[PATCH 2/2] Btrfs: fix dedupe vs chattr NODATASUM race
From: Omar Sandoval <osandov@osandov.com>
Date: 2018-05-22 22:02:23
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
From: Omar Sandoval <redacted>
In btrfs_extent_same(), we must check the NODATASUM flag while the
inodes are locked. Otherwise, it's possible that btrfs_ioctl_setflags()
will change the flags after we check. This was correct until a recent
change.
Fixes: 0a38effca37c ("Btrfs: split btrfs_extent_same")
Signed-off-by: Omar Sandoval <redacted>
---
fs/btrfs/ioctl.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 784e267aad32..c2263bf4d6f5 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c@@ -3586,12 +3586,6 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen, if (olen == 0) return 0; - /* don't make the dst file partly checksummed */ - if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) != - (BTRFS_I(dst)->flags & BTRFS_INODE_NODATASUM)) { - return -EINVAL; - } - tail_len = olen % BTRFS_MAX_DEDUPE_LEN; chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN); if (chunk_count == 0)
@@ -3624,6 +3618,13 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen, else btrfs_double_inode_lock(src, dst); + /* don't make the dst file partly checksummed */ + if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) != + (BTRFS_I(dst)->flags & BTRFS_INODE_NODATASUM)) { + ret = -EINVAL; + goto out; + } + for (i = 0; i < chunk_count; i++) { ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN, dst, dst_loff, &cmp);
--
2.17.0