From 2c307174ab77e34645e75e12827646e044d273c3 Mon Sep 17 00:00:00 2001
From: Dave Chinner <dchinner@redhat.com>
Date: Mon, 19 Nov 2018 13:31:10 -0800
Subject: [PATCH] xfs: flush removing page cache in xfs_reflink_remap_prep
Git-commit: 2c307174ab77e34645e75e12827646e044d273c3
Patch-mainline: v4.20-rc4
References: bsc#1132414, bsc#1132219
On a sub-page block size filesystem, fsx is failing with a data
corruption after a series of operations involving copying a file
with the destination offset beyond EOF of the destination of the file:
8093(157 mod 256): TRUNCATE DOWN from 0x7a120 to 0x50000 ******WWWW
8094(158 mod 256): INSERT 0x25000 thru 0x25fff (0x1000 bytes)
8095(159 mod 256): COPY 0x18000 thru 0x1afff (0x3000 bytes) to 0x2f400
8096(160 mod 256): WRITE 0x5da00 thru 0x651ff (0x7800 bytes) HOLE
8097(161 mod 256): COPY 0x2000 thru 0x5fff (0x4000 bytes) to 0x6fc00
The second copy here is beyond EOF, and it is to sub-page (4k) but
block aligned (1k) offset. The clone runs the EOF zeroing, landing
in a pre-existing post-eof delalloc extent. This zeroes the post-eof
extents in the page cache just fine, dirtying the pages correctly.
The problem is that xfs_reflink_remap_prep() now truncates the page
cache over the range that it is copying it to, and rounds that down
to cover the entire start page. This removes the dirty page over the
delalloc extent from the page cache without having written it back.
Hence later, when the page cache is flushed, the page at offset
0x6f000 has not been written back and hence exposes stale data,
which fsx trips over less than 10 operations later.
Fix this by changing xfs_reflink_remap_prep() to use
xfs_flush_unmap_range().
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Anthony Iliopoulos <ailiopoulos@suse.com>
---
fs/xfs/xfs_bmap_util.c | 2 +-
fs/xfs/xfs_bmap_util.h | 3 +++
fs/xfs/xfs_reflink.c | 17 +++++++++++++----
3 files changed, 17 insertions(+), 5 deletions(-)
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1112,7 +1112,7 @@
return 0;
}
-static int
+int
xfs_flush_unmap_range(
struct xfs_inode *ip,
xfs_off_t offset,
--- a/fs/xfs/xfs_bmap_util.h
+++ b/fs/xfs/xfs_bmap_util.h
@@ -87,4 +87,7 @@
xfs_daddr_t xfs_fsb_to_db(struct xfs_inode *ip, xfs_fsblock_t fsb);
xfs_extnum_t xfs_bmap_count_leaves(struct xfs_ifork *ifp, xfs_filblks_t *count);
+
+int xfs_flush_unmap_range(struct xfs_inode *ip, xfs_off_t offset,
+ xfs_off_t len);
#endif /* __XFS_BMAP_UTIL_H__ */
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1436,10 +1436,19 @@
if (ret)
goto out_unlock;
- /* Zap any page cache for the destination file's range. */
- truncate_inode_pages_range(&inode_out->i_data,
- round_down(pos_out, PAGE_SIZE),
- round_up(pos_out + *len, PAGE_SIZE) - 1);
+ /*
+ * If pos_out > EOF, we may have dirtied blocks between EOF and
+ * pos_out. In that case, we need to extend the flush and unmap to cover
+ * from EOF to the end of the copy length.
+ */
+ if (pos_out > XFS_ISIZE(dest)) {
+ loff_t flen = *len + (pos_out - XFS_ISIZE(dest));
+ ret = xfs_flush_unmap_range(dest, XFS_ISIZE(dest), flen);
+ } else {
+ ret = xfs_flush_unmap_range(dest, pos_out, *len);
+ }
+ if (ret)
+ goto out_unlock;
/* If we're altering the file contents... */
if (!is_dedupe) {