Used the per-fork sequence counter to avoid lookups in the writeback code
unless the COW fork actually changed.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_aops.c | 30 +++++++++++++++++++++++++-----
fs/xfs/xfs_iomap.c | 5 ++++-
fs/xfs/xfs_iomap.h | 2 +-
3 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 814100d27343..aff9d44fa338 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -29,6 +29,7 @@
struct xfs_writepage_ctx {
struct xfs_bmbt_irec imap;
unsigned int io_type;
+ unsigned int cow_seq;
struct xfs_ioend *ioend;
};
@@ -310,6 +311,7 @@ xfs_map_blocks(
struct xfs_mount *mp = ip->i_mount;
ssize_t count = i_blocksize(inode);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset), end_fsb;
+ xfs_fileoff_t cow_fsb = NULLFILEOFF;
struct xfs_bmbt_irec imap;
int whichfork = XFS_DATA_FORK;
struct xfs_iext_cursor icur;
@@ -333,12 +335,15 @@ xfs_map_blocks(
* 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.
+ * COW one, or the COW fork hasn't changed from the last time we looked
+ * at it.
*/
imap_valid = offset_fsb >= wpc->imap.br_startoff &&
offset_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount;
if (imap_valid &&
- (!xfs_inode_has_cow_data(ip) || wpc->io_type == XFS_IO_COW))
+ (!xfs_inode_has_cow_data(ip) ||
+ wpc->io_type == XFS_IO_COW ||
+ wpc->cow_seq == ip->i_cowfp->if_seq))
return 0;
if (XFS_FORCED_SHUTDOWN(mp))
@@ -364,8 +369,10 @@ xfs_map_blocks(
* it directly instead of looking up anything in the data fork.
*/
if (xfs_inode_has_cow_data(ip) &&
- xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap) &&
- imap.br_startoff <= offset_fsb) {
+ xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap))
+ cow_fsb = imap.br_startoff;
+ if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
+ wpc->cow_seq = ip->i_cowfp->if_seq;
xfs_iunlock(ip, XFS_ILOCK_SHARED);
/*
* Truncate can race with writeback since writeback doesn't
@@ -411,6 +418,16 @@ xfs_map_blocks(
imap.br_startblock = HOLESTARTBLOCK;
wpc->io_type = XFS_IO_HOLE;
} else {
+ /*
+ * Truncate to the next COW extent if there is one. This is the
+ * only opportunity to do this because we can skip COW fork
+ * lookups for the subsequent blocks in the mapping; however,
+ * the requirement to treat the COW range separately remains.
+ */
+ if (cow_fsb != NULLFILEOFF &&
+ cow_fsb < imap.br_startoff + imap.br_blockcount)
+ imap.br_blockcount = cow_fsb - imap.br_startoff;
+
if (isnullstartblock(imap.br_startblock)) {
/* got a delalloc extent */
wpc->io_type = XFS_IO_DELALLOC;
@@ -427,9 +444,12 @@ xfs_map_blocks(
trace_xfs_map_blocks_found(ip, offset, count, wpc->io_type, &imap);
return 0;
allocate_blocks:
- error = xfs_iomap_write_allocate(ip, whichfork, offset, &imap);
+ error = xfs_iomap_write_allocate(ip, whichfork, offset, &imap,
+ &wpc->cow_seq);
if (error)
return error;
+ ASSERT(whichfork == XFS_COW_FORK || cow_fsb == NULLFILEOFF ||
+ imap.br_startoff + imap.br_blockcount <= cow_fsb);
wpc->imap = imap;
trace_xfs_map_blocks_alloc(ip, offset, count, wpc->io_type, &imap);
return 0;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 756694219f77..43a7ff7f450c 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -658,7 +658,8 @@ xfs_iomap_write_allocate(
xfs_inode_t *ip,
int whichfork,
xfs_off_t offset,
- xfs_bmbt_irec_t *imap)
+ xfs_bmbt_irec_t *imap,
+ unsigned int *cow_seq)
{
xfs_mount_t *mp = ip->i_mount;
xfs_fileoff_t offset_fsb, last_block;
@@ -780,6 +781,8 @@ xfs_iomap_write_allocate(
if (error)
goto error0;
+ if (whichfork == XFS_COW_FORK)
+ *cow_seq = XFS_IFORK_PTR(ip, whichfork)->if_seq;
xfs_iunlock(ip, XFS_ILOCK_EXCL);
}
diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h
index 83474c9cede9..c6170548831b 100644
--- a/fs/xfs/xfs_iomap.h
+++ b/fs/xfs/xfs_iomap.h
@@ -14,7 +14,7 @@ struct xfs_bmbt_irec;
int xfs_iomap_write_direct(struct xfs_inode *, xfs_off_t, size_t,
struct xfs_bmbt_irec *, int);
int xfs_iomap_write_allocate(struct xfs_inode *, int, xfs_off_t,
- struct xfs_bmbt_irec *);
+ struct xfs_bmbt_irec *, unsigned int *);
int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, xfs_off_t, bool);
void xfs_bmbt_to_iomap(struct xfs_inode *, struct iomap *,
--
2.18.0
--
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