[PATCH 4.9 25/72] xfs: only reclaim unwritten COW extents periodically

Greg Kroah-Hartman
2017-04-06T09:25:54Z

From: Christoph Hellwig <hch@lst.de>

commit 3802a345321a08093ba2ddb1849e736f84e8d450 upstream.

We only want to reclaim preallocations from our periodic work item.
Currently this is archived by looking for a dirty inode, but that check
is rather fragile. Instead add a flag to xfs_reflink_cancel_cow_* so
that the caller can ask for just cancelling unwritten extents in the COW
fork.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: fix typos in commit message]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/xfs_aops.c | 2 +-
fs/xfs/xfs_icache.c | 2 +-
fs/xfs/xfs_inode.c | 2 +-
fs/xfs/xfs_reflink.c | 23 ++++++++++++++++-------
fs/xfs/xfs_reflink.h | 4 ++--
fs/xfs/xfs_super.c | 2 +-
6 files changed, 22 insertions(+), 13 deletions(-)

--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -298,7 +298,7 @@ xfs_end_io(
goto done;
if (ioend->io_bio->bi_error) {
error = xfs_reflink_cancel_cow_range(ip,
- ioend->io_offset, ioend->io_size);
+ ioend->io_offset, ioend->io_size, true);
goto done;
}
error = xfs_reflink_end_cow(ip, ioend->io_offset,
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1610,7 +1610,7 @@ xfs_inode_free_cowblocks(
xfs_ilock(ip, XFS_IOLOCK_EXCL);
xfs_ilock(ip, XFS_MMAPLOCK_EXCL);

- ret = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF);
+ ret = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, false);

xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
xfs_iunlock(ip, XFS_IOLOCK_EXCL);
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1624,7 +1624,7 @@ xfs_itruncate_extents(

/* Remove all pending CoW reservations. */
error = xfs_reflink_cancel_cow_blocks(ip, &tp, first_unmap_block,
- last_block);
+ last_block, true);
if (error)
goto out;

--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -571,14 +571,18 @@ xfs_reflink_trim_irec_to_next_cow(
}

/*
- * Cancel all pending CoW reservations for some block range of an inode.
+ * Cancel CoW reservations for some block range of an inode.
+ *
+ * If cancel_real is true this function cancels all COW fork extents for the
+ * inode; if cancel_real is false, real extents are not cleared.
*/
int
xfs_reflink_cancel_cow_blocks(
struct xfs_inode *ip,
struct xfs_trans **tpp,
xfs_fileoff_t offset_fsb,
- xfs_fileoff_t end_fsb)
+ xfs_fileoff_t end_fsb,
+ bool cancel_real)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
struct xfs_bmbt_irec got, prev, del;
@@ -605,7 +609,7 @@ xfs_reflink_cancel_cow_blocks(
&idx, &got, &del);
if (error)
break;
- } else {
+ } else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
xfs_trans_ijoin(*tpp, ip, 0);
xfs_defer_init(&dfops, &firstfsb);

@@ -648,13 +652,17 @@ xfs_reflink_cancel_cow_blocks(
}

/*
- * Cancel all pending CoW reservations for some byte range of an inode.
+ * Cancel CoW reservations for some byte range of an inode.
+ *
+ * If cancel_real is true this function cancels all COW fork extents for the
+ * inode; if cancel_real is false, real extents are not cleared.
*/
int
xfs_reflink_cancel_cow_range(
struct xfs_inode *ip,
xfs_off_t offset,
- xfs_off_t count)
+ xfs_off_t count,
+ bool cancel_real)
{
struct xfs_trans *tp;
xfs_fileoff_t offset_fsb;
@@ -680,7 +688,8 @@ xfs_reflink_cancel_cow_range(
xfs_trans_ijoin(tp, ip, 0);

/* Scrape out the old CoW reservations */
- error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb);
+ error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
+ cancel_real);
if (error)
goto out_cancel;

@@ -1686,7 +1695,7 @@ next:
* We didn't find any shared blocks so turn off the reflink flag.
* First, get rid of any leftover CoW mappings.
*/
- error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF);
+ error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF, true);
if (error)
return error;

--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -39,9 +39,9 @@ extern int xfs_reflink_trim_irec_to_next

extern int xfs_reflink_cancel_cow_blocks(struct xfs_inode *ip,
struct xfs_trans **tpp, xfs_fileoff_t offset_fsb,
- xfs_fileoff_t end_fsb);
+ xfs_fileoff_t end_fsb, bool cancel_real);
extern int xfs_reflink_cancel_cow_range(struct xfs_inode *ip, xfs_off_t offset,
- xfs_off_t count);
+ xfs_off_t count, bool cancel_real);
extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t count);
extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -948,7 +948,7 @@ xfs_fs_destroy_inode(
XFS_STATS_INC(ip->i_mount, vn_remove);

if (xfs_is_reflink_inode(ip)) {
- error = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF);
+ error = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true);
if (error && !XFS_FORCED_SHUTDOWN(ip->i_mount))
xfs_warn(ip->i_mount,
"Error %d while evicting CoW blocks for inode %llu.",