Wire up write_begin and page_mkwrite to detect shared extents and
create delayed allocation extents in the CoW fork.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/xfs_aops.c | 10 ++++
fs/xfs/xfs_file.c | 10 ++++
fs/xfs/xfs_reflink.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_reflink.h | 3 +
4 files changed, 163 insertions(+)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 29e7e5d..afb62e0 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>
@@ -1831,6 +1832,15 @@ xfs_vm_write_begin(
if (!page)
return -ENOMEM;
+ /* Reserve delalloc blocks for CoW. */
+ status = xfs_reflink_reserve_cow_range(XFS_I(mapping->host), pos, len);
+ if (status) {
+ unlock_page(page);
+ page_cache_release(page);
+ *pagep = NULL;
+ return status;
+ }
+
status = __block_write_begin(page, pos, len, xfs_get_blocks);
if (unlikely(status)) {
struct inode *inode = mapping->host;
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index f5392ab..0fbcb38 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -37,6 +37,7 @@
#include "xfs_log.h"
#include "xfs_icache.h"
#include "xfs_pnfs.h"
+#include "xfs_reflink.h"
#include <linux/dcache.h>
#include <linux/falloc.h>
@@ -1518,6 +1519,14 @@ xfs_filemap_page_mkwrite(
file_update_time(vma->vm_file);
xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+ /* Reserve delalloc blocks for CoW. */
+ ret = xfs_reflink_reserve_cow_range(XFS_I(inode),
+ vmf->page->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE);
+ if (ret) {
+ ret = block_page_mkwrite_return(ret);
+ goto out;
+ }
+
if (IS_DAX(inode)) {
ret = __dax_mkwrite(vma, vmf, xfs_get_blocks_dax_fault, NULL);
} else {
@@ -1525,6 +1534,7 @@ xfs_filemap_page_mkwrite(
ret = block_page_mkwrite_return(ret);
}
+out:
xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
sb_end_pagefault(inode->i_sb);
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index bbcd50c..fdc538e 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -48,6 +48,7 @@
#include "xfs_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_reflink.h"
+#include "xfs_iomap.h"
/*
* Copy on Write of Shared Blocks
@@ -109,3 +110,142 @@
* ioend structure. Better yet, the more ground we can cover with one
* ioend, the better.
*/
+
+/* Trim extent to fit a logical block range. */
+static void
+xfs_trim_extent(
+ struct xfs_bmbt_irec *irec,
+ xfs_fileoff_t bno,
+ xfs_extlen_t len)
+{
+ xfs_fileoff_t distance;
+ xfs_fileoff_t end = bno + len;
+
+ if (irec->br_startoff < bno) {
+ distance = bno - irec->br_startoff;
+ irec->br_startblock += distance;
+ irec->br_startoff += distance;
+ irec->br_blockcount -= distance;
+ }
+
+ if (end < irec->br_startoff + irec->br_blockcount) {
+ distance = irec->br_startoff + irec->br_blockcount - end;
+ irec->br_blockcount -= distance;
+ }
+}
+
+/* Find the shared ranges under an irec, and set up delalloc extents. */
+STATIC int
+xfs_reflink_reserve_cow_extent(
+ struct xfs_inode *ip,
+ struct xfs_bmbt_irec *irec)
+{
+ struct xfs_bmbt_irec rec;
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ xfs_extlen_t aglen;
+ xfs_agblock_t fbno;
+ xfs_extlen_t flen;
+ xfs_fileoff_t lblk;
+ xfs_off_t foffset;
+ xfs_extlen_t distance;
+ size_t fsize;
+ int error = 0;
+
+ /* Holes, unwritten, and delalloc extents cannot be shared */
+ if (ISUNWRITTEN(irec) ||
+ irec->br_startblock == HOLESTARTBLOCK ||
+ irec->br_startblock == DELAYSTARTBLOCK)
+ return 0;
+
+ trace_xfs_reflink_reserve_cow_extent(ip, irec);
+ agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock);
+ agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock);
+ lblk = irec->br_startoff;
+ aglen = irec->br_blockcount;
+
+ while (aglen > 0) {
+ /* Find maximal fork range within this extent */
+ error = xfs_refcount_find_shared(ip->i_mount, agno, agbno,
+ aglen, &fbno, &flen, true);
+ if (error)
+ break;
+ if (flen == 0) {
+ distance = fbno - agbno;
+ goto advloop;
+ }
+
+ /* Add as much as we can to the cow fork */
+ foffset = XFS_FSB_TO_B(ip->i_mount, lblk + fbno - agbno);
+ fsize = XFS_FSB_TO_B(ip->i_mount, flen);
+ error = xfs_iomap_cow_delay(ip, foffset, fsize, &rec);
+ if (error)
+ break;
+
+ distance = (rec.br_startoff - lblk) + rec.br_blockcount;
+advloop:
+ if (aglen < distance)
+ break;
+ aglen -= distance;
+ agbno += distance;
+ lblk += distance;
+ }
+
+ if (error)
+ trace_xfs_reflink_reserve_cow_extent_error(ip, error, _RET_IP_);
+ return error;
+}
+
+/**
+ * xfs_reflink_reserve_cow_range() -- Reserve blocks to satisfy a copy on
+ * write operation.
+ * @ip: XFS inode.
+ * @pos: file offset to start CoWing.
+ * @len: number of bytes to CoW.
+ */
+int
+xfs_reflink_reserve_cow_range(
+ struct xfs_inode *ip,
+ xfs_off_t pos,
+ xfs_off_t len)
+{
+ struct xfs_bmbt_irec imap;
+ int nimaps;
+ int error = 0;
+ xfs_fileoff_t lblk;
+ xfs_fileoff_t next_lblk;
+ xfs_off_t offset;
+
+ if (!xfs_is_reflink_inode(ip))
+ return 0;
+
+ trace_xfs_reflink_reserve_cow_range(ip, len, pos, 0);
+
+ lblk = XFS_B_TO_FSBT(ip->i_mount, pos);
+ next_lblk = XFS_B_TO_FSB(ip->i_mount, pos + len - 1);
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ while (lblk < next_lblk) {
+ offset = XFS_FSB_TO_B(ip->i_mount, lblk);
+ /* Read extent from the source file. */
+ nimaps = 1;
+ error = xfs_bmapi_read(ip, lblk, next_lblk - lblk, &imap,
+ &nimaps, 0);
+ if (error)
+ break;
+
+ if (nimaps == 0)
+ break;
+
+ /* Fork all the shared blocks in this extent. */
+ error = xfs_reflink_reserve_cow_extent(ip, &imap);
+ if (error)
+ break;
+
+ lblk += imap.br_blockcount;
+ }
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+ if (error)
+ trace_xfs_reflink_reserve_cow_range_error(ip, error, _RET_IP_);
+ return error;
+}
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index e967cff..41afdbe 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -18,4 +18,7 @@
#ifndef __XFS_REFLINK_H
#define __XFS_REFLINK_H 1
+extern int xfs_reflink_reserve_cow_range(struct xfs_inode *ip, xfs_off_t pos,
+ xfs_off_t len);
+
#endif /* __XFS_REFLINK_H */
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