[PATCH 4.4 093/342] Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots
From: Greg Kroah-Hartman
Date: Tue Mar 01 2016 - 20:09:23 EST
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
commit f32e48e925964c4f8ab917850788a87e1cef3bad upstream.
The following call trace is seen when btrfs/031 test is executed in a loop,
[ 158.661848] ------------[ cut here ]------------
[ 158.662634] WARNING: CPU: 2 PID: 890 at /home/chandan/repos/linux/fs/btrfs/ioctl.c:558 create_subvol+0x3d1/0x6ea()
[ 158.664102] BTRFS: Transaction aborted (error -2)
[ 158.664774] Modules linked in:
[ 158.665266] CPU: 2 PID: 890 Comm: btrfs Not tainted 4.4.0-rc6-g511711a #2
[ 158.666251] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[ 158.667392] ffffffff81c0a6b0 ffff8806c7c4f8e8 ffffffff81431fc8 ffff8806c7c4f930
[ 158.668515] ffff8806c7c4f920 ffffffff81051aa1 ffff880c85aff000 ffff8800bb44d000
[ 158.669647] ffff8808863b5c98 0000000000000000 00000000fffffffe ffff8806c7c4f980
[ 158.670769] Call Trace:
[ 158.671153] [<ffffffff81431fc8>] dump_stack+0x44/0x5c
[ 158.671884] [<ffffffff81051aa1>] warn_slowpath_common+0x81/0xc0
[ 158.672769] [<ffffffff81051b27>] warn_slowpath_fmt+0x47/0x50
[ 158.673620] [<ffffffff813bc98d>] create_subvol+0x3d1/0x6ea
[ 158.674440] [<ffffffff813777c9>] btrfs_mksubvol.isra.30+0x369/0x520
[ 158.675376] [<ffffffff8108a4aa>] ? percpu_down_read+0x1a/0x50
[ 158.676235] [<ffffffff81377a81>] btrfs_ioctl_snap_create_transid+0x101/0x180
[ 158.677268] [<ffffffff81377b52>] btrfs_ioctl_snap_create+0x52/0x70
[ 158.678183] [<ffffffff8137afb4>] btrfs_ioctl+0x474/0x2f90
[ 158.678975] [<ffffffff81144b8e>] ? vma_merge+0xee/0x300
[ 158.679751] [<ffffffff8115be31>] ? alloc_pages_vma+0x91/0x170
[ 158.680599] [<ffffffff81123f62>] ? lru_cache_add_active_or_unevictable+0x22/0x70
[ 158.681686] [<ffffffff813d99cf>] ? selinux_file_ioctl+0xff/0x1d0
[ 158.682581] [<ffffffff8117b791>] do_vfs_ioctl+0x2c1/0x490
[ 158.683399] [<ffffffff813d3cde>] ? security_file_ioctl+0x3e/0x60
[ 158.684297] [<ffffffff8117b9d4>] SyS_ioctl+0x74/0x80
[ 158.685051] [<ffffffff819b2bd7>] entry_SYSCALL_64_fastpath+0x12/0x6a
[ 158.685958] ---[ end trace 4b63312de5a2cb76 ]---
[ 158.686647] BTRFS: error (device loop0) in create_subvol:558: errno=-2 No such entry
[ 158.709508] BTRFS info (device loop0): forced readonly
[ 158.737113] BTRFS info (device loop0): disk space caching is enabled
[ 158.738096] BTRFS error (device loop0): Remounting read-write after error is not allowed
[ 158.851303] BTRFS error (device loop0): cleaner transaction attach returned -30
This occurs because,
Mount filesystem
Create subvol with ID 257
Unmount filesystem
Mount filesystem
Delete subvol with ID 257
btrfs_drop_snapshot()
Add root corresponding to subvol 257 into
btrfs_transaction->dropped_roots list
Create new subvol (i.e. create_subvol())
257 is returned as the next free objectid
btrfs_read_fs_root_no_name()
Finds the btrfs_root instance corresponding to the old subvol with ID 257
in btrfs_fs_info->fs_roots_radix.
Returns error since btrfs_root_item->refs has the value of 0.
To fix the issue the commit initializes tree root's and subvolume root's
highest_objectid when loading the roots from disk.
Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/disk-io.c | 27 +++++++++++++++++++++++++++
fs/btrfs/inode-map.c | 9 +--------
fs/btrfs/inode-map.h | 1 +
fs/btrfs/ioctl.c | 4 ++++
4 files changed, 33 insertions(+), 8 deletions(-)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1582,8 +1582,23 @@ int btrfs_init_fs_root(struct btrfs_root
ret = get_anon_bdev(&root->anon_dev);
if (ret)
goto free_writers;
+
+ mutex_lock(&root->objectid_mutex);
+ ret = btrfs_find_highest_objectid(root,
+ &root->highest_objectid);
+ if (ret) {
+ mutex_unlock(&root->objectid_mutex);
+ goto free_root_dev;
+ }
+
+ ASSERT(root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);
+
+ mutex_unlock(&root->objectid_mutex);
+
return 0;
+free_root_dev:
+ free_anon_bdev(root->anon_dev);
free_writers:
btrfs_free_subvolume_writers(root->subv_writers);
fail:
@@ -2900,6 +2915,18 @@ retry_root_backup:
tree_root->commit_root = btrfs_root_node(tree_root);
btrfs_set_root_refs(&tree_root->root_item, 1);
+ mutex_lock(&tree_root->objectid_mutex);
+ ret = btrfs_find_highest_objectid(tree_root,
+ &tree_root->highest_objectid);
+ if (ret) {
+ mutex_unlock(&tree_root->objectid_mutex);
+ goto recovery_tree_root;
+ }
+
+ ASSERT(tree_root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);
+
+ mutex_unlock(&tree_root->objectid_mutex);
+
ret = btrfs_read_roots(fs_info, tree_root);
if (ret)
goto recovery_tree_root;
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -515,7 +515,7 @@ out:
return ret;
}
-static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
+int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
{
struct btrfs_path *path;
int ret;
@@ -555,13 +555,6 @@ int btrfs_find_free_objectid(struct btrf
int ret;
mutex_lock(&root->objectid_mutex);
- if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
- ret = btrfs_find_highest_objectid(root,
- &root->highest_objectid);
- if (ret)
- goto out;
- }
-
if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
ret = -ENOSPC;
goto out;
--- a/fs/btrfs/inode-map.h
+++ b/fs/btrfs/inode-map.h
@@ -9,5 +9,6 @@ int btrfs_save_ino_cache(struct btrfs_ro
struct btrfs_trans_handle *trans);
int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid);
+int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid);
#endif
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -568,6 +568,10 @@ static noinline int create_subvol(struct
goto fail;
}
+ mutex_lock(&new_root->objectid_mutex);
+ new_root->highest_objectid = new_dirid;
+ mutex_unlock(&new_root->objectid_mutex);
+
/*
* insert the directory item
*/