Re: [PATCH v2 4/5] erofs: use meta buffers for xattr operations

From: Liu Bo
Date: Sun Jan 02 2022 - 02:49:29 EST

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On Sun, Jan 02, 2022 at 12:00:16PM +0800, Gao Xiang wrote:
> Get rid of old erofs_get_meta_page() within xattr operations by
> using on-stack meta buffers in order to prepare subpage and folio
> features.
>

Reviewed-by: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx>

> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> ---
> fs/erofs/xattr.c | 134 ++++++++++++++---------------------------------
> 1 file changed, 40 insertions(+), 94 deletions(-)
>
> diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
> index 01c581e93c5f..437ff6e7293d 100644
> --- a/fs/erofs/xattr.c
> +++ b/fs/erofs/xattr.c
> @@ -8,33 +8,13 @@
>
> struct xattr_iter {
> struct super_block *sb;
> - struct page *page;
> + struct erofs_buf buf;
> void *kaddr;
>
> erofs_blk_t blkaddr;
> unsigned int ofs;
> };
>
> -static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
> -{
> - /* the only user of kunmap() is 'init_inode_xattrs' */
> - if (!atomic)
> - kunmap(it->page);
> - else
> - kunmap_atomic(it->kaddr);
> -
> - unlock_page(it->page);
> - put_page(it->page);
> -}
> -
> -static inline void xattr_iter_end_final(struct xattr_iter *it)
> -{
> - if (!it->page)
> - return;
> -
> - xattr_iter_end(it, true);
> -}
> -
> static int init_inode_xattrs(struct inode *inode)
> {
> struct erofs_inode *const vi = EROFS_I(inode);
> @@ -43,7 +23,6 @@ static int init_inode_xattrs(struct inode *inode)
> struct erofs_xattr_ibody_header *ih;
> struct super_block *sb;
> struct erofs_sb_info *sbi;
> - bool atomic_map;
> int ret = 0;
>
> /* the most case is that xattrs of this inode are initialized. */
> @@ -91,26 +70,23 @@ static int init_inode_xattrs(struct inode *inode)
>
> sb = inode->i_sb;
> sbi = EROFS_SB(sb);
> + it.buf = __EROFS_BUF_INITIALIZER;
> it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
> it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
>
> - it.page = erofs_get_meta_page(sb, it.blkaddr);
> - if (IS_ERR(it.page)) {
> - ret = PTR_ERR(it.page);
> + /* read in shared xattr array (non-atomic, see kmalloc below) */
> + it.kaddr = erofs_read_metabuf(&it.buf, sb, it.blkaddr, EROFS_KMAP);
> + if (IS_ERR(it.kaddr)) {
> + ret = PTR_ERR(it.kaddr);
> goto out_unlock;
> }
>
> - /* read in shared xattr array (non-atomic, see kmalloc below) */
> - it.kaddr = kmap(it.page);
> - atomic_map = false;
> -
> ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
> -
> vi->xattr_shared_count = ih->h_shared_count;
> vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
> sizeof(uint), GFP_KERNEL);
> if (!vi->xattr_shared_xattrs) {
> - xattr_iter_end(&it, atomic_map);
> + erofs_put_metabuf(&it.buf);
> ret = -ENOMEM;
> goto out_unlock;
> }
> @@ -122,25 +98,22 @@ static int init_inode_xattrs(struct inode *inode)
> if (it.ofs >= EROFS_BLKSIZ) {
> /* cannot be unaligned */
> DBG_BUGON(it.ofs != EROFS_BLKSIZ);
> - xattr_iter_end(&it, atomic_map);
>
> - it.page = erofs_get_meta_page(sb, ++it.blkaddr);
> - if (IS_ERR(it.page)) {
> + it.kaddr = erofs_read_metabuf(&it.buf, sb, ++it.blkaddr,
> + EROFS_KMAP);
> + if (IS_ERR(it.kaddr)) {
> kfree(vi->xattr_shared_xattrs);
> vi->xattr_shared_xattrs = NULL;
> - ret = PTR_ERR(it.page);
> + ret = PTR_ERR(it.kaddr);
> goto out_unlock;
> }
> -
> - it.kaddr = kmap_atomic(it.page);
> - atomic_map = true;
> it.ofs = 0;
> }
> vi->xattr_shared_xattrs[i] =
> le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs));
> it.ofs += sizeof(__le32);
> }
> - xattr_iter_end(&it, atomic_map);
> + erofs_put_metabuf(&it.buf);
>
> /* paired with smp_mb() at the beginning of the function. */
> smp_mb();
> @@ -172,19 +145,11 @@ static inline int xattr_iter_fixup(struct xattr_iter *it)
> if (it->ofs < EROFS_BLKSIZ)
> return 0;
>
> - xattr_iter_end(it, true);
> -
> it->blkaddr += erofs_blknr(it->ofs);
> -
> - it->page = erofs_get_meta_page(it->sb, it->blkaddr);
> - if (IS_ERR(it->page)) {
> - int err = PTR_ERR(it->page);
> -
> - it->page = NULL;
> - return err;
> - }
> -
> - it->kaddr = kmap_atomic(it->page);
> + it->kaddr = erofs_read_metabuf(&it->buf, it->sb, it->blkaddr,
> + EROFS_KMAP_ATOMIC);
> + if (IS_ERR(it->kaddr))
> + return PTR_ERR(it->kaddr);
> it->ofs = erofs_blkoff(it->ofs);
> return 0;
> }
> @@ -207,11 +172,10 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
> it->blkaddr = erofs_blknr(iloc(sbi, vi->nid) + inline_xattr_ofs);
> it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
>
> - it->page = erofs_get_meta_page(inode->i_sb, it->blkaddr);
> - if (IS_ERR(it->page))
> - return PTR_ERR(it->page);
> -
> - it->kaddr = kmap_atomic(it->page);
> + it->kaddr = erofs_read_metabuf(&it->buf, inode->i_sb, it->blkaddr,
> + EROFS_KMAP_ATOMIC);
> + if (IS_ERR(it->kaddr))
> + return PTR_ERR(it->kaddr);
> return vi->xattr_isize - xattr_header_sz;
> }
>
> @@ -272,7 +236,7 @@ static int xattr_foreach(struct xattr_iter *it,
> it->ofs = 0;
> }
>
> - slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
> + slice = min_t(unsigned int, EROFS_BLKSIZ - it->ofs,
> entry.e_name_len - processed);
>
> /* handle name */
> @@ -307,7 +271,7 @@ static int xattr_foreach(struct xattr_iter *it,
> it->ofs = 0;
> }
>
> - slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
> + slice = min_t(unsigned int, EROFS_BLKSIZ - it->ofs,
> value_sz - processed);
> op->value(it, processed, it->kaddr + it->ofs, slice);
> it->ofs += slice;
> @@ -386,8 +350,6 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
> if (ret != -ENOATTR)
> break;
> }
> - xattr_iter_end_final(&it->it);
> -
> return ret ? ret : it->buffer_size;
> }
>
> @@ -404,26 +366,16 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
> xattrblock_addr(sbi, vi->xattr_shared_xattrs[i]);
>
> it->it.ofs = xattrblock_offset(sbi, vi->xattr_shared_xattrs[i]);
> -
> - if (!i || blkaddr != it->it.blkaddr) {
> - if (i)
> - xattr_iter_end(&it->it, true);
> -
> - it->it.page = erofs_get_meta_page(sb, blkaddr);
> - if (IS_ERR(it->it.page))
> - return PTR_ERR(it->it.page);
> -
> - it->it.kaddr = kmap_atomic(it->it.page);
> - it->it.blkaddr = blkaddr;
> - }
> + it->it.kaddr = erofs_read_metabuf(&it->it.buf, sb, blkaddr,
> + EROFS_KMAP_ATOMIC);
> + if (IS_ERR(it->it.kaddr))
> + return PTR_ERR(it->it.kaddr);
> + it->it.blkaddr = blkaddr;
>
> ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
> if (ret != -ENOATTR)
> break;
> }
> - if (vi->xattr_shared_count)
> - xattr_iter_end_final(&it->it);
> -
> return ret ? ret : it->buffer_size;
> }
>
> @@ -452,10 +404,11 @@ int erofs_getxattr(struct inode *inode, int index,
> return ret;
>
> it.index = index;
> -
> it.name.len = strlen(name);
> if (it.name.len > EROFS_NAME_LEN)
> return -ERANGE;
> +
> + it.it.buf = __EROFS_BUF_INITIALIZER;
> it.name.name = name;
>
> it.buffer = buffer;
> @@ -465,6 +418,7 @@ int erofs_getxattr(struct inode *inode, int index,
> ret = inline_getxattr(inode, &it);
> if (ret == -ENOATTR)
> ret = shared_getxattr(inode, &it);
> + erofs_put_metabuf(&it.it.buf);
> return ret;
> }
>
> @@ -607,7 +561,6 @@ static int inline_listxattr(struct listxattr_iter *it)
> if (ret)
> break;
> }
> - xattr_iter_end_final(&it->it);
> return ret ? ret : it->buffer_ofs;
> }
>
> @@ -625,25 +578,16 @@ static int shared_listxattr(struct listxattr_iter *it)
> xattrblock_addr(sbi, vi->xattr_shared_xattrs[i]);
>
> it->it.ofs = xattrblock_offset(sbi, vi->xattr_shared_xattrs[i]);
> - if (!i || blkaddr != it->it.blkaddr) {
> - if (i)
> - xattr_iter_end(&it->it, true);
> -
> - it->it.page = erofs_get_meta_page(sb, blkaddr);
> - if (IS_ERR(it->it.page))
> - return PTR_ERR(it->it.page);
> -
> - it->it.kaddr = kmap_atomic(it->it.page);
> - it->it.blkaddr = blkaddr;
> - }
> + it->it.kaddr = erofs_read_metabuf(&it->it.buf, sb, blkaddr,
> + EROFS_KMAP_ATOMIC);
> + if (IS_ERR(it->it.kaddr))
> + return PTR_ERR(it->it.kaddr);
> + it->it.blkaddr = blkaddr;
>
> ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
> if (ret)
> break;
> }
> - if (vi->xattr_shared_count)
> - xattr_iter_end_final(&it->it);
> -
> return ret ? ret : it->buffer_ofs;
> }
>
> @@ -659,6 +603,7 @@ ssize_t erofs_listxattr(struct dentry *dentry,
> if (ret)
> return ret;
>
> + it.it.buf = __EROFS_BUF_INITIALIZER;
> it.dentry = dentry;
> it.buffer = buffer;
> it.buffer_size = buffer_size;
> @@ -667,9 +612,10 @@ ssize_t erofs_listxattr(struct dentry *dentry,
> it.it.sb = dentry->d_sb;
>
> ret = inline_listxattr(&it);
> - if (ret < 0 && ret != -ENOATTR)
> - return ret;
> - return shared_listxattr(&it);
> + if (ret >= 0 || ret == -ENOATTR)
> + ret = shared_listxattr(&it);
> + erofs_put_metabuf(&it.it.buf);
> + return ret;
> }
>
> #ifdef CONFIG_EROFS_FS_POSIX_ACL
> --
> 2.24.4

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