Re: [PATCH 06/10] ext2: Factor our freeing of xattr block reference

Ritesh Harjani
2022-07-14T12:37:26Z

On 22/07/12 12:54PM, Jan Kara wrote:
> Free of xattr block reference is opencode in two places. Factor it out
> into a separate function and use it.

Looked into the refactoring logic. The patch looks good to me.
Small queries below -

>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> fs/ext2/xattr.c | 90 +++++++++++++++++++++----------------------------
> 1 file changed, 38 insertions(+), 52 deletions(-)
>
> diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
> index 841fa6d9d744..9885294993ef 100644
> --- a/fs/ext2/xattr.c
> +++ b/fs/ext2/xattr.c
> @@ -651,6 +651,42 @@ ext2_xattr_set(struct inode *inode, int name_index, const char *name,
> return error;
> }
>
> +static void ext2_xattr_release_block(struct inode *inode,
> + struct buffer_head *bh)
> +{
> + struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
> +
> + lock_buffer(bh);
> + if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
> + __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
> +
> + /*
> + * This must happen under buffer lock for
> + * ext2_xattr_set2() to reliably detect freed block
> + */
> + mb_cache_entry_delete(ea_block_cache, hash,
> + bh->b_blocknr);
> + /* Free the old block. */
> + ea_bdebug(bh, "freeing");
> + ext2_free_blocks(inode, bh->b_blocknr, 1);
> + /* We let our caller release bh, so we
> + * need to duplicate the buffer before. */
> + get_bh(bh);
> + bforget(bh);
> + unlock_buffer(bh);
> + } else {
> + /* Decrement the refcount only. */
> + le32_add_cpu(&HDR(bh)->h_refcount, -1);
> + dquot_free_block(inode, 1);
> + mark_buffer_dirty(bh);
> + unlock_buffer(bh);
> + ea_bdebug(bh, "refcount now=%d",
> + le32_to_cpu(HDR(bh)->h_refcount));
> + if (IS_SYNC(inode))
> + sync_dirty_buffer(bh);
> + }
> +}
> +
> /*
> * Second half of ext2_xattr_set(): Update the file system.
> */
> @@ -747,34 +783,7 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
> * If there was an old block and we are no longer using it,
> * release the old block.
> */
> - lock_buffer(old_bh);
> - if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
> - __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash);
> -
> - /*
> - * This must happen under buffer lock for
> - * ext2_xattr_set2() to reliably detect freed block
> - */
> - mb_cache_entry_delete(ea_block_cache, hash,
> - old_bh->b_blocknr);
> - /* Free the old block. */
> - ea_bdebug(old_bh, "freeing");
> - ext2_free_blocks(inode, old_bh->b_blocknr, 1);
> - mark_inode_dirty(inode);

^^^ this is not needed because ext2_free_blocks() will take care of it.
Hence you have dropped this in ext2_xattr_release_block()

> - /* We let our caller release old_bh, so we
> - * need to duplicate the buffer before. */
> - get_bh(old_bh);
> - bforget(old_bh);
> - } else {
> - /* Decrement the refcount only. */
> - le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
> - dquot_free_block_nodirty(inode, 1);
> - mark_inode_dirty(inode);

Quick qn -> Don't we need mark_inode_dirty() here?

> - mark_buffer_dirty(old_bh);
> - ea_bdebug(old_bh, "refcount now=%d",
> - le32_to_cpu(HDR(old_bh)->h_refcount));
> - }
> - unlock_buffer(old_bh);
> + ext2_xattr_release_block(inode, old_bh);
> }
>
> cleanup:
> @@ -828,30 +837,7 @@ ext2_xattr_delete_inode(struct inode *inode)
> EXT2_I(inode)->i_file_acl);
> goto cleanup;
> }
> - lock_buffer(bh);
> - if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
> - __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
> -
> - /*
> - * This must happen under buffer lock for ext2_xattr_set2() to
> - * reliably detect freed block
> - */
> - mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
> - bh->b_blocknr);
> - ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
> - get_bh(bh);
> - bforget(bh);
> - unlock_buffer(bh);
> - } else {
> - le32_add_cpu(&HDR(bh)->h_refcount, -1);
> - ea_bdebug(bh, "refcount now=%d",
> - le32_to_cpu(HDR(bh)->h_refcount));
> - unlock_buffer(bh);
> - mark_buffer_dirty(bh);
> - if (IS_SYNC(inode))
> - sync_dirty_buffer(bh);
> - dquot_free_block_nodirty(inode, 1);
> - }
> + ext2_xattr_release_block(inode, bh);
> EXT2_I(inode)->i_file_acl = 0;
>
> cleanup:
> --
> 2.35.3
>