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Message-ID: <1cbbd501-bd81-4df8-a887-8c07e0469ae1@linux.alibaba.com>
Date: Mon, 2 Sep 2024 16:12:31 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: Yiyang Wu <toolmanp@...p.cc>
Cc: linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH V3 2/2] erofs: refactor read_inode calling convention
On 2024/9/2 16:04, Yiyang Wu wrote:
> Refactor out the iop binding behavior out of the erofs_fill_symlink
> and move erofs_buf into the erofs_read_inode, so that erofs_fill_inode
> can only deal with inode operation bindings and can be decoupled from
> metabuf operations. This results in better calling conventions.
>
> Note that after this patch, we do not need erofs_buf and ofs as
> parameters any more when calling erofs_read_inode as
> all the data operations are now included in itself.
>
> Suggested-by: Al Viro <viro@...iv.linux.org.uk>
> Link: https://lore.kernel.org/all/20240425222847.GN2118490@ZenIV/
> Signed-off-by: Yiyang Wu <toolmanp@...p.cc>
> ---
> fs/erofs/inode.c | 120 +++++++++++++++++++++++------------------------
> 1 file changed, 58 insertions(+), 62 deletions(-)
>
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index 40d3f4921d81..e9712af9a730 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -8,8 +8,33 @@
>
> #include <trace/events/erofs.h>
>
> -static void *erofs_read_inode(struct erofs_buf *buf,
> - struct inode *inode, unsigned int *ofs)
> +static int erofs_fill_symlink(struct inode *inode, void *kaddr,
> + unsigned int m_pofs)
> +{
> + struct erofs_inode *vi = EROFS_I(inode);
> + unsigned int bsz = i_blocksize(inode);
> +
> + /* if it cannot be handled with fast symlink scheme */
> + if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
> + inode->i_size >= bsz || inode->i_size < 0) {
> + return 0;
> + }
> +
> + m_pofs += vi->xattr_isize;
> + /* inline symlink data shouldn't cross block boundary */
> + if (m_pofs + inode->i_size > bsz) {
> + erofs_err(inode->i_sb, "inline data cross block boundary @ nid %llu",
> + vi->nid);
> + DBG_BUGON(1);
> + return -EFSCORRUPTED;
> + }
> +
> + inode->i_link = kmemdup_nul(kaddr + m_pofs, inode->i_size, GFP_KERNEL);
> +
> + return inode->i_link ? 0 : -ENOMEM;
> +}
> +
> +static int erofs_read_inode(struct inode *inode)
> {
> struct super_block *sb = inode->i_sb;
> struct erofs_sb_info *sbi = EROFS_SB(sb);
> @@ -20,20 +45,21 @@ static void *erofs_read_inode(struct erofs_buf *buf,
> struct erofs_inode_compact *dic;
> struct erofs_inode_extended *die, *copied = NULL;
> union erofs_inode_i_u iu;
> - unsigned int ifmt;
> - int err;
> + struct erofs_buf buf;
Should be
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
Otherwise buf itself will be left uninitialized.
> + unsigned int ifmt, ofs;
> + int err = 0;
>
> blkaddr = erofs_blknr(sb, inode_loc);
> - *ofs = erofs_blkoff(sb, inode_loc);
> + ofs = erofs_blkoff(sb, inode_loc);
>
> - kaddr = erofs_read_metabuf(buf, sb, erofs_pos(sb, blkaddr), EROFS_KMAP);
> + kaddr = erofs_read_metabuf(&buf, sb, erofs_pos(sb, blkaddr), EROFS_KMAP);
> if (IS_ERR(kaddr)) {
> erofs_err(sb, "failed to get inode (nid: %llu) page, err %ld",
> vi->nid, PTR_ERR(kaddr));
> - return kaddr;
> + return PTR_ERR(kaddr);
> }
>
> - dic = kaddr + *ofs;
> + dic = kaddr + ofs;
> ifmt = le16_to_cpu(dic->i_format);
> if (ifmt & ~EROFS_I_ALL) {
> erofs_err(sb, "unsupported i_format %u of nid %llu",
> @@ -54,11 +80,11 @@ static void *erofs_read_inode(struct erofs_buf *buf,
> case EROFS_INODE_LAYOUT_EXTENDED:
> vi->inode_isize = sizeof(struct erofs_inode_extended);
> /* check if the extended inode acrosses block boundary */
> - if (*ofs + vi->inode_isize <= sb->s_blocksize) {
> - *ofs += vi->inode_isize;
> + if (ofs + vi->inode_isize <= sb->s_blocksize) {
> + ofs += vi->inode_isize;
> die = (struct erofs_inode_extended *)dic;
> } else {
> - const unsigned int gotten = sb->s_blocksize - *ofs;
> + const unsigned int gotten = sb->s_blocksize - ofs;
>
> copied = kmalloc(vi->inode_isize, GFP_KERNEL);
> if (!copied) {
> @@ -66,16 +92,16 @@ static void *erofs_read_inode(struct erofs_buf *buf,
> goto err_out;
> }
> memcpy(copied, dic, gotten);
> - kaddr = erofs_read_metabuf(buf, sb, erofs_pos(sb, blkaddr + 1),
> + kaddr = erofs_read_metabuf(&buf, sb, erofs_pos(sb, blkaddr + 1),
> EROFS_KMAP);
> if (IS_ERR(kaddr)) {
> erofs_err(sb, "failed to get inode payload block (nid: %llu), err %ld",
> vi->nid, PTR_ERR(kaddr));
> kfree(copied);
> - return kaddr;
> + return PTR_ERR(kaddr);
> }
> - *ofs = vi->inode_isize - gotten;
> - memcpy((u8 *)copied + gotten, kaddr, *ofs);
> + ofs = vi->inode_isize - gotten;
> + memcpy((u8 *)copied + gotten, kaddr, ofs);
> die = copied;
> }
> vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
> @@ -91,11 +117,10 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>
> inode->i_size = le64_to_cpu(die->i_size);
> kfree(copied);
> - copied = NULL;
> break;
> case EROFS_INODE_LAYOUT_COMPACT:
> vi->inode_isize = sizeof(struct erofs_inode_compact);
> - *ofs += vi->inode_isize;
> + ofs += vi->inode_isize;
> vi->xattr_isize = erofs_xattr_ibody_size(dic->i_xattr_icount);
>
> inode->i_mode = le16_to_cpu(dic->i_mode);
> @@ -119,6 +144,11 @@ static void *erofs_read_inode(struct erofs_buf *buf,
> case S_IFREG:
> case S_IFDIR:
> case S_IFLNK:
> + if(S_ISLNK(inode->i_mode)) {
> + err = erofs_fill_symlink(inode, kaddr, ofs);
> + if (err)
> + goto err_out;
> + }
> vi->raw_blkaddr = le32_to_cpu(iu.raw_blkaddr);
> break;
> case S_IFCHR:
> @@ -165,59 +195,24 @@ static void *erofs_read_inode(struct erofs_buf *buf,
> inode->i_blocks = round_up(inode->i_size, sb->s_blocksize) >> 9;
> else
> inode->i_blocks = nblks << (sb->s_blocksize_bits - 9);
> - return kaddr;
>
> err_out:
> - DBG_BUGON(1);
> - kfree(copied);
> - erofs_put_metabuf(buf);
> - return ERR_PTR(err);
> -}
> -
> -static int erofs_fill_symlink(struct inode *inode, void *kaddr,
> - unsigned int m_pofs)
> -{
> - struct erofs_inode *vi = EROFS_I(inode);
> - unsigned int bsz = i_blocksize(inode);
> -
> - /* if it cannot be handled with fast symlink scheme */
> - if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
> - inode->i_size >= bsz || inode->i_size < 0) {
> - inode->i_op = &erofs_symlink_iops;
> - return 0;
> - }
> -
> - m_pofs += vi->xattr_isize;
> - /* inline symlink data shouldn't cross block boundary */
> - if (m_pofs + inode->i_size > bsz) {
> - erofs_err(inode->i_sb, "inline data cross block boundary @ nid %llu",
> - vi->nid);
> - DBG_BUGON(1);
> - return -EFSCORRUPTED;
> - }
> -
> - inode->i_link = kmemdup_nul(kaddr + m_pofs, inode->i_size, GFP_KERNEL);
> - if (!inode->i_link)
> - return -ENOMEM;
> -
> - inode->i_op = &erofs_fast_symlink_iops;
> - return 0;
> + DBG_BUGON(err);
> + erofs_put_metabuf(&buf);
> + return err;
> }
>
> static int erofs_fill_inode(struct inode *inode)
> {
> struct erofs_inode *vi = EROFS_I(inode);
> - struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
> - void *kaddr;
> - unsigned int ofs;
> int err = 0;
>
> trace_erofs_fill_inode(inode);
>
> /* read inode base data from disk */
> - kaddr = erofs_read_inode(&buf, inode, &ofs);
> - if (IS_ERR(kaddr))
> - return PTR_ERR(kaddr);
> + err = erofs_read_inode(inode);
> + if (err)
> + return err;
>
> /* setup the new inode */
> switch (inode->i_mode & S_IFMT) {
> @@ -234,9 +229,11 @@ static int erofs_fill_inode(struct inode *inode)
> inode_nohighmem(inode);
> break;
> case S_IFLNK:
> - err = erofs_fill_symlink(inode, kaddr, ofs);
> - if (err)
> - goto out_unlock;
> + if (inode->i_link)
> + inode->i_op = &erofs_fast_symlink_iops;
> + else
> + inode->i_op = &erofs_symlink_iops;
> +
> inode_nohighmem(inode);
> break;
> case S_IFCHR:
> @@ -269,7 +266,6 @@ static int erofs_fill_inode(struct inode *inode)
> #endif
> }
> out_unlock:
I mean since `return err` is the only useful statement for
label `out_unlock`.
You could just remove it entirely and replace all
`goto out_unlock` to `return err`;
the name `out_unlock` itself is also meaningless due to
this patch.
Thanks,
Gao Xiang
> - erofs_put_metabuf(&buf);
> return err;
> }
>
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