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authorDarrick J. Wong <darrick.wong@oracle.com>2016-10-03 09:11:34 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2016-10-04 18:06:41 -0700
commitef4736678fc3ea426968bc82f907798ed5f51e85 (patch)
tree8a1525ef991d72cf833030e0ff081a91f27cbeed /fs/xfs/xfs_aops.c
parent60b4984fc3924bff292ec46b95a3e98b34b8e259 (diff)
xfs: allocate delayed extents in CoW fork
Modify the writepage handler to find and convert pending delalloc extents to real allocations. Furthermore, when we're doing non-cow writes to a part of a file that already has a CoW reservation (the cowextsz hint that we set up in a subsequent patch facilitates this), promote the write to copy-on-write so that the entire extent can get written out as a single extent on disk, thereby reducing post-CoW fragmentation. Christoph moved the CoW support code in _map_blocks to a separate helper function, refactored other functions, and reduced the number of CoW fork lookups, so I merged those changes here to reduce churn. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs/xfs_aops.c')
-rw-r--r--fs/xfs/xfs_aops.c97
1 files changed, 79 insertions, 18 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 007a520b5ddc..c76d7a603338 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -31,6 +31,7 @@
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_bmap_btree.h"
+#include "xfs_reflink.h"
#include <linux/gfp.h>
#include <linux/mpage.h>
#include <linux/pagevec.h>
@@ -341,6 +342,7 @@ xfs_map_blocks(
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
+ ASSERT(type != XFS_IO_COW);
if (type == XFS_IO_UNWRITTEN)
bmapi_flags |= XFS_BMAPI_IGSTATE;
@@ -355,6 +357,13 @@ xfs_map_blocks(
offset_fsb = XFS_B_TO_FSBT(mp, offset);
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
imap, &nimaps, bmapi_flags);
+ /*
+ * Truncate an overwrite extent if there's a pending CoW
+ * reservation before the end of this extent. This forces us
+ * to come back to writepage to take care of the CoW.
+ */
+ if (nimaps && type == XFS_IO_OVERWRITE)
+ xfs_reflink_trim_irec_to_next_cow(ip, offset_fsb, imap);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error)
@@ -365,8 +374,7 @@ xfs_map_blocks(
error = xfs_iomap_write_allocate(ip, XFS_DATA_FORK, offset,
imap);
if (!error)
- trace_xfs_map_blocks_alloc(ip, offset, count, type,
- imap);
+ trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);
return error;
}
@@ -739,6 +747,56 @@ out_invalidate:
return;
}
+static int
+xfs_map_cow(
+ struct xfs_writepage_ctx *wpc,
+ struct inode *inode,
+ loff_t offset,
+ unsigned int *new_type)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_bmbt_irec imap;
+ bool is_cow = false, need_alloc = false;
+ int error;
+
+ /*
+ * If we already have a valid COW mapping keep using it.
+ */
+ if (wpc->io_type == XFS_IO_COW) {
+ wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap, offset);
+ if (wpc->imap_valid) {
+ *new_type = XFS_IO_COW;
+ return 0;
+ }
+ }
+
+ /*
+ * Else we need to check if there is a COW mapping at this offset.
+ */
+ xfs_ilock(ip, XFS_ILOCK_SHARED);
+ is_cow = xfs_reflink_find_cow_mapping(ip, offset, &imap, &need_alloc);
+ xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+ if (!is_cow)
+ return 0;
+
+ /*
+ * And if the COW mapping has a delayed extent here we need to
+ * allocate real space for it now.
+ */
+ if (need_alloc) {
+ error = xfs_iomap_write_allocate(ip, XFS_COW_FORK, offset,
+ &imap);
+ if (error)
+ return error;
+ }
+
+ wpc->io_type = *new_type = XFS_IO_COW;
+ wpc->imap_valid = true;
+ wpc->imap = imap;
+ return 0;
+}
+
/*
* We implement an immediate ioend submission policy here to avoid needing to
* chain multiple ioends and hence nest mempool allocations which can violate
@@ -771,6 +829,7 @@ xfs_writepage_map(
int error = 0;
int count = 0;
int uptodate = 1;
+ unsigned int new_type;
bh = head = page_buffers(page);
offset = page_offset(page);
@@ -791,22 +850,13 @@ xfs_writepage_map(
continue;
}
- if (buffer_unwritten(bh)) {
- if (wpc->io_type != XFS_IO_UNWRITTEN) {
- wpc->io_type = XFS_IO_UNWRITTEN;
- wpc->imap_valid = false;
- }
- } else if (buffer_delay(bh)) {
- if (wpc->io_type != XFS_IO_DELALLOC) {
- wpc->io_type = XFS_IO_DELALLOC;
- wpc->imap_valid = false;
- }
- } else if (buffer_uptodate(bh)) {
- if (wpc->io_type != XFS_IO_OVERWRITE) {
- wpc->io_type = XFS_IO_OVERWRITE;
- wpc->imap_valid = false;
- }
- } else {
+ if (buffer_unwritten(bh))
+ new_type = XFS_IO_UNWRITTEN;
+ else if (buffer_delay(bh))
+ new_type = XFS_IO_DELALLOC;
+ else if (buffer_uptodate(bh))
+ new_type = XFS_IO_OVERWRITE;
+ else {
if (PageUptodate(page))
ASSERT(buffer_mapped(bh));
/*
@@ -819,6 +869,17 @@ xfs_writepage_map(
continue;
}
+ if (xfs_is_reflink_inode(XFS_I(inode))) {
+ error = xfs_map_cow(wpc, inode, offset, &new_type);
+ if (error)
+ goto out;
+ }
+
+ if (wpc->io_type != new_type) {
+ wpc->io_type = new_type;
+ wpc->imap_valid = false;
+ }
+
if (wpc->imap_valid)
wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap,
offset);