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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-17 11:21:05 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-17 11:21:05 -0800 |
commit | effaf90137e3a9bb9702746f993f369a53c4185f (patch) | |
tree | 8fdf11b4e9bfbcf159b6f73928fa2782c04b433c /fs/btrfs/relocation.c | |
parent | ab7541c3addd344939e76d0636da0048ce24f2db (diff) | |
parent | b35cf1f0bf1f2b0b193093338414b9bd63b29015 (diff) | |
download | linux-effaf90137e3a9bb9702746f993f369a53c4185f.tar.bz2 |
Merge tag 'for-5.5-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes that have been in the works during last twp weeks.
All have a user visible effect and are stable material:
- scrub: properly update progress after calling cancel ioctl, calling
'resume' would start from the beginning otherwise
- fix subvolume reference removal, after moving out of the original
path the reference is not recognized and will lead to transaction
abort
- fix reloc root lifetime checks, could lead to crashes when there's
subvolume cleaning running in parallel
- fix memory leak when quotas get disabled in the middle of extent
accounting
- fix transaction abort in case of balance being started on degraded
mount on eg. RAID1"
* tag 'for-5.5-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: check rw_devices, not num_devices for balance
Btrfs: always copy scrub arguments back to user space
btrfs: relocation: fix reloc_root lifespan and access
btrfs: fix memory leak in qgroup accounting
btrfs: do not delete mismatched root refs
btrfs: fix invalid removal of root ref
btrfs: rework arguments of btrfs_unlink_subvol
Diffstat (limited to 'fs/btrfs/relocation.c')
-rw-r--r-- | fs/btrfs/relocation.c | 51 |
1 files changed, 46 insertions, 5 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index c58245797f30..da5abd62db22 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -517,6 +517,34 @@ static int update_backref_cache(struct btrfs_trans_handle *trans, return 1; } +static bool reloc_root_is_dead(struct btrfs_root *root) +{ + /* + * Pair with set_bit/clear_bit in clean_dirty_subvols and + * btrfs_update_reloc_root. We need to see the updated bit before + * trying to access reloc_root + */ + smp_rmb(); + if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state)) + return true; + return false; +} + +/* + * Check if this subvolume tree has valid reloc tree. + * + * Reloc tree after swap is considered dead, thus not considered as valid. + * This is enough for most callers, as they don't distinguish dead reloc root + * from no reloc root. But should_ignore_root() below is a special case. + */ +static bool have_reloc_root(struct btrfs_root *root) +{ + if (reloc_root_is_dead(root)) + return false; + if (!root->reloc_root) + return false; + return true; +} static int should_ignore_root(struct btrfs_root *root) { @@ -525,6 +553,10 @@ static int should_ignore_root(struct btrfs_root *root) if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state)) return 0; + /* This root has been merged with its reloc tree, we can ignore it */ + if (reloc_root_is_dead(root)) + return 1; + reloc_root = root->reloc_root; if (!reloc_root) return 0; @@ -1439,7 +1471,7 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans, * The subvolume has reloc tree but the swap is finished, no need to * create/update the dead reloc tree */ - if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state)) + if (reloc_root_is_dead(root)) return 0; if (root->reloc_root) { @@ -1478,8 +1510,7 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, struct btrfs_root_item *root_item; int ret; - if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) || - !root->reloc_root) + if (!have_reloc_root(root)) goto out; reloc_root = root->reloc_root; @@ -1489,6 +1520,11 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, if (fs_info->reloc_ctl->merge_reloc_tree && btrfs_root_refs(root_item) == 0) { set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); + /* + * Mark the tree as dead before we change reloc_root so + * have_reloc_root will not touch it from now on. + */ + smp_wmb(); __del_reloc_root(reloc_root); } @@ -2201,6 +2237,11 @@ static int clean_dirty_subvols(struct reloc_control *rc) if (ret2 < 0 && !ret) ret = ret2; } + /* + * Need barrier to ensure clear_bit() only happens after + * root->reloc_root = NULL. Pairs with have_reloc_root. + */ + smp_wmb(); clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); btrfs_put_fs_root(root); } else { @@ -4718,7 +4759,7 @@ void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending, struct btrfs_root *root = pending->root; struct reloc_control *rc = root->fs_info->reloc_ctl; - if (!root->reloc_root || !rc) + if (!rc || !have_reloc_root(root)) return; if (!rc->merge_reloc_tree) @@ -4752,7 +4793,7 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, struct reloc_control *rc = root->fs_info->reloc_ctl; int ret; - if (!root->reloc_root || !rc) + if (!rc || !have_reloc_root(root)) return 0; rc = root->fs_info->reloc_ctl; |