs_buf_relse(bp);
 
         /*
@@ -2221,8 +2226,10 @@ xfs_rtmount_init(
         bp = xfs_buf_read_uncached(mp->m_rtdev_targp,
                                         d - XFS_FSB_TO_BB(mp, 1),
                                         XFS_FSB_TO_BB(mp, 1), 0, NULL);
-        if (!bp) {
+        if (!bp || bp->b_error) {
                 xfs_warn(mp, "realtime device size check failed");
+                if (bp)
+                        xfs_buf_relse(bp);
                 return EIO;
         }
         xfs_buf_relse(bp);