xfs: improve the xfs_dabuf_map calling conventions

Use a flags argument with the XFS_DABUF_MAP_HOLE_OK flag to signal that
a hole is okay and not corruption, and return 0 with *nmap set to 0 to
signal that case in the return value instead of a nameless -1 return
code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index e078817..4d582a3 100644 (file)
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -2460,19 +2460,11 @@ xfs_da_shrink_inode(
        return error;
 }
 
-/*
- * Map the block we are given ready for reading. There are three possible return
- * values:
- *     -1 - will be returned if we land in a hole and mappedbno == -2 so the
- *          caller knows not to execute a subsequent read.
- *      0 - if we mapped the block successfully
- *     >0 - positive error number if there was an error.
- */
 static int
 xfs_dabuf_map(
        struct xfs_inode        *dp,
        xfs_dablk_t             bno,
-       xfs_daddr_t             mappedbno,
+       unsigned int            flags,
        int                     whichfork,
        struct xfs_buf_map      **mapp,
        int                     *nmaps)
@@ -2527,7 +2519,7 @@ out_free_irecs:
 
 invalid_mapping:
        /* Caller ok with no mapping. */
-       if (XFS_IS_CORRUPT(mp, mappedbno != -2)) {
+       if (XFS_IS_CORRUPT(mp, !(flags & XFS_DABUF_MAP_HOLE_OK))) {
                error = -EFSCORRUPTED;
                if (xfs_error_level >= XFS_ERRLEVEL_LOW) {
                        xfs_alert(mp, "%s: bno %u inode %llu",
@@ -2575,13 +2567,11 @@ xfs_da_get_buf(
                goto done;
        }
 
-       error = xfs_dabuf_map(dp, bno, mappedbno, whichfork, &mapp, &nmap);
-       if (error) {
-               /* mapping a hole is not an error, but we don't continue */
-               if (error == -1)
-                       error = 0;
+       error = xfs_dabuf_map(dp, bno,
+                       mappedbno == -1 ? XFS_DABUF_MAP_HOLE_OK : 0,
+                       whichfork, &mapp, &nmap);
+       if (error || nmap == 0)
                goto out_free;
-       }
 
        bp = xfs_trans_get_buf_map(tp, mp->m_ddev_targp, mapp, nmap, 0);
 done:
@@ -2630,13 +2620,11 @@ xfs_da_read_buf(
                goto done;
        }
 
-       error = xfs_dabuf_map(dp, bno, mappedbno, whichfork, &mapp, &nmap);
-       if (error) {
-               /* mapping a hole is not an error, but we don't continue */
-               if (error == -1)
-                       error = 0;
+       error = xfs_dabuf_map(dp, bno,
+                       mappedbno == -1 ? XFS_DABUF_MAP_HOLE_OK : 0,
+                       whichfork, &mapp, &nmap);
+       if (error || !nmap)
                goto out_free;
-       }
 
        error = xfs_trans_read_buf_map(mp, tp, mp->m_ddev_targp, mapp, nmap, 0,
                        &bp, ops);
@@ -2677,14 +2665,11 @@ xfs_da_reada_buf(
 
        mapp = ↦
        nmap = 1;
-       error = xfs_dabuf_map(dp, bno, mappedbno, whichfork,
-                               &mapp, &nmap);
-       if (error) {
-               /* mapping a hole is not an error, but we don't continue */
-               if (error == -1)
-                       error = 0;
+       error = xfs_dabuf_map(dp, bno,
+                       mappedbno == -1 ? XFS_DABUF_MAP_HOLE_OK : 0,
+                       whichfork, &mapp, &nmap);
+       if (error || !nmap)
                goto out_free;
-       }
 
        mappedbno = mapp[0].bm_bn;
        xfs_buf_readahead_map(dp->i_mount->m_ddev_targp, mapp, nmap, ops);

diff --git a/fs/xfs/libxfs/xfs_da_btree.h b/fs/xfs/libxfs/xfs_da_btree.h
index ed3b558..64624d5 100644 (file)
--- a/fs/xfs/libxfs/xfs_da_btree.h
+++ b/fs/xfs/libxfs/xfs_da_btree.h
@@ -194,6 +194,9 @@ int xfs_da3_node_read(struct xfs_trans *tp, struct xfs_inode *dp,
 /*
  * Utility routines.
  */
+
+#define XFS_DABUF_MAP_HOLE_OK  (1 << 0)
+
 int    xfs_da_grow_inode(xfs_da_args_t *args, xfs_dablk_t *new_blkno);
 int    xfs_da_grow_inode_int(struct xfs_da_args *args, xfs_fileoff_t *bno,
                              int count);