Re: [PATCH v2 1/4] btrfs: zoned: encapsulate inode locking for zoned relocation

[David Sterba <dsterba@suse.cz>]

On Tue, Dec 07, 2021 at 06:28:34AM -0800, Johannes Thumshirn wrote:
> Encapsulate the inode lock needed for serializing the data relocation
> writes on a zoned filesystem into a helper.
> 
> This streamlines the code reading flow and hides special casing for
> zoned filesystems.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/extent_io.c |  8 ++------
>  fs/btrfs/zoned.h     | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 1a67f4b3986b..cc27e6e6d6ce 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -5184,8 +5184,6 @@ int extent_writepages(struct address_space *mapping,
>  		      struct writeback_control *wbc)
>  {
>  	struct inode *inode = mapping->host;
> -	const bool data_reloc = btrfs_is_data_reloc_root(BTRFS_I(inode)->root);
> -	const bool zoned = btrfs_is_zoned(BTRFS_I(inode)->root->fs_info);
>  	int ret = 0;
>  	struct extent_page_data epd = {
>  		.bio_ctrl = { 0 },
> @@ -5197,11 +5195,9 @@ int extent_writepages(struct address_space *mapping,
>  	 * Allow only a single thread to do the reloc work in zoned mode to
>  	 * protect the write pointer updates.
>  	 */
> -	if (data_reloc && zoned)
> -		btrfs_inode_lock(inode, 0);
> +	btrfs_zoned_data_reloc_lock(inode);
>  	ret = extent_write_cache_pages(mapping, wbc, &epd);
> -	if (data_reloc && zoned)
> -		btrfs_inode_unlock(inode, 0);
> +	btrfs_zoned_data_reloc_unlock(inode);
>  	ASSERT(ret <= 0);
>  	if (ret < 0) {
>  		end_write_bio(&epd, ret);
> diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
> index 4344f4818389..e3eaf03a3422 100644
> --- a/fs/btrfs/zoned.h
> +++ b/fs/btrfs/zoned.h
> @@ -8,6 +8,7 @@
>  #include "volumes.h"
>  #include "disk-io.h"
>  #include "block-group.h"
> +#include "btrfs_inode.h"
>  
>  /*
>   * Block groups with more than this value (percents) of unusable space will be
> @@ -354,4 +355,20 @@ static inline void btrfs_clear_treelog_bg(struct btrfs_block_group *bg)
>  	spin_unlock(&fs_info->treelog_bg_lock);
>  }
>  
> +static inline void btrfs_zoned_data_reloc_lock(struct inode *inode)

All internal API should use struct btrfs_inode, applied with the
following diff:

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5195,9 +5195,9 @@ int extent_writepages(struct address_space *mapping,
         * Allow only a single thread to do the reloc work in zoned mode to
         * protect the write pointer updates.
         */
-       btrfs_zoned_data_reloc_lock(inode);
+       btrfs_zoned_data_reloc_lock(BTRFS_I(inode));
        ret = extent_write_cache_pages(mapping, wbc, &epd);
-       btrfs_zoned_data_reloc_unlock(inode);
+       btrfs_zoned_data_reloc_unlock(BTRFS_I(inode));
        ASSERT(ret <= 0);
        if (ret < 0) {
                end_write_bio(&epd, ret);
diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index e3eaf03a3422..a7b4cd6dd9f4 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -355,20 +355,20 @@ static inline void btrfs_clear_treelog_bg(struct btrfs_block_group *bg)
        spin_unlock(&fs_info->treelog_bg_lock);
 }
 
-static inline void btrfs_zoned_data_reloc_lock(struct inode *inode)
+static inline void btrfs_zoned_data_reloc_lock(struct btrfs_inode *inode)
 {
-       struct btrfs_root *root = BTRFS_I(inode)->root;
+       struct btrfs_root *root = inode->root;
 
        if (btrfs_is_data_reloc_root(root) && btrfs_is_zoned(root->fs_info))
-               btrfs_inode_lock(inode, 0);
+               btrfs_inode_lock(&inode->vfs_inode, 0);
 }
 
-static inline void btrfs_zoned_data_reloc_unlock(struct inode *inode)
+static inline void btrfs_zoned_data_reloc_unlock(struct btrfs_inode *inode)
 {
-       struct btrfs_root *root = BTRFS_I(inode)->root;
+       struct btrfs_root *root = inode->root;
 
        if (btrfs_is_data_reloc_root(root) && btrfs_is_zoned(root->fs_info))
-               btrfs_inode_unlock(inode, 0);
+               btrfs_inode_unlock(&inode->vfs_inode, 0);
 }
 
 #endif