Add a new xfs_map_cow helper that does a single consistent lookup in the
COW fork extent map, and remove the existing COW handling code from
xfs_map_blocks.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_aops.c | 119 +++++++++++++++++++++++++++++++-----------------------
1 file changed, 69 insertions(+), 50 deletions(-)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 1933803..2a3f4c1 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -357,15 +357,11 @@ xfs_map_blocks(
int error = 0;
int bmapi_flags = XFS_BMAPI_ENTIRE;
int nimaps = 1;
- int whichfork;
- bool need_alloc;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
- whichfork = (type == XFS_IO_COW ? XFS_COW_FORK : XFS_DATA_FORK);
- need_alloc = (type == XFS_IO_DELALLOC);
-
+ ASSERT(type != XFS_IO_COW);
if (type == XFS_IO_UNWRITTEN)
bmapi_flags |= XFS_BMAPI_IGSTATE;
@@ -378,36 +374,26 @@ xfs_map_blocks(
count = mp->m_super->s_maxbytes - offset;
end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
-
- if (type == XFS_IO_COW) {
- if (!xfs_reflink_find_cow_mapping(ip, offset, imap,
- &need_alloc)) {
- WARN_ON_ONCE(1);
- return -EIO;
- }
- } else {
- 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);
- }
+ 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)
return error;
- if (need_alloc &&
+ if (type == XFS_IO_DELALLOC &&
(!nimaps || isnullstartblock(imap->br_startblock))) {
- error = xfs_iomap_write_allocate(ip, whichfork, offset,
+ 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;
}
@@ -707,27 +693,6 @@ xfs_check_page_type(
return false;
}
-/*
- * Figure out if CoW is pending at this offset.
- */
-static bool
-xfs_is_cow_io(
- struct xfs_inode *ip,
- xfs_off_t offset)
-{
- struct xfs_bmbt_irec imap;
- bool is_cow, need_alloc;
-
- if (!xfs_sb_version_hasreflink(&ip->i_mount->m_sb))
- return false;
-
- xfs_ilock(ip, XFS_ILOCK_SHARED);
- is_cow = xfs_reflink_find_cow_mapping(ip, offset, &imap, &need_alloc);
- xfs_iunlock(ip, XFS_ILOCK_SHARED);
-
- return is_cow;
-}
-
STATIC void
xfs_vm_invalidatepage(
struct page *page,
@@ -804,6 +769,56 @@ 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
@@ -876,8 +891,12 @@ xfs_writepage_map(
continue;
}
- if (xfs_is_cow_io(XFS_I(inode), offset))
- new_type = XFS_IO_COW;
+ if (xfs_sb_version_hasreflink(&XFS_I(inode)->i_mount->m_sb)) {
+ 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;
--
2.1.4
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