[PATCH 4.19 70/77] btrfs: send: fix wrong file path when there is an inode with a pending rmdir

Greg Kroah-Hartman
2021-01-11T13:11:00Z

From: Filipe Manana <fdmanana@suse.com>

commit 0b3f407e6728d990ae1630a02c7b952c21c288d3 upstream.

When doing an incremental send, if we have a new inode that happens to
have the same number that an old directory inode had in the base snapshot
and that old directory has a pending rmdir operation, we end up computing
a wrong path for the new inode, causing the receiver to fail.

Example reproducer:

$ cat test-send-rmdir.sh
#!/bin/bash

DEV=/dev/sdi
MNT=/mnt/sdi

mkfs.btrfs -f $DEV >/dev/null
mount $DEV $MNT

mkdir $MNT/dir
touch $MNT/dir/file1
touch $MNT/dir/file2
touch $MNT/dir/file3

# Filesystem looks like:
#
# . (ino 256)
# |----- dir/ (ino 257)
# |----- file1 (ino 258)
# |----- file2 (ino 259)
# |----- file3 (ino 260)
#

btrfs subvolume snapshot -r $MNT $MNT/snap1
btrfs send -f /tmp/snap1.send $MNT/snap1

# Now remove our directory and all its files.
rm -fr $MNT/dir

# Unmount the filesystem and mount it again. This is to ensure that
# the next inode that is created ends up with the same inode number
# that our directory "dir" had, 257, which is the first free "objectid"
# available after mounting again the filesystem.
umount $MNT
mount $DEV $MNT

# Now create a new file (it could be a directory as well).
touch $MNT/newfile

# Filesystem now looks like:
#
# . (ino 256)
# |----- newfile (ino 257)
#

btrfs subvolume snapshot -r $MNT $MNT/snap2
btrfs send -f /tmp/snap2.send -p $MNT/snap1 $MNT/snap2

# Now unmount the filesystem, create a new one, mount it and try to apply
# both send streams to recreate both snapshots.
umount $DEV

mkfs.btrfs -f $DEV >/dev/null

mount $DEV $MNT

btrfs receive -f /tmp/snap1.send $MNT
btrfs receive -f /tmp/snap2.send $MNT

umount $MNT

When running the test, the receive operation for the incremental stream
fails:

$ ./test-send-rmdir.sh
Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap1'
At subvol /mnt/sdi/snap1
Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap2'
At subvol /mnt/sdi/snap2
At subvol snap1
At snapshot snap2
ERROR: chown o257-9-0 failed: No such file or directory

So fix this by tracking directories that have a pending rmdir by inode
number and generation number, instead of only inode number.

A test case for fstests follows soon.

Reported-by: Massimo B. <massimo.b@gmx.net>
Tested-by: Massimo B. <massimo.b@gmx.net>
Link: https://lore.kernel.org/linux-btrfs/6ae34776e85912960a253a8327068a892998e685.camel@gmx.net/
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/send.c | 49 +++++++++++++++++++++++++++++++------------------
1 file changed, 31 insertions(+), 18 deletions(-)

--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -238,6 +238,7 @@ struct waiting_dir_move {
* after this directory is moved, we can try to rmdir the ino rmdir_ino.
*/
u64 rmdir_ino;
+ u64 rmdir_gen;
bool orphanized;
};

@@ -308,7 +309,7 @@ static int is_waiting_for_move(struct se
static struct waiting_dir_move *
get_waiting_dir_move(struct send_ctx *sctx, u64 ino);

-static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino);
+static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen);

static int need_send_hole(struct send_ctx *sctx)
{
@@ -2304,7 +2305,7 @@ static int get_cur_path(struct send_ctx

fs_path_reset(name);

- if (is_waiting_for_rm(sctx, ino)) {
+ if (is_waiting_for_rm(sctx, ino, gen)) {
ret = gen_unique_name(sctx, ino, gen, name);
if (ret < 0)
goto out;
@@ -2863,8 +2864,8 @@ out:
return ret;
}

-static struct orphan_dir_info *
-add_orphan_dir_info(struct send_ctx *sctx, u64 dir_ino)
+static struct orphan_dir_info *add_orphan_dir_info(struct send_ctx *sctx,
+ u64 dir_ino, u64 dir_gen)
{
struct rb_node **p = &sctx->orphan_dirs.rb_node;
struct rb_node *parent = NULL;
@@ -2873,20 +2874,23 @@ add_orphan_dir_info(struct send_ctx *sct
while (*p) {
parent = *p;
entry = rb_entry(parent, struct orphan_dir_info, node);
- if (dir_ino < entry->ino) {
+ if (dir_ino < entry->ino)
p = &(*p)->rb_left;
- } else if (dir_ino > entry->ino) {
+ else if (dir_ino > entry->ino)
p = &(*p)->rb_right;
- } else {
+ else if (dir_gen < entry->gen)
+ p = &(*p)->rb_left;
+ else if (dir_gen > entry->gen)
+ p = &(*p)->rb_right;
+ else
return entry;
- }
}

odi = kmalloc(sizeof(*odi), GFP_KERNEL);
if (!odi)
return ERR_PTR(-ENOMEM);
odi->ino = dir_ino;
- odi->gen = 0;
+ odi->gen = dir_gen;
odi->last_dir_index_offset = 0;

rb_link_node(&odi->node, parent, p);
@@ -2894,8 +2898,8 @@ add_orphan_dir_info(struct send_ctx *sct
return odi;
}

-static struct orphan_dir_info *
-get_orphan_dir_info(struct send_ctx *sctx, u64 dir_ino)
+static struct orphan_dir_info *get_orphan_dir_info(struct send_ctx *sctx,
+ u64 dir_ino, u64 gen)
{
struct rb_node *n = sctx->orphan_dirs.rb_node;
struct orphan_dir_info *entry;
@@ -2906,15 +2910,19 @@ get_orphan_dir_info(struct send_ctx *sct
n = n->rb_left;
else if (dir_ino > entry->ino)
n = n->rb_right;
+ else if (gen < entry->gen)
+ n = n->rb_left;
+ else if (gen > entry->gen)
+ n = n->rb_right;
else
return entry;
}
return NULL;
}

-static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino)
+static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen)
{
- struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino);
+ struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino, gen);

return odi != NULL;
}
@@ -2959,7 +2967,7 @@ static int can_rmdir(struct send_ctx *sc
key.type = BTRFS_DIR_INDEX_KEY;
key.offset = 0;

- odi = get_orphan_dir_info(sctx, dir);
+ odi = get_orphan_dir_info(sctx, dir, dir_gen);
if (odi)
key.offset = odi->last_dir_index_offset;

@@ -2990,7 +2998,7 @@ static int can_rmdir(struct send_ctx *sc

dm = get_waiting_dir_move(sctx, loc.objectid);
if (dm) {
- odi = add_orphan_dir_info(sctx, dir);
+ odi = add_orphan_dir_info(sctx, dir, dir_gen);
if (IS_ERR(odi)) {
ret = PTR_ERR(odi);
goto out;
@@ -2998,12 +3006,13 @@ static int can_rmdir(struct send_ctx *sc
odi->gen = dir_gen;
odi->last_dir_index_offset = found_key.offset;
dm->rmdir_ino = dir;
+ dm->rmdir_gen = dir_gen;
ret = 0;
goto out;
}

if (loc.objectid > send_progress) {
- odi = add_orphan_dir_info(sctx, dir);
+ odi = add_orphan_dir_info(sctx, dir, dir_gen);
if (IS_ERR(odi)) {
ret = PTR_ERR(odi);
goto out;
@@ -3043,6 +3052,7 @@ static int add_waiting_dir_move(struct s
return -ENOMEM;
dm->ino = ino;
dm->rmdir_ino = 0;
+ dm->rmdir_gen = 0;
dm->orphanized = orphanized;

while (*p) {
@@ -3188,7 +3198,7 @@ static int path_loop(struct send_ctx *sc
while (ino != BTRFS_FIRST_FREE_OBJECTID) {
fs_path_reset(name);

- if (is_waiting_for_rm(sctx, ino))
+ if (is_waiting_for_rm(sctx, ino, gen))
break;
if (is_waiting_for_move(sctx, ino)) {
if (*ancestor_ino == 0)
@@ -3228,6 +3238,7 @@ static int apply_dir_move(struct send_ct
u64 parent_ino, parent_gen;
struct waiting_dir_move *dm = NULL;
u64 rmdir_ino = 0;
+ u64 rmdir_gen;
u64 ancestor;
bool is_orphan;
int ret;
@@ -3242,6 +3253,7 @@ static int apply_dir_move(struct send_ct
dm = get_waiting_dir_move(sctx, pm->ino);
ASSERT(dm);
rmdir_ino = dm->rmdir_ino;
+ rmdir_gen = dm->rmdir_gen;
is_orphan = dm->orphanized;
free_waiting_dir_move(sctx, dm);

@@ -3278,6 +3290,7 @@ static int apply_dir_move(struct send_ct
dm = get_waiting_dir_move(sctx, pm->ino);
ASSERT(dm);
dm->rmdir_ino = rmdir_ino;
+ dm->rmdir_gen = rmdir_gen;
}
goto out;
}
@@ -3296,7 +3309,7 @@ static int apply_dir_move(struct send_ct
struct orphan_dir_info *odi;
u64 gen;

- odi = get_orphan_dir_info(sctx, rmdir_ino);
+ odi = get_orphan_dir_info(sctx, rmdir_ino, rmdir_gen);
if (!odi) {
/* already deleted */
goto finish;