Re: [PATCH 3/8] staging: erofs: add error handling for xattr submodule

Chao Yu
2018-08-13T02:01:13Z

On 2018/8/12 22:01, Chao Yu wrote:
> From: Gao Xiang <gaoxiang25@huawei.com>
>
> This patch enhances the missing error handling code for
> xattr submodule, which improves the stability for the rare cases.
>
> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
> Reviewed-by: Chao Yu <yuchao0@huawei.com>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> drivers/staging/erofs/internal.h | 6 +-
> drivers/staging/erofs/xattr.c | 120 ++++++++++++++++++++-----------
> 2 files changed, 83 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
> index a756abeff7e9..8951e01216e3 100644
> --- a/drivers/staging/erofs/internal.h
> +++ b/drivers/staging/erofs/internal.h
> @@ -485,10 +485,10 @@ struct erofs_map_blocks_iter {
>
>
> static inline struct page *
> -erofs_get_inline_page_nofail(struct inode *inode,
> - erofs_blk_t blkaddr)
> +erofs_get_inline_page(struct inode *inode,
> + erofs_blk_t blkaddr)
> {
> - return erofs_get_meta_page_nofail(inode->i_sb,
> + return erofs_get_meta_page(inode->i_sb,
> blkaddr, S_ISDIR(inode->i_mode));
> }
>
> diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
> index 2593c856b079..1b5815fc70db 100644
> --- a/drivers/staging/erofs/xattr.c
> +++ b/drivers/staging/erofs/xattr.c
> @@ -24,16 +24,25 @@ struct xattr_iter {
>
> static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
> {
> - /* only init_inode_xattrs use non-atomic once */
> + /* the only user of kunmap() is 'init_inode_xattrs' */
> if (unlikely(!atomic))
> kunmap(it->page);
> else
> kunmap_atomic(it->kaddr);
> +
> unlock_page(it->page);
> put_page(it->page);
> }
>
> -static void init_inode_xattrs(struct inode *inode)
> +static inline void xattr_iter_end_final(struct xattr_iter *it)
> +{
> + if (unlikely(it->page == NULL))
> + return;
> +
> + xattr_iter_end(it, true);
> +}
> +
> +static int init_inode_xattrs(struct inode *inode)
> {
> struct xattr_iter it;
> unsigned i;
> @@ -44,7 +53,7 @@ static void init_inode_xattrs(struct inode *inode)
> bool atomic_map;
>
> if (likely(inode_has_inited_xattr(inode)))
> - return;
> + return 0;
>
> vi = EROFS_V(inode);
> BUG_ON(!vi->xattr_isize);
> @@ -54,8 +63,9 @@ static void init_inode_xattrs(struct inode *inode)
> 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_inline_page_nofail(inode, it.blkaddr);
> - BUG_ON(IS_ERR(it.page));
> + it.page = erofs_get_inline_page(inode, it.blkaddr);
> + if (IS_ERR(it.page))
> + return PTR_ERR(it.page);
>
> /* read in shared xattr array (non-atomic, see kmalloc below) */
> it.kaddr = kmap(it.page);
> @@ -64,9 +74,12 @@ static void init_inode_xattrs(struct inode *inode)
> ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
>
> vi->xattr_shared_count = ih->h_shared_count;
> - vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
> - vi->xattr_shared_count, sizeof(unsigned),
> - GFP_KERNEL | __GFP_NOFAIL);
> + vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
> + sizeof(unsigned), GFP_KERNEL);
> + if (unlikely(vi->xattr_shared_xattrs == NULL)) {
> + xattr_iter_end(&it, atomic_map);
> + return -ENOMEM;
> + }
>
> /* let's skip ibody header */
> it.ofs += sizeof(struct erofs_xattr_ibody_header);
> @@ -77,9 +90,10 @@ static void init_inode_xattrs(struct inode *inode)
> BUG_ON(it.ofs != EROFS_BLKSIZ);
> xattr_iter_end(&it, atomic_map);
>
> - it.page = erofs_get_meta_page_nofail(sb,
> + it.page = erofs_get_meta_page(sb,
> ++it.blkaddr, S_ISDIR(inode->i_mode));
> - BUG_ON(IS_ERR(it.page));
> + if (IS_ERR(it.page))
> + return PTR_ERR(it.page);
>
> it.kaddr = kmap_atomic(it.page);
> atomic_map = true;
> @@ -92,6 +106,7 @@ static void init_inode_xattrs(struct inode *inode)
> xattr_iter_end(&it, atomic_map);
>
> inode_set_inited_xattr(inode);
> + return 0;
> }
>
> struct xattr_iter_handlers {
> @@ -101,19 +116,24 @@ struct xattr_iter_handlers {
> void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
> };
>
> -static void xattr_iter_fixup(struct xattr_iter *it)
> +static inline int xattr_iter_fixup(struct xattr_iter *it)
> {
> - if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
> - xattr_iter_end(it, true);
> + if (likely(it->ofs < EROFS_BLKSIZ))
> + return 0;
>
> - it->blkaddr += erofs_blknr(it->ofs);
> - it->page = erofs_get_meta_page_nofail(it->sb,
> - it->blkaddr, false);
> - BUG_ON(IS_ERR(it->page));
> + xattr_iter_end(it, true);
>
> - it->kaddr = kmap_atomic(it->page);
> - it->ofs = erofs_blkoff(it->ofs);
> + it->blkaddr += erofs_blknr(it->ofs);
> +
> + it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
> + if (IS_ERR(it->page)) {
> + it->page = NULL;
> + return PTR_ERR(it->page);

As LKP reported, we need to fix this as below:

err = PTR_ERR(it->page);
it->page = NULL;
return err;

Thanks,

> }
> +
> + it->kaddr = kmap_atomic(it->page);
> + it->ofs = erofs_blkoff(it->ofs);
> + return 0;
> }
>
> static int inline_xattr_iter_begin(struct xattr_iter *it,
> @@ -134,22 +154,25 @@ 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_inline_page_nofail(inode, it->blkaddr);
> - BUG_ON(IS_ERR(it->page));
> - it->kaddr = kmap_atomic(it->page);
> + it->page = erofs_get_inline_page(inode, it->blkaddr);
> + if (IS_ERR(it->page))
> + return PTR_ERR(it->page);
>
> + it->kaddr = kmap_atomic(it->page);
> return vi->xattr_isize - xattr_header_sz;
> }
>
> static int xattr_foreach(struct xattr_iter *it,
> - struct xattr_iter_handlers *op, unsigned *tlimit)
> + const struct xattr_iter_handlers *op, unsigned *tlimit)
> {
> struct erofs_xattr_entry entry;
> unsigned value_sz, processed, slice;
> int err;
>
> /* 0. fixup blkaddr, ofs, ipage */
> - xattr_iter_fixup(it);
> + err = xattr_iter_fixup(it);
> + if (unlikely(err))
> + return err;
>
> /*
> * 1. read xattr entry to the memory,
> @@ -181,7 +204,9 @@ static int xattr_foreach(struct xattr_iter *it,
> if (it->ofs >= EROFS_BLKSIZ) {
> BUG_ON(it->ofs > EROFS_BLKSIZ);
>
> - xattr_iter_fixup(it);
> + err = xattr_iter_fixup(it);
> + if (unlikely(err))
> + goto out;
> it->ofs = 0;
> }
>
> @@ -213,7 +238,10 @@ static int xattr_foreach(struct xattr_iter *it,
> while (processed < value_sz) {
> if (it->ofs >= EROFS_BLKSIZ) {
> BUG_ON(it->ofs > EROFS_BLKSIZ);
> - xattr_iter_fixup(it);
> +
> + err = xattr_iter_fixup(it);
> + if (unlikely(err))
> + goto out;
> it->ofs = 0;
> }
>
> @@ -273,7 +301,7 @@ static void xattr_copyvalue(struct xattr_iter *_it,
> memcpy(it->buffer + processed, buf, len);
> }
>
> -static struct xattr_iter_handlers find_xattr_handlers = {
> +static const struct xattr_iter_handlers find_xattr_handlers = {
> .entry = xattr_entrymatch,
> .name = xattr_namematch,
> .alloc_buffer = xattr_checkbuffer,
> @@ -294,8 +322,11 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
> ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
> if (ret >= 0)
> break;
> +
> + if (unlikely(ret != -ENOATTR)) /* -ENOMEM, -EIO, etc. */
> + break;
> }
> - xattr_iter_end(&it->it, true);
> + xattr_iter_end_final(&it->it);
>
> return ret < 0 ? ret : it->buffer_size;
> }
> @@ -318,9 +349,10 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
> if (i)
> xattr_iter_end(&it->it, true);
>
> - it->it.page = erofs_get_meta_page_nofail(sb,
> - blkaddr, false);
> - BUG_ON(IS_ERR(it->it.page));
> + it->it.page = erofs_get_meta_page(sb, blkaddr, false);
> + if (IS_ERR(it->it.page))
> + return PTR_ERR(it->it.page);
> +
> it->it.kaddr = kmap_atomic(it->it.page);
> it->it.blkaddr = blkaddr;
> }
> @@ -328,9 +360,12 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
> ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
> if (ret >= 0)
> break;
> +
> + if (unlikely(ret != -ENOATTR)) /* -ENOMEM, -EIO, etc. */
> + break;
> }
> if (vi->xattr_shared_count)
> - xattr_iter_end(&it->it, true);
> + xattr_iter_end_final(&it->it);
>
> return ret < 0 ? ret : it->buffer_size;
> }
> @@ -355,7 +390,9 @@ int erofs_getxattr(struct inode *inode, int index,
> if (unlikely(name == NULL))
> return -EINVAL;
>
> - init_inode_xattrs(inode);
> + ret = init_inode_xattrs(inode);
> + if (unlikely(ret < 0))
> + return ret;
>
> it.index = index;
>
> @@ -498,7 +535,7 @@ static int xattr_skipvalue(struct xattr_iter *_it,
> return 1;
> }
>
> -static struct xattr_iter_handlers list_xattr_handlers = {
> +static const struct xattr_iter_handlers list_xattr_handlers = {
> .entry = xattr_entrylist,
> .name = xattr_namelist,
> .alloc_buffer = xattr_skipvalue,
> @@ -520,7 +557,7 @@ static int inline_listxattr(struct listxattr_iter *it)
> if (ret < 0)
> break;
> }
> - xattr_iter_end(&it->it, true);
> + xattr_iter_end_final(&it->it);
> return ret < 0 ? ret : it->buffer_ofs;
> }
>
> @@ -542,9 +579,10 @@ static int shared_listxattr(struct listxattr_iter *it)
> if (i)
> xattr_iter_end(&it->it, true);
>
> - it->it.page = erofs_get_meta_page_nofail(sb,
> - blkaddr, false);
> - BUG_ON(IS_ERR(it->it.page));
> + it->it.page = erofs_get_meta_page(sb, blkaddr, false);
> + if (IS_ERR(it->it.page))
> + return PTR_ERR(it->it.page);
> +
> it->it.kaddr = kmap_atomic(it->it.page);
> it->it.blkaddr = blkaddr;
> }
> @@ -554,7 +592,7 @@ static int shared_listxattr(struct listxattr_iter *it)
> break;
> }
> if (vi->xattr_shared_count)
> - xattr_iter_end(&it->it, true);
> + xattr_iter_end_final(&it->it);
>
> return ret < 0 ? ret : it->buffer_ofs;
> }
> @@ -565,7 +603,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
> int ret;
> struct listxattr_iter it;
>
> - init_inode_xattrs(d_inode(dentry));
> + ret = init_inode_xattrs(d_inode(dentry));
> + if (unlikely(ret < 0))
> + return ret;
>
> it.dentry = dentry;
> it.buffer = buffer;
>