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authorNaohiro Aota <naohiro.aota@wdc.com>2022-04-18 10:15:03 +0300
committerDavid Sterba <dsterba@suse.com>2022-04-21 17:06:24 +0300
commit5f0addf7b89085f8e0a2593faa419d6111612b9b (patch)
tree905a717629401721cac29243b43bd23f324d122a /fs/btrfs/zoned.h
parenta692e13d87cb6d0193387aac55cfcc947077c20b (diff)
downloadlinux-5f0addf7b89085f8e0a2593faa419d6111612b9b.tar.xz
btrfs: zoned: use dedicated lock for data relocation
Currently, we use btrfs_inode_{lock,unlock}() to grant an exclusive writeback of the relocation data inode in btrfs_zoned_data_reloc_{lock,unlock}(). However, that can cause a deadlock in the following path. Thread A takes btrfs_inode_lock() and waits for metadata reservation by e.g, waiting for writeback: prealloc_file_extent_cluster() - btrfs_inode_lock(&inode->vfs_inode, 0); - btrfs_prealloc_file_range() ... - btrfs_replace_file_extents() - btrfs_start_transaction ... - btrfs_reserve_metadata_bytes() Thread B (e.g, doing a writeback work) needs to wait for the inode lock to continue writeback process: do_writepages - btrfs_writepages - extent_writpages - btrfs_zoned_data_reloc_lock(BTRFS_I(inode)); - btrfs_inode_lock() The deadlock is caused by relying on the vfs_inode's lock. By using it, we introduced unnecessary exclusion of writeback and btrfs_prealloc_file_range(). Also, the lock at this point is useless as we don't have any dirty pages in the inode yet. Introduce fs_info->zoned_data_reloc_io_lock and use it for the exclusive writeback. Fixes: 35156d852762 ("btrfs: zoned: only allow one process to add pages to a relocation inode") CC: stable@vger.kernel.org # 5.16.x: 869f4cdc73f9: btrfs: zoned: encapsulate inode locking for zoned relocation CC: stable@vger.kernel.org # 5.16.x CC: stable@vger.kernel.org # 5.17 Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/zoned.h')
-rw-r--r--fs/btrfs/zoned.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index cbf016a7bb5d..6dee76248cb4 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -359,7 +359,7 @@ static inline void btrfs_zoned_data_reloc_lock(struct btrfs_inode *inode)
struct btrfs_root *root = inode->root;
if (btrfs_is_data_reloc_root(root) && btrfs_is_zoned(root->fs_info))
- btrfs_inode_lock(&inode->vfs_inode, 0);
+ mutex_lock(&root->fs_info->zoned_data_reloc_io_lock);
}
static inline void btrfs_zoned_data_reloc_unlock(struct btrfs_inode *inode)
@@ -367,7 +367,7 @@ static inline void btrfs_zoned_data_reloc_unlock(struct btrfs_inode *inode)
struct btrfs_root *root = inode->root;
if (btrfs_is_data_reloc_root(root) && btrfs_is_zoned(root->fs_info))
- btrfs_inode_unlock(&inode->vfs_inode, 0);
+ mutex_unlock(&root->fs_info->zoned_data_reloc_io_lock);
}
#endif