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authorFilipe Manana <fdmanana@suse.com>2019-10-30 12:23:11 +0000
committerDavid Sterba <dsterba@suse.com>2019-11-18 17:51:48 +0100
commit11f2069c113e02971b8db6fda62f9b9cd31a030f (patch)
tree5e24002431d04a3e3250a59fcc28cba80baad3a9
parent6b7faadd985c990324b5b5bd18cc4ba5c395eb65 (diff)
downloadlinux-11f2069c113e02971b8db6fda62f9b9cd31a030f.tar.bz2
Btrfs: send, allow clone operations within the same file
For send we currently skip clone operations when the source and destination files are the same. This is so because clone didn't support this case in its early days, but support for it was added back in May 2013 by commit a96fbc72884fcb ("Btrfs: allow file data clone within a file"). This change adds support for it. Example: $ mkfs.btrfs -f /dev/sdd $ mount /dev/sdd /mnt/sdd $ xfs_io -f -c "pwrite -S 0xab -b 64K 0 64K" /mnt/sdd/foobar $ xfs_io -c "reflink /mnt/sdd/foobar 0 64K 64K" /mnt/sdd/foobar $ btrfs subvolume snapshot -r /mnt/sdd /mnt/sdd/snap $ mkfs.btrfs -f /dev/sde $ mount /dev/sde /mnt/sde $ btrfs send /mnt/sdd/snap | btrfs receive /mnt/sde Without this change file foobar at the destination has a single 128Kb extent: $ filefrag -v /mnt/sde/snap/foobar Filesystem type is: 9123683e File size of /mnt/sde/snap/foobar is 131072 (32 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 31: 0.. 31: 32: last,unknown_loc,delalloc,eof /mnt/sde/snap/foobar: 1 extent found With this we get a single 64Kb extent that is shared at file offsets 0 and 64K, just like in the source filesystem: $ filefrag -v /mnt/sde/snap/foobar Filesystem type is: 9123683e File size of /mnt/sde/snap/foobar is 131072 (32 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 15: 3328.. 3343: 16: shared 1: 16.. 31: 3328.. 3343: 16: 3344: last,shared,eof /mnt/sde/snap/foobar: 2 extents found Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/send.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 27e92594a81b..cbf4909f5cd9 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1248,12 +1248,20 @@ static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_)
*/
if (found->root == bctx->sctx->send_root) {
/*
- * TODO for the moment we don't accept clones from the inode
- * that is currently send. We may change this when
- * BTRFS_IOC_CLONE_RANGE supports cloning from and to the same
- * file.
+ * If the source inode was not yet processed we can't issue a
+ * clone operation, as the source extent does not exist yet at
+ * the destination of the stream.
*/
- if (ino >= bctx->cur_objectid)
+ if (ino > bctx->cur_objectid)
+ return 0;
+ /*
+ * We clone from the inode currently being sent as long as the
+ * source extent is already processed, otherwise we could try
+ * to clone from an extent that does not exist yet at the
+ * destination of the stream.
+ */
+ if (ino == bctx->cur_objectid &&
+ offset >= bctx->sctx->cur_inode_next_write_offset)
return 0;
}