xfs: remove the imap_valid flag

Simplify the way we check for a valid imap - we know we have a valid
mapping after xfs_map_blocks returned successfully, and we know we can
call xfs_imap_valid on any imap, as it will always fail on a
zero-initialized map.

We can also remove the xfs_imap_valid function and fold it into
xfs_map_blocks now.

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

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 0bfcc2d06658e7f3ebbf4215d8d1f6ff839f955a..09092f10cff3e469256b3f79e507463d1597f86b 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -30,7 +30,6 @@
  */
 struct xfs_writepage_ctx {
        struct xfs_bmbt_irec    imap;
-       bool                    imap_valid;
        unsigned int            io_type;
        struct xfs_ioend        *ioend;
        sector_t                last_block;
@@ -370,15 +369,47 @@ xfs_map_blocks(
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
        ssize_t                 count = i_blocksize(inode);
-       xfs_fileoff_t           offset_fsb, end_fsb;
+       xfs_fileoff_t           offset_fsb = XFS_B_TO_FSBT(mp, offset), end_fsb;
        struct xfs_bmbt_irec    imap;
        int                     whichfork = XFS_DATA_FORK;
        struct xfs_iext_cursor  icur;
+       bool                    imap_valid;
        int                     error = 0;
 
+       /*
+        * We have to make sure the cached mapping is within EOF to protect
+        * against eofblocks trimming on file release leaving us with a stale
+        * mapping. Otherwise, a page for a subsequent file extending buffered
+        * write could get picked up by this writeback cycle and written to the
+        * wrong blocks.
+        *
+        * Note that what we really want here is a generic mapping invalidation
+        * mechanism to protect us from arbitrary extent modifying contexts, not
+        * just eofblocks.
+        */
+       xfs_trim_extent_eof(&wpc->imap, ip);
+
+       /*
+        * COW fork blocks can overlap data fork blocks even if the blocks
+        * aren't shared.  COW I/O always takes precedent, so we must always
+        * check for overlap on reflink inodes unless the mapping is already a
+        * COW one.
+        */
+       imap_valid = offset_fsb >= wpc->imap.br_startoff &&
+                    offset_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount;
+       if (imap_valid &&
+           (!xfs_is_reflink_inode(ip) || wpc->io_type == XFS_IO_COW))
+               return 0;
+
        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;
 
+       /*
+        * If we don't have a valid map, now it's time to get a new one for this
+        * offset.  This will convert delayed allocations (including COW ones)
+        * into real extents.  If we return without a valid map, it means we
+        * landed in a hole and we skip the block.
+        */
        xfs_ilock(ip, XFS_ILOCK_SHARED);
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
               (ip->i_df.if_flags & XFS_IFEXTENTS));
@@ -387,7 +418,6 @@ xfs_map_blocks(
        if (offset > mp->m_super->s_maxbytes - count)
                count = mp->m_super->s_maxbytes - offset;
        end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
-       offset_fsb = XFS_B_TO_FSBT(mp, offset);
 
        /*
         * Check if this is offset is covered by a COW extents, and if yes use
@@ -420,7 +450,7 @@ xfs_map_blocks(
        /*
         * Map valid and no COW extent in the way?  We're done.
         */
-       if (wpc->imap_valid) {
+       if (imap_valid) {
                xfs_iunlock(ip, XFS_ILOCK_SHARED);
                return 0;
        }
@@ -465,31 +495,6 @@ xfs_map_blocks(
        return 0;
 }
 
-STATIC bool
-xfs_imap_valid(
-       struct inode            *inode,
-       struct xfs_bmbt_irec    *imap,
-       xfs_off_t               offset)
-{
-       offset >>= inode->i_blkbits;
-
-       /*
-        * We have to make sure the cached mapping is within EOF to protect
-        * against eofblocks trimming on file release leaving us with a stale
-        * mapping. Otherwise, a page for a subsequent file extending buffered
-        * write could get picked up by this writeback cycle and written to the
-        * wrong blocks.
-        *
-        * Note that what we really want here is a generic mapping invalidation
-        * mechanism to protect us from arbitrary extent modifying contexts, not
-        * just eofblocks.
-        */
-       xfs_trim_extent_eof(imap, XFS_I(inode));
-
-       return offset >= imap->br_startoff &&
-               offset < imap->br_startoff + imap->br_blockcount;
-}
-
 STATIC void
 xfs_start_buffer_writeback(
        struct buffer_head      *bh)
@@ -856,27 +861,10 @@ xfs_writepage_map(
                        continue;
                }
 
-               if (wpc->imap_valid)
-                       wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap,
-                                                        file_offset);
-
-               /*
-                * COW fork blocks can overlap data fork blocks even if the
-                * blocks aren't shared. COW I/O always takes precedent, so we
-                * must always check for overlap on reflink inodes unless the
-                * mapping is already a COW one.
-                */
-               if (!wpc->imap_valid ||
-                   (xfs_is_reflink_inode(XFS_I(inode)) &&
-                    wpc->io_type != XFS_IO_COW)) {
-                       error = xfs_map_blocks(wpc, inode, file_offset);
-                       if (error)
-                               goto out;
-                       wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap,
-                                                        file_offset);
-               }
-
-               if (!wpc->imap_valid || wpc->io_type == XFS_IO_HOLE)
+               error = xfs_map_blocks(wpc, inode, file_offset);
+               if (error)
+                       break;
+               if (wpc->io_type == XFS_IO_HOLE)
                        continue;
 
                lock_buffer(bh);
@@ -887,7 +875,6 @@ xfs_writepage_map(
 
        ASSERT(wpc->ioend || list_empty(&submit_list));
 
-out:
        /*
         * On error, we have to fail the ioend here because we have locked
         * buffers in the ioend. If we don't do this, we'll deadlock