Besides simplifying the code a bit this allows to actually implement
the behavior of using COW preallocation for non-COW data mentioned
in the current comments.
Note that this breaks the current version of xfs/420, but that is
because the test is broken. A separate fix will be sent for it.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_iomap.c | 135 +++++++++++++++++++++++++++++--------------
fs/xfs/xfs_reflink.c | 66 ---------------------
2 files changed, 92 insertions(+), 109 deletions(-)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index f982b183e05b..3e7f0ca78669 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -522,15 +522,16 @@ xfs_file_iomap_begin_delay(
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
- struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t maxbytes_fsb =
XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
xfs_fileoff_t end_fsb;
- int error = 0, eof = 0;
- struct xfs_bmbt_irec got;
- struct xfs_iext_cursor icur;
+ struct xfs_bmbt_irec imap, cmap;
+ struct xfs_iext_cursor icur, ccur;
xfs_fsblock_t prealloc_blocks = 0;
+ bool eof = false, cow_eof = false, shared;
+ int whichfork = XFS_DATA_FORK;
+ int error = 0;
ASSERT(!XFS_IS_REALTIME_INODE(ip));
ASSERT(!xfs_get_extsz_hint(ip));
@@ -548,7 +549,7 @@ xfs_file_iomap_begin_delay(
XFS_STATS_INC(mp, xs_blk_mapw);
- if (!(ifp->if_flags & XFS_IFEXTENTS)) {
+ if (!(ip->i_df.if_flags & XFS_IFEXTENTS)) {
error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
if (error)
goto out_unlock;
@@ -556,51 +557,97 @@ xfs_file_iomap_begin_delay(
end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
- eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
+ /*
+ * Search the data fork fork first to look up our source mapping. We
+ * always need the data fork map, as we have to return it to the
+ * iomap code so that the higher level write code can read data in to
+ * perform read-modify-write cycles for unaligned writes.
+ */
+ eof = !xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap);
if (eof)
- got.br_startoff = end_fsb; /* fake hole until the end */
+ imap.br_startoff = end_fsb; /* fake hole until the end */
- if (got.br_startoff <= offset_fsb) {
+ /* We never need to allocate blocks for zeroing a hole. */
+ if ((flags & IOMAP_ZERO) && imap.br_startoff > offset_fsb) {
+ xfs_hole_to_iomap(ip, iomap, offset_fsb, imap.br_startoff);
+ goto out_unlock;
+ }
+
+ /*
+ * Search the COW fork extent list even if we did not find a data fork
+ * extent. This serves two purposes: first this implements the
+ * speculative preallocation using cowextisze, so that we also unshare
+ * block adjacent to shared blocks instead of just the shared blocks
+ * themselves. Second the lookup in the extent list is generally faster
+ * than going out to the shared extent tree.
+ */
+ if (xfs_is_reflink_inode(ip)) {
+ cow_eof = !xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb,
+ &ccur, &cmap);
+ if (!cow_eof && cmap.br_startoff <= offset_fsb) {
+ if (imap.br_startoff <= offset_fsb) {
+ xfs_trim_extent(&imap, cmap.br_startoff,
+ cmap.br_blockcount);
+ } else {
+ xfs_trim_extent(&cmap, offset_fsb,
+ imap.br_startoff - offset_fsb);
+ imap = cmap;
+ }
+ trace_xfs_reflink_cow_found(ip, &imap);
+ goto done;
+ }
+ }
+
+ if (imap.br_startoff <= offset_fsb) {
/*
* For reflink files we may need a delalloc reservation when
* overwriting shared extents. This includes zeroing of
* existing extents that contain data.
*/
- if (xfs_is_reflink_inode(ip) &&
- ((flags & IOMAP_WRITE) ||
- got.br_state != XFS_EXT_UNWRITTEN)) {
- xfs_trim_extent(&got, offset_fsb, end_fsb - offset_fsb);
- error = xfs_reflink_reserve_cow(ip, &got);
- if (error)
- goto out_unlock;
+ if (!xfs_is_reflink_inode(ip) ||
+ ((flags & IOMAP_ZERO) && imap.br_state != XFS_EXT_NORM)) {
+ trace_xfs_iomap_found(ip, offset, count, 0, &imap);
+ goto done;
}
- trace_xfs_iomap_found(ip, offset, count, 0, &got);
- goto done;
- }
+ xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
- if (flags & IOMAP_ZERO) {
- xfs_hole_to_iomap(ip, iomap, offset_fsb, got.br_startoff);
- goto out_unlock;
+ /* Trim the mapping to the nearest shared extent boundary. */
+ error = xfs_reflink_trim_around_shared(ip, &imap, &shared);
+ if (error)
+ goto out_unlock;
+
+ /* Not shared? Just report the (potentially capped) extent. */
+ if (!shared) {
+ trace_xfs_iomap_found(ip, offset, count, 0, &imap);
+ goto done;
+ }
+
+ /*
+ * Fork all the shared blocks from our write offset until the
+ * end of the extent.
+ */
+ whichfork = XFS_COW_FORK;
+ end_fsb = imap.br_startoff + imap.br_blockcount;
+ } else {
+ /*
+ * We cap the maximum length we map here to MAX_WRITEBACK_PAGES
+ * pages to keep the chunks of work done where somewhat
+ * symmetric with the work writeback does. This is a completely
+ * arbitrary number pulled out of thin air.
+ *
+ * Note that the values needs to be less than 32-bits wide until
+ * the lower level functions are updated.
+ */
+ count = min_t(loff_t, count, 1024 * PAGE_SIZE);
+ end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
}
error = xfs_qm_dqattach_locked(ip, false);
if (error)
goto out_unlock;
- /*
- * We cap the maximum length we map here to MAX_WRITEBACK_PAGES pages
- * to keep the chunks of work done where somewhat symmetric with the
- * work writeback does. This is a completely arbitrary number pulled
- * out of thin air as a best guess for initial testing.
- *
- * Note that the values needs to be less than 32-bits wide until
- * the lower level functions are updated.
- */
- count = min_t(loff_t, count, 1024 * PAGE_SIZE);
- end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
-
- if (eof) {
+ if (eof && whichfork == XFS_DATA_FORK) {
prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count,
&icur);
if (prealloc_blocks) {
@@ -623,9 +670,11 @@ xfs_file_iomap_begin_delay(
}
retry:
- error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
- end_fsb - offset_fsb, prealloc_blocks, &got, &icur,
- eof);
+ error = xfs_bmapi_reserve_delalloc(ip, whichfork, offset_fsb,
+ end_fsb - offset_fsb, prealloc_blocks,
+ whichfork == XFS_DATA_FORK ? &imap : &cmap,
+ whichfork == XFS_DATA_FORK ? &icur : &ccur,
+ whichfork == XFS_DATA_FORK ? eof : cow_eof);
switch (error) {
case 0:
break;
@@ -647,18 +696,18 @@ xfs_file_iomap_begin_delay(
* them out if the write happens to fail.
*/
iomap->flags |= IOMAP_F_NEW;
- trace_xfs_iomap_alloc(ip, offset, count, 0, &got);
+ trace_xfs_iomap_alloc(ip, offset, count, 0, &imap);
done:
- if (isnullstartblock(got.br_startblock))
- got.br_startblock = DELAYSTARTBLOCK;
+ if (isnullstartblock(imap.br_startblock))
+ imap.br_startblock = DELAYSTARTBLOCK;
- if (!got.br_startblock) {
- error = xfs_alert_fsblock_zero(ip, &got);
+ if (!imap.br_startblock) {
+ error = xfs_alert_fsblock_zero(ip, &imap);
if (error)
goto out_unlock;
}
- xfs_bmbt_to_iomap(ip, iomap, &got);
+ xfs_bmbt_to_iomap(ip, iomap, &imap);
out_unlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 31d7c3e62bbc..6a002f024349 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -234,72 +234,6 @@ xfs_reflink_trim_around_shared(
}
}
-/*
- * Trim the passed in imap to the next shared/unshared extent boundary, and
- * if imap->br_startoff points to a shared extent reserve space for it in the
- * COW fork.
- *
- * Note that imap will always contain the block numbers for the existing blocks
- * in the data fork, as the upper layers need them for read-modify-write
- * operations.
- */
-int
-xfs_reflink_reserve_cow(
- struct xfs_inode *ip,
- struct xfs_bmbt_irec *imap)
-{
- struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
- struct xfs_bmbt_irec got;
- int error = 0;
- bool eof = false;
- struct xfs_iext_cursor icur;
- bool shared;
-
- /*
- * Search the COW fork extent list first. This serves two purposes:
- * first this implement the speculative preallocation using cowextisze,
- * so that we also unshared block adjacent to shared blocks instead
- * of just the shared blocks themselves. Second the lookup in the
- * extent list is generally faster than going out to the shared extent
- * tree.
- */
-
- if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
- eof = true;
- if (!eof && got.br_startoff <= imap->br_startoff) {
- trace_xfs_reflink_cow_found(ip, imap);
- xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
- return 0;
- }
-
- /* Trim the mapping to the nearest shared extent boundary. */
- error = xfs_reflink_trim_around_shared(ip, imap, &shared);
- if (error)
- return error;
-
- /* Not shared? Just report the (potentially capped) extent. */
- if (!shared)
- return 0;
-
- /*
- * Fork all the shared blocks from our write offset until the end of
- * the extent.
- */
- error = xfs_qm_dqattach_locked(ip, false);
- if (error)
- return error;
-
- error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
- imap->br_blockcount, 0, &got, &icur, eof);
- if (error == -ENOSPC || error == -EDQUOT)
- trace_xfs_reflink_cow_enospc(ip, imap);
- if (error)
- return error;
-
- trace_xfs_reflink_cow_alloc(ip, &got);
- return 0;
-}
-
/* Convert part of an unwritten CoW extent to a real one. */
STATIC int
xfs_reflink_convert_cow_extent(
--
2.19.1
