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authorQu Wenruo <wqu@suse.com>2020-07-13 04:03:21 +0300
committerDavid Sterba <dsterba@suse.com>2020-07-27 13:55:45 +0300
commit44d354abf33e92a5e73b965c84caf5a5d5e58a0b (patch)
treeeb20cf1af6d250616b5aee54e7fdeb600b79d650 /fs
parentf3e3d9cc35252a70a2fd698762c9687718268ec6 (diff)
downloadlinux-44d354abf33e92a5e73b965c84caf5a5d5e58a0b.tar.xz
btrfs: relocation: review the call sites which can be interrupted by signal
Since most metadata reservation calls can return -EINTR when get interrupted by fatal signal, we need to review the all the metadata reservation call sites. In relocation code, the metadata reservation happens in the following sites: - btrfs_block_rsv_refill() in merge_reloc_root() merge_reloc_root() is a pretty critical section, we don't want to be interrupted by signal, so change the flush status to BTRFS_RESERVE_FLUSH_LIMIT, so it won't get interrupted by signal. Since such change can be ENPSPC-prone, also shrink the amount of metadata to reserve least amount avoid deadly ENOSPC there. - btrfs_block_rsv_refill() in reserve_metadata_space() It calls with BTRFS_RESERVE_FLUSH_LIMIT, which won't get interrupted by signal. - btrfs_block_rsv_refill() in prepare_to_relocate() - btrfs_block_rsv_add() in prepare_to_relocate() - btrfs_block_rsv_refill() in relocate_block_group() - btrfs_delalloc_reserve_metadata() in relocate_file_extent_cluster() - btrfs_start_transaction() in relocate_block_group() - btrfs_start_transaction() in create_reloc_inode() Can be interrupted by fatal signal and we can handle it easily. For these call sites, just catch the -EINTR value in btrfs_balance() and count them as canceled. CC: stable@vger.kernel.org # 5.4+ Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/relocation.c12
-rw-r--r--fs/btrfs/volumes.c17
2 files changed, 26 insertions, 3 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 2b869fb2e62c..4ba1ab9cc76d 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1686,12 +1686,20 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
btrfs_unlock_up_safe(path, 0);
}
- min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
+ /*
+ * In merge_reloc_root(), we modify the upper level pointer to swap the
+ * tree blocks between reloc tree and subvolume tree. Thus for tree
+ * block COW, we COW at most from level 1 to root level for each tree.
+ *
+ * Thus the needed metadata size is at most root_level * nodesize,
+ * and * 2 since we have two trees to COW.
+ */
+ min_reserved = fs_info->nodesize * btrfs_root_level(root_item) * 2;
memset(&next_key, 0, sizeof(next_key));
while (1) {
ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
- BTRFS_RESERVE_FLUSH_ALL);
+ BTRFS_RESERVE_FLUSH_LIMIT);
if (ret) {
err = ret;
goto out;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c1a4dab8e811..537ccf66ee20 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4135,7 +4135,22 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
mutex_lock(&fs_info->balance_mutex);
if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req))
btrfs_info(fs_info, "balance: paused");
- else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req))
+ /*
+ * Balance can be canceled by:
+ *
+ * - Regular cancel request
+ * Then ret == -ECANCELED and balance_cancel_req > 0
+ *
+ * - Fatal signal to "btrfs" process
+ * Either the signal caught by wait_reserve_ticket() and callers
+ * got -EINTR, or caught by btrfs_should_cancel_balance() and
+ * got -ECANCELED.
+ * Either way, in this case balance_cancel_req = 0, and
+ * ret == -EINTR or ret == -ECANCELED.
+ *
+ * So here we only check the return value to catch canceled balance.
+ */
+ else if (ret == -ECANCELED || ret == -EINTR)
btrfs_info(fs_info, "balance: canceled");
else
btrfs_info(fs_info, "balance: ended with status: %d", ret);