The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 46b2f4590aab71d31088a265c86026b1e96c9de4 Mon Sep 17 00:00:00 2001
From: Filipe Manana fdmanana@suse.com Date: Tue, 24 Jul 2018 11:54:04 +0100 Subject: [PATCH] Btrfs: fix send failure when root has deleted files still open
The more common use case of send involves creating a RO snapshot and then use it for a send operation. In this case it's not possible to have inodes in the snapshot that have a link count of zero (inode with an orphan item) since during snapshot creation we do the orphan cleanup. However, other less common use cases for send can end up seeing inodes with a link count of zero and in this case the send operation fails with a ENOENT error because any attempt to generate a path for the inode, with the purpose of creating it or updating it at the receiver, fails since there are no inode reference items. One use case it to use a regular subvolume for a send operation after turning it to RO mode or turning a RW snapshot into RO mode and then using it for a send operation. In both cases, if a file gets all its hard links deleted while there is an open file descriptor before turning the subvolume/snapshot into RO mode, the send operation will encounter an inode with a link count of zero and then fail with errno ENOENT.
Example using a full send with a subvolume:
$ mkfs.btrfs -f /dev/sdb $ mount /dev/sdb /mnt
$ btrfs subvolume create /mnt/sv1 $ touch /mnt/sv1/foo $ touch /mnt/sv1/bar
# keep an open file descriptor on file bar $ exec 73</mnt/sv1/bar $ unlink /mnt/sv1/bar
# Turn the subvolume to RO mode and use it for a full send, while # holding the open file descriptor. $ btrfs property set /mnt/sv1 ro true
$ btrfs send -f /tmp/full.send /mnt/sv1 At subvol /mnt/sv1 ERROR: send ioctl failed with -2: No such file or directory
Example using an incremental send with snapshots:
$ mkfs.btrfs -f /dev/sdb $ mount /dev/sdb /mnt
$ btrfs subvolume create /mnt/sv1 $ touch /mnt/sv1/foo $ touch /mnt/sv1/bar
$ btrfs subvolume snapshot -r /mnt/sv1 /mnt/snap1
$ echo "hello world" >> /mnt/sv1/bar
$ btrfs subvolume snapshot -r /mnt/sv1 /mnt/snap2
# Turn the second snapshot to RW mode and delete file foo while # holding an open file descriptor on it. $ btrfs property set /mnt/snap2 ro false $ exec 73</mnt/snap2/foo $ unlink /mnt/snap2/foo
# Set the second snapshot back to RO mode and do an incremental send. $ btrfs property set /mnt/snap2 ro true
$ btrfs send -f /tmp/inc.send -p /mnt/snap1 /mnt/snap2 At subvol /mnt/snap2 ERROR: send ioctl failed with -2: No such file or directory
So fix this by ignoring inodes with a link count of zero if we are either doing a full send or if they do not exist in the parent snapshot (they are new in the send snapshot), and unlink all paths found in the parent snapshot when doing an incremental send (and ignoring all other inode items, such as xattrs and extents).
A test case for fstests follows soon.
CC: stable@vger.kernel.org # 4.4+ Reported-by: Martin Wilck martin.wilck@suse.com Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 42e04cd3cd95..551294a6c9e2 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -100,6 +100,7 @@ struct send_ctx { u64 cur_inode_rdev; u64 cur_inode_last_extent; u64 cur_inode_next_write_offset; + bool ignore_cur_inode;
u64 send_progress;
@@ -5796,6 +5797,9 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end) int pending_move = 0; int refs_processed = 0;
+ if (sctx->ignore_cur_inode) + return 0; + ret = process_recorded_refs_if_needed(sctx, at_end, &pending_move, &refs_processed); if (ret < 0) @@ -5914,6 +5918,93 @@ static int finish_inode_if_needed(struct send_ctx *sctx, int at_end) return ret; }
+struct parent_paths_ctx { + struct list_head *refs; + struct send_ctx *sctx; +}; + +static int record_parent_ref(int num, u64 dir, int index, struct fs_path *name, + void *ctx) +{ + struct parent_paths_ctx *ppctx = ctx; + + return record_ref(ppctx->sctx->parent_root, dir, name, ppctx->sctx, + ppctx->refs); +} + +/* + * Issue unlink operations for all paths of the current inode found in the + * parent snapshot. + */ +static int btrfs_unlink_all_paths(struct send_ctx *sctx) +{ + LIST_HEAD(deleted_refs); + struct btrfs_path *path; + struct btrfs_key key; + struct parent_paths_ctx ctx; + int ret; + + path = alloc_path_for_send(); + if (!path) + return -ENOMEM; + + key.objectid = sctx->cur_ino; + key.type = BTRFS_INODE_REF_KEY; + key.offset = 0; + ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0); + if (ret < 0) + goto out; + + ctx.refs = &deleted_refs; + ctx.sctx = sctx; + + while (true) { + struct extent_buffer *eb = path->nodes[0]; + int slot = path->slots[0]; + + if (slot >= btrfs_header_nritems(eb)) { + ret = btrfs_next_leaf(sctx->parent_root, path); + if (ret < 0) + goto out; + else if (ret > 0) + break; + continue; + } + + btrfs_item_key_to_cpu(eb, &key, slot); + if (key.objectid != sctx->cur_ino) + break; + if (key.type != BTRFS_INODE_REF_KEY && + key.type != BTRFS_INODE_EXTREF_KEY) + break; + + ret = iterate_inode_ref(sctx->parent_root, path, &key, 1, + record_parent_ref, &ctx); + if (ret < 0) + goto out; + + path->slots[0]++; + } + + while (!list_empty(&deleted_refs)) { + struct recorded_ref *ref; + + ref = list_first_entry(&deleted_refs, struct recorded_ref, list); + ret = send_unlink(sctx, ref->full_path); + if (ret < 0) + goto out; + fs_path_free(ref->full_path); + list_del(&ref->list); + kfree(ref); + } + ret = 0; +out: + btrfs_free_path(path); + if (ret) + __free_recorded_refs(&deleted_refs); + return ret; +} + static int changed_inode(struct send_ctx *sctx, enum btrfs_compare_tree_result result) { @@ -5928,6 +6019,7 @@ static int changed_inode(struct send_ctx *sctx, sctx->cur_inode_new_gen = 0; sctx->cur_inode_last_extent = (u64)-1; sctx->cur_inode_next_write_offset = 0; + sctx->ignore_cur_inode = false;
/* * Set send_progress to current inode. This will tell all get_cur_xxx @@ -5968,6 +6060,33 @@ static int changed_inode(struct send_ctx *sctx, sctx->cur_inode_new_gen = 1; }
+ /* + * Normally we do not find inodes with a link count of zero (orphans) + * because the most common case is to create a snapshot and use it + * for a send operation. However other less common use cases involve + * using a subvolume and send it after turning it to RO mode just + * after deleting all hard links of a file while holding an open + * file descriptor against it or turning a RO snapshot into RW mode, + * keep an open file descriptor against a file, delete it and then + * turn the snapshot back to RO mode before using it for a send + * operation. So if we find such cases, ignore the inode and all its + * items completely if it's a new inode, or if it's a changed inode + * make sure all its previous paths (from the parent snapshot) are all + * unlinked and all other the inode items are ignored. + */ + if (result == BTRFS_COMPARE_TREE_NEW || + result == BTRFS_COMPARE_TREE_CHANGED) { + u32 nlinks; + + nlinks = btrfs_inode_nlink(sctx->left_path->nodes[0], left_ii); + if (nlinks == 0) { + sctx->ignore_cur_inode = true; + if (result == BTRFS_COMPARE_TREE_CHANGED) + ret = btrfs_unlink_all_paths(sctx); + goto out; + } + } + if (result == BTRFS_COMPARE_TREE_NEW) { sctx->cur_inode_gen = left_gen; sctx->cur_inode_new = 1; @@ -6306,15 +6425,17 @@ static int changed_cb(struct btrfs_path *left_path, key->objectid == BTRFS_FREE_SPACE_OBJECTID) goto out;
- if (key->type == BTRFS_INODE_ITEM_KEY) + if (key->type == BTRFS_INODE_ITEM_KEY) { ret = changed_inode(sctx, result); - else if (key->type == BTRFS_INODE_REF_KEY || - key->type == BTRFS_INODE_EXTREF_KEY) - ret = changed_ref(sctx, result); - else if (key->type == BTRFS_XATTR_ITEM_KEY) - ret = changed_xattr(sctx, result); - else if (key->type == BTRFS_EXTENT_DATA_KEY) - ret = changed_extent(sctx, result); + } else if (!sctx->ignore_cur_inode) { + if (key->type == BTRFS_INODE_REF_KEY || + key->type == BTRFS_INODE_EXTREF_KEY) + ret = changed_ref(sctx, result); + else if (key->type == BTRFS_XATTR_ITEM_KEY) + ret = changed_xattr(sctx, result); + else if (key->type == BTRFS_EXTENT_DATA_KEY) + ret = changed_extent(sctx, result); + }
out: return ret;