Btrfs: fix a bug of per-file nocow

Users report a bug, the reproducer is:
$ mkfs.btrfs /dev/loop0
$ mount /dev/loop0 /mnt/btrfs/
$ mkdir /mnt/btrfs/dir
$ chattr +C /mnt/btrfs/dir/
$ dd if=/dev/zero of=/mnt/btrfs/dir/foo bs=4K count=10;
$ lsattr /mnt/btrfs/dir/foo
---------------C- /mnt/btrfs/dir/foo
$ filefrag /mnt/btrfs/dir/foo
/mnt/btrfs/dir/foo: 1 extent found    ---> an extent
$ dd if=/dev/zero of=/mnt/btrfs/dir/foo bs=4K count=1 seek=5 conv=notrunc,nocreat; sync
$ filefrag /mnt/btrfs/dir/foo
/mnt/btrfs/dir/foo: 3 extents found   ---> with nocow, btrfs breaks the extent into three parts

The new created file should not only inherit the NODATACOW flag, but also
honor NODATASUM flag, because we must do COW on a file extent with checksum.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e95b1f90a1f6676b73514877db83fc72986df66a..67ed24ae86bbc1c475517d2593eeca72e56880ac 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4818,8 +4818,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
        if (S_ISREG(mode)) {
                if (btrfs_test_opt(root, NODATASUM))
                        BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
-               if (btrfs_test_opt(root, NODATACOW) ||
-                   (BTRFS_I(dir)->flags & BTRFS_INODE_NODATACOW))
+               if (btrfs_test_opt(root, NODATACOW))
                        BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
        }
 

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index d4608ab72b791682803da6761e52335cb367f31e..7624212ae92600fbebc72bb58ba79b4af9a99309 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -141,8 +141,11 @@ void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
                BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
        }
 
-       if (flags & BTRFS_INODE_NODATACOW)
+       if (flags & BTRFS_INODE_NODATACOW) {
                BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
+               if (S_ISREG(inode->i_mode))
+                       BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
+       }
 
        btrfs_update_iflags(inode);
 }