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Diffstat (limited to 'fs/xfs/xfs_reflink.c')
-rw-r--r--fs/xfs/xfs_reflink.c265
1 files changed, 185 insertions, 80 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 07593a362cd0..da6d08fb359c 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -82,11 +82,22 @@
* mappings are a reservation against the free space in the filesystem;
* adjacent mappings can also be combined into fewer larger mappings.
*
+ * As an optimization, the CoW extent size hint (cowextsz) creates
+ * outsized aligned delalloc reservations in the hope of landing out of
+ * order nearby CoW writes in a single extent on disk, thereby reducing
+ * fragmentation and improving future performance.
+ *
+ * D: --RRRRRRSSSRRRRRRRR--- (data fork)
+ * C: ------DDDDDDD--------- (CoW fork)
+ *
* When dirty pages are being written out (typically in writepage), the
- * delalloc reservations are converted into real mappings by allocating
- * blocks and replacing the delalloc mapping with real ones. A delalloc
- * mapping can be replaced by several real ones if the free space is
- * fragmented.
+ * delalloc reservations are converted into unwritten mappings by
+ * allocating blocks and replacing the delalloc mapping with real ones.
+ * A delalloc mapping can be replaced by several unwritten ones if the
+ * free space is fragmented.
+ *
+ * D: --RRRRRRSSSRRRRRRRR---
+ * C: ------UUUUUUU---------
*
* We want to adapt the delalloc mechanism for copy-on-write, since the
* write paths are similar. The first two steps (creating the reservation
@@ -101,13 +112,29 @@
* Block-aligned directio writes will use the same mechanism as buffered
* writes.
*
+ * Just prior to submitting the actual disk write requests, we convert
+ * the extents representing the range of the file actually being written
+ * (as opposed to extra pieces created for the cowextsize hint) to real
+ * extents. This will become important in the next step:
+ *
+ * D: --RRRRRRSSSRRRRRRRR---
+ * C: ------UUrrUUU---------
+ *
* CoW remapping must be done after the data block write completes,
* because we don't want to destroy the old data fork map until we're sure
* the new block has been written. Since the new mappings are kept in a
* separate fork, we can simply iterate these mappings to find the ones
* that cover the file blocks that we just CoW'd. For each extent, simply
* unmap the corresponding range in the data fork, map the new range into
- * the data fork, and remove the extent from the CoW fork.
+ * the data fork, and remove the extent from the CoW fork. Because of
+ * the presence of the cowextsize hint, however, we must be careful
+ * only to remap the blocks that we've actually written out -- we must
+ * never remap delalloc reservations nor CoW staging blocks that have
+ * yet to be written. This corresponds exactly to the real extents in
+ * the CoW fork:
+ *
+ * D: --RRRRRRrrSRRRRRRRR---
+ * C: ------UU--UUU---------
*
* Since the remapping operation can be applied to an arbitrary file
* range, we record the need for the remap step as a flag in the ioend
@@ -296,103 +323,165 @@ xfs_reflink_reserve_cow(
return 0;
}
-/* Allocate all CoW reservations covering a range of blocks in a file. */
-static int
-__xfs_reflink_allocate_cow(
- struct xfs_inode *ip,
- xfs_fileoff_t *offset_fsb,
- xfs_fileoff_t end_fsb)
+/* Convert part of an unwritten CoW extent to a real one. */
+STATIC int
+xfs_reflink_convert_cow_extent(
+ struct xfs_inode *ip,
+ struct xfs_bmbt_irec *imap,
+ xfs_fileoff_t offset_fsb,
+ xfs_filblks_t count_fsb,
+ struct xfs_defer_ops *dfops)
{
- struct xfs_mount *mp = ip->i_mount;
- struct xfs_bmbt_irec imap;
- struct xfs_defer_ops dfops;
- struct xfs_trans *tp;
- xfs_fsblock_t first_block;
- int nimaps = 1, error;
- bool shared;
-
- xfs_defer_init(&dfops, &first_block);
+ xfs_fsblock_t first_block;
+ int nimaps = 1;
- error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
- XFS_TRANS_RESERVE, &tp);
- if (error)
- return error;
+ if (imap->br_state == XFS_EXT_NORM)
+ return 0;
- xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trim_extent(imap, offset_fsb, count_fsb);
+ trace_xfs_reflink_convert_cow(ip, imap);
+ if (imap->br_blockcount == 0)
+ return 0;
+ return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount,
+ XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, &first_block,
+ 0, imap, &nimaps, dfops);
+}
- /* Read extent from the source file. */
- nimaps = 1;
- error = xfs_bmapi_read(ip, *offset_fsb, end_fsb - *offset_fsb,
- &imap, &nimaps, 0);
- if (error)
- goto out_unlock;
- ASSERT(nimaps == 1);
+/* Convert all of the unwritten CoW extents in a file's range to real ones. */
+int
+xfs_reflink_convert_cow(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ xfs_off_t count)
+{
+ struct xfs_bmbt_irec got;
+ struct xfs_defer_ops dfops;
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+ xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
+ xfs_extnum_t idx;
+ bool found;
+ int error = 0;
- error = xfs_reflink_reserve_cow(ip, &imap, &shared);
- if (error)
- goto out_trans_cancel;
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
- if (!shared) {
- *offset_fsb = imap.br_startoff + imap.br_blockcount;
- goto out_trans_cancel;
+ /* Convert all the extents to real from unwritten. */
+ for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
+ found && got.br_startoff < end_fsb;
+ found = xfs_iext_get_extent(ifp, ++idx, &got)) {
+ error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
+ end_fsb - offset_fsb, &dfops);
+ if (error)
+ break;
}
- xfs_trans_ijoin(tp, ip, 0);
- error = xfs_bmapi_write(tp, ip, imap.br_startoff, imap.br_blockcount,
- XFS_BMAPI_COWFORK, &first_block,
- XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK),
- &imap, &nimaps, &dfops);
- if (error)
- goto out_trans_cancel;
-
- error = xfs_defer_finish(&tp, &dfops, NULL);
- if (error)
- goto out_trans_cancel;
-
- error = xfs_trans_commit(tp);
-
- *offset_fsb = imap.br_startoff + imap.br_blockcount;
-out_unlock:
+ /* Finish up. */
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
-out_trans_cancel:
- xfs_defer_cancel(&dfops);
- xfs_trans_cancel(tp);
- goto out_unlock;
}
-/* Allocate all CoW reservations covering a part of a file. */
+/* Allocate all CoW reservations covering a range of blocks in a file. */
int
-xfs_reflink_allocate_cow_range(
+xfs_reflink_allocate_cow(
struct xfs_inode *ip,
- xfs_off_t offset,
- xfs_off_t count)
+ struct xfs_bmbt_irec *imap,
+ bool *shared,
+ uint *lockmode)
{
struct xfs_mount *mp = ip->i_mount;
- xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
- xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
- int error;
+ xfs_fileoff_t offset_fsb = imap->br_startoff;
+ xfs_filblks_t count_fsb = imap->br_blockcount;
+ struct xfs_bmbt_irec got;
+ struct xfs_defer_ops dfops;
+ struct xfs_trans *tp = NULL;
+ xfs_fsblock_t first_block;
+ int nimaps, error = 0;
+ bool trimmed;
+ xfs_filblks_t resaligned;
+ xfs_extlen_t resblks = 0;
+ xfs_extnum_t idx;
+retry:
ASSERT(xfs_is_reflink_inode(ip));
-
- trace_xfs_reflink_allocate_cow_range(ip, offset, count);
+ ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
/*
- * Make sure that the dquots are there.
+ * Even if the extent is not shared we might have a preallocation for
+ * it in the COW fork. If so use it.
*/
- error = xfs_qm_dqattach(ip, 0);
- if (error)
- return error;
+ if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &idx, &got) &&
+ got.br_startoff <= offset_fsb) {
+ *shared = true;
- while (offset_fsb < end_fsb) {
- error = __xfs_reflink_allocate_cow(ip, &offset_fsb, end_fsb);
- if (error) {
- trace_xfs_reflink_allocate_cow_range_error(ip, error,
- _RET_IP_);
- break;
+ /* If we have a real allocation in the COW fork we're done. */
+ if (!isnullstartblock(got.br_startblock)) {
+ xfs_trim_extent(&got, offset_fsb, count_fsb);
+ *imap = got;
+ goto convert;
}
+
+ xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
+ } else {
+ error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
+ if (error || !*shared)
+ goto out;
+ }
+
+ if (!tp) {
+ resaligned = xfs_aligned_fsb_count(imap->br_startoff,
+ imap->br_blockcount, xfs_get_cowextsz_hint(ip));
+ resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+
+ xfs_iunlock(ip, *lockmode);
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
+ *lockmode = XFS_ILOCK_EXCL;
+ xfs_ilock(ip, *lockmode);
+
+ if (error)
+ return error;
+
+ error = xfs_qm_dqattach_locked(ip, 0);
+ if (error)
+ goto out;
+ goto retry;
}
+ error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
+ XFS_QMOPT_RES_REGBLKS);
+ if (error)
+ goto out;
+
+ xfs_trans_ijoin(tp, ip, 0);
+
+ xfs_defer_init(&dfops, &first_block);
+ nimaps = 1;
+
+ /* Allocate the entire reservation as unwritten blocks. */
+ error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
+ XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, &first_block,
+ resblks, imap, &nimaps, &dfops);
+ if (error)
+ goto out_bmap_cancel;
+
+ /* Finish up. */
+ error = xfs_defer_finish(&tp, &dfops, NULL);
+ if (error)
+ goto out_bmap_cancel;
+
+ error = xfs_trans_commit(tp);
+ if (error)
+ return error;
+convert:
+ return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb,
+ &dfops);
+out_bmap_cancel:
+ xfs_defer_cancel(&dfops);
+ xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
+ XFS_QMOPT_RES_REGBLKS);
+out:
+ if (tp)
+ xfs_trans_cancel(tp);
return error;
}
@@ -641,6 +730,16 @@ xfs_reflink_end_cow(
ASSERT(!isnullstartblock(got.br_startblock));
+ /*
+ * Don't remap unwritten extents; these are
+ * speculatively preallocated CoW extents that have been
+ * allocated but have not yet been involved in a write.
+ */
+ if (got.br_state == XFS_EXT_UNWRITTEN) {
+ idx--;
+ goto next_extent;
+ }
+
/* Unmap the old blocks in the data fork. */
xfs_defer_init(&dfops, &firstfsb);
rlen = del.br_blockcount;
@@ -855,13 +954,14 @@ STATIC int
xfs_reflink_update_dest(
struct xfs_inode *dest,
xfs_off_t newlen,
- xfs_extlen_t cowextsize)
+ xfs_extlen_t cowextsize,
+ bool is_dedupe)
{
struct xfs_mount *mp = dest->i_mount;
struct xfs_trans *tp;
int error;
- if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
+ if (is_dedupe && newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
return 0;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
@@ -882,6 +982,10 @@ xfs_reflink_update_dest(
dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
}
+ if (!is_dedupe) {
+ xfs_trans_ichgtime(tp, dest,
+ XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+ }
xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
error = xfs_trans_commit(tp);
@@ -1195,7 +1299,8 @@ xfs_reflink_remap_range(
!(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
cowextsize = src->i_d.di_cowextsize;
- ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize);
+ ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
+ is_dedupe);
out_unlock:
xfs_iunlock(src, XFS_MMAPLOCK_EXCL);