xfs: track preallocation separately in xfs_bmapi_reserve_delalloc()

Source kernel commit: 974ae922efd93b07b6cdf989ae959883f6f05fd8

Speculative preallocation is currently processed entirely by the callers
of xfs_bmapi_reserve_delalloc(). The caller determines how much
preallocation to include, adjusts the extent length and passes down the
resulting request.

While this works fine for post-eof speculative preallocation, it is not
as reliable for COW fork preallocation. COW fork preallocation is
implemented via the cowextszhint, which aligns the start offset as well
as the length of the extent. Further, it is difficult for the caller to
accurately identify when preallocation occurs because the returned
extent could have been merged with neighboring extents in the fork.

To simplify this situation and facilitate further COW fork preallocation
enhancements, update xfs_bmapi_reserve_delalloc() to take a separate
preallocation parameter to incorporate into the allocation request. The
preallocation blocks value is tacked onto the end of the request and
adjusted to accommodate neighboring extents and extent size limits.
Since xfs_bmapi_reserve_delalloc() now knows precisely how much
preallocation was included in the allocation, it can also tag the inodes
appropriately to support preallocation reclaim.

Note that xfs_bmapi_reserve_delalloc() callers are not yet updated to
use the preallocation mechanism. This patch should not change behavior
outside of correctly tagging reflink inodes when start offset
preallocation occurs (which the caller does not handle correctly).

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/libxfs/libxfs_priv.h b/libxfs/libxfs_priv.h
index f4db1833a95fbda93489b348b2460f5de1e20ff8..0c4baa809d775cfdfeb1285b60133cf6d0767b21 100644 (file)
--- a/libxfs/libxfs_priv.h
+++ b/libxfs/libxfs_priv.h
@@ -517,4 +517,8 @@ int libxfs_zero_extent(struct xfs_inode *ip, xfs_fsblock_t start_fsb,
 
 bool xfs_log_check_lsn(struct xfs_mount *, xfs_lsn_t);
 
+/* xfs_icache.c */
+#define xfs_inode_set_cowblocks_tag(ip)
+#define xfs_inode_set_eofblocks_tag(ip)
+
 #endif /* __LIBXFS_INTERNAL_XFS_H__ */

diff --git a/libxfs/xfs_bmap.c b/libxfs/xfs_bmap.c
index 4c730b90b976bce4dd19880a7204fe981313b2e3..316d8acf582db37e49666e441b4736e5ceb9ca64 100644 (file)
--- a/libxfs/xfs_bmap.c
+++ b/libxfs/xfs_bmap.c
@@ -4146,8 +4146,9 @@ int
 xfs_bmapi_reserve_delalloc(
        struct xfs_inode        *ip,
        int                     whichfork,
-       xfs_fileoff_t           aoff,
+       xfs_fileoff_t           off,
        xfs_filblks_t           len,
+       xfs_filblks_t           prealloc,
        struct xfs_bmbt_irec    *got,
        xfs_extnum_t            *lastx,
        int                     eof)
@@ -4159,10 +4160,17 @@ xfs_bmapi_reserve_delalloc(
        char                    rt = XFS_IS_REALTIME_INODE(ip);
        xfs_extlen_t            extsz;
        int                     error;
+       xfs_fileoff_t           aoff = off;
 
-       alen = XFS_FILBLKS_MIN(len, MAXEXTLEN);
+       /*
+        * Cap the alloc length. Keep track of prealloc so we know whether to
+        * tag the inode before we return.
+        */
+       alen = XFS_FILBLKS_MIN(len + prealloc, MAXEXTLEN);
        if (!eof)
                alen = XFS_FILBLKS_MIN(alen, got->br_startoff - aoff);
+       if (prealloc && alen >= len)
+               prealloc = alen - len;
 
        /* Figure out the extent size, adjust alen */
        if (whichfork == XFS_COW_FORK)
@@ -4228,6 +4236,16 @@ xfs_bmapi_reserve_delalloc(
         */
        xfs_bmbt_get_all(xfs_iext_get_ext(ifp, *lastx), got);
 
+       /*
+        * Tag the inode if blocks were preallocated. Note that COW fork
+        * preallocation can occur at the start or end of the extent, even when
+        * prealloc == 0, so we must also check the aligned offset and length.
+        */
+       if (whichfork == XFS_DATA_FORK && prealloc)
+               xfs_inode_set_eofblocks_tag(ip);
+       if (whichfork == XFS_COW_FORK && (prealloc || aoff < off || alen > len))
+               xfs_inode_set_cowblocks_tag(ip);
+
        ASSERT(got->br_startoff <= aoff);
        ASSERT(got->br_startoff + got->br_blockcount >= aoff + alen);
        ASSERT(isnullstartblock(got->br_startblock));

diff --git a/libxfs/xfs_bmap.h b/libxfs/xfs_bmap.h
index ffed1f9208ced972352a28671f470d6fd6be58d3..cecd094404cc53d821567be873bafdbba98880fa 100644 (file)
--- a/libxfs/xfs_bmap.h
+++ b/libxfs/xfs_bmap.h
@@ -238,7 +238,7 @@ int xfs_bmap_shift_extents(struct xfs_trans *tp, struct xfs_inode *ip,
                int num_exts);
 int    xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
 int    xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
-               xfs_fileoff_t aoff, xfs_filblks_t len,
+               xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc,
                struct xfs_bmbt_irec *got, xfs_extnum_t *lastx, int eof);
 
 enum xfs_bmap_intent_type {