From f32e48e925964c4f8ab917850788a87e1cef3bad Mon Sep 17 00:00:00 2001 From: Chandan Rajendra Date: Thu, 7 Jan 2016 18:56:59 +0530 Subject: [PATCH] Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 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] [] dump_stack+0x44/0x5c [ 158.671884] [] warn_slowpath_common+0x81/0xc0 [ 158.672769] [] warn_slowpath_fmt+0x47/0x50 [ 158.673620] [] create_subvol+0x3d1/0x6ea [ 158.674440] [] btrfs_mksubvol.isra.30+0x369/0x520 [ 158.675376] [] ? percpu_down_read+0x1a/0x50 [ 158.676235] [] btrfs_ioctl_snap_create_transid+0x101/0x180 [ 158.677268] [] btrfs_ioctl_snap_create+0x52/0x70 [ 158.678183] [] btrfs_ioctl+0x474/0x2f90 [ 158.678975] [] ? vma_merge+0xee/0x300 [ 158.679751] [] ? alloc_pages_vma+0x91/0x170 [ 158.680599] [] ? lru_cache_add_active_or_unevictable+0x22/0x70 [ 158.681686] [] ? selinux_file_ioctl+0xff/0x1d0 [ 158.682581] [] do_vfs_ioctl+0x2c1/0x490 [ 158.683399] [] ? security_file_ioctl+0x3e/0x60 [ 158.684297] [] SyS_ioctl+0x74/0x80 [ 158.685051] [] 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 Signed-off-by: David Sterba --- 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(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 216f97765b565..868736dbe6ee0 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1582,8 +1582,23 @@ int btrfs_init_fs_root(struct btrfs_root *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: @@ -2901,6 +2916,18 @@ 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; diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c index 1951ad69382fb..29e23a57d6f36 100644 --- 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 btrfs_root *root, u64 *objectid) 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; diff --git a/fs/btrfs/inode-map.h b/fs/btrfs/inode-map.h index ddb347bfee232..c8e864b2d530f 100644 --- a/fs/btrfs/inode-map.h +++ b/fs/btrfs/inode-map.h @@ -9,5 +9,6 @@ int btrfs_save_ino_cache(struct btrfs_root *root, 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 diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 3d9b27d2176e7..b20463b993a65 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -568,6 +568,10 @@ static noinline int create_subvol(struct inode *dir, goto fail; } + mutex_lock(&new_root->objectid_mutex); + new_root->highest_objectid = new_dirid; + mutex_unlock(&new_root->objectid_mutex); + /* * insert the directory item */