Instead enhance xfs_reflink_find_cow_mapping to properly deal with the
fact that we might not have a COW mapping at the offset, and just
return false in this case.
This avoids code duplication, makes xfs_reflink_find_cow_mapping more
robust, and last but not least halves the number of extent map lookups
needed in COW writeback operations.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_aops.c | 28 ++++++++++++++++------------
fs/xfs/xfs_reflink.c | 42 +++++++++++-------------------------------
fs/xfs/xfs_reflink.h | 3 +--
3 files changed, 28 insertions(+), 45 deletions(-)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index d8ce18b..1933803 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -379,10 +379,13 @@ xfs_map_blocks(
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)
- error = xfs_reflink_find_cow_mapping(ip, offset, imap,
- &need_alloc);
- else {
+ 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);
/*
@@ -712,13 +715,14 @@ xfs_is_cow_io(
struct xfs_inode *ip,
xfs_off_t offset)
{
- bool is_cow;
+ 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_is_cow_pending(ip, offset);
+ is_cow = xfs_reflink_find_cow_mapping(ip, offset, &imap, &need_alloc);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
return is_cow;
@@ -1316,12 +1320,12 @@ __xfs_get_blocks(
end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
- if (create && direct)
- is_cow = xfs_reflink_is_cow_pending(ip, offset);
- if (is_cow)
- error = xfs_reflink_find_cow_mapping(ip, offset, &imap,
- &need_alloc);
- else {
+ if (create && direct) {
+ is_cow = xfs_reflink_find_cow_mapping(ip, offset, &imap,
+ &need_alloc);
+ }
+
+ if (!is_cow) {
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
&imap, &nimaps, XFS_BMAPI_ENTIRE);
/*
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 6f87b1e..a1ba7f5 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -429,26 +429,31 @@ advloop:
}
/*
- * Determine if there's a CoW reservation at a byte offset of an inode.
+ * Find the CoW reservation (and whether or not it needs block allocation)
+ * for a given byte offset of a file.
*/
bool
-xfs_reflink_is_cow_pending(
+xfs_reflink_find_cow_mapping(
struct xfs_inode *ip,
- xfs_off_t offset)
+ xfs_off_t offset,
+ struct xfs_bmbt_irec *imap,
+ bool *need_alloc)
{
+ struct xfs_bmbt_irec irec;
struct xfs_ifork *ifp;
struct xfs_bmbt_rec_host *gotp;
- struct xfs_bmbt_irec irec;
xfs_fileoff_t bno;
xfs_extnum_t idx;
+ ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
+
if (!xfs_is_reflink_inode(ip))
return false;
+ /* Find the extent in the CoW fork. */
ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
bno = XFS_B_TO_FSBT(ip->i_mount, offset);
gotp = xfs_iext_bno_to_ext(ifp, bno, &idx);
-
if (!gotp)
return false;
@@ -456,31 +461,6 @@ xfs_reflink_is_cow_pending(
if (bno >= irec.br_startoff + irec.br_blockcount ||
bno < irec.br_startoff)
return false;
- return true;
-}
-
-/*
- * Find the CoW reservation (and whether or not it needs block allocation)
- * for a given byte offset of a file.
- */
-int
-xfs_reflink_find_cow_mapping(
- struct xfs_inode *ip,
- xfs_off_t offset,
- struct xfs_bmbt_irec *imap,
- bool *need_alloc)
-{
- struct xfs_bmbt_irec irec;
- struct xfs_ifork *ifp;
- struct xfs_bmbt_rec_host *gotp;
- xfs_fileoff_t bno;
- xfs_extnum_t idx;
-
- /* Find the extent in the CoW fork. */
- ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
- bno = XFS_B_TO_FSBT(ip->i_mount, offset);
- gotp = xfs_iext_bno_to_ext(ifp, bno, &idx);
- xfs_bmbt_get_all(gotp, &irec);
trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE,
&irec);
@@ -489,7 +469,7 @@ xfs_reflink_find_cow_mapping(
*imap = irec;
*need_alloc = !!(isnullstartblock(irec.br_startblock));
- return 0;
+ return true;
}
/*
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index 398e726..6519f19 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -30,8 +30,7 @@ extern int xfs_reflink_reserve_cow_range(struct xfs_inode *ip,
xfs_fileoff_t offset_fsb, xfs_fileoff_t end_fsb);
extern int xfs_reflink_allocate_cow_range(struct xfs_inode *ip, xfs_off_t pos,
xfs_off_t len);
-extern bool xfs_reflink_is_cow_pending(struct xfs_inode *ip, xfs_off_t offset);
-extern int xfs_reflink_find_cow_mapping(struct xfs_inode *ip, xfs_off_t offset,
+extern bool xfs_reflink_find_cow_mapping(struct xfs_inode *ip, xfs_off_t offset,
struct xfs_bmbt_irec *imap, bool *need_alloc);
extern int xfs_reflink_trim_irec_to_next_cow(struct xfs_inode *ip,
xfs_fileoff_t offset_fsb, struct xfs_bmbt_irec *imap);
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
