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SubjectRe: [RFC PATCH 01/12] afs: Sort out symlink reading
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On Wed, 2021-07-21 at 14:44 +0100, David Howells wrote:
> afs_readpage() doesn't get a file pointer when called for a symlink, so
> separate it from regular file pointer handling.
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
> fs/afs/file.c | 14 +++++++++-----
> fs/afs/inode.c | 6 +++---
> fs/afs/internal.h | 3 ++-
> 3 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/fs/afs/file.c b/fs/afs/file.c
> index ca0d993add65..c9c21ad0e7c9 100644
> --- a/fs/afs/file.c
> +++ b/fs/afs/file.c
> @@ -19,6 +19,7 @@
>
> static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
> static int afs_readpage(struct file *file, struct page *page);
> +static int afs_symlink_readpage(struct file *file, struct page *page);
> static void afs_invalidatepage(struct page *page, unsigned int offset,
> unsigned int length);
> static int afs_releasepage(struct page *page, gfp_t gfp_flags);
> @@ -46,7 +47,7 @@ const struct inode_operations afs_file_inode_operations = {
> .permission = afs_permission,
> };
>
> -const struct address_space_operations afs_fs_aops = {
> +const struct address_space_operations afs_file_aops = {
> .readpage = afs_readpage,
> .readahead = afs_readahead,
> .set_page_dirty = afs_set_page_dirty,
> @@ -60,6 +61,12 @@ const struct address_space_operations afs_fs_aops = {
> .writepages = afs_writepages,
> };
>
> +const struct address_space_operations afs_symlink_aops = {
> + .readpage = afs_symlink_readpage,
> + .releasepage = afs_releasepage,
> + .invalidatepage = afs_invalidatepage,
> +};
> +
> static const struct vm_operations_struct afs_vm_ops = {
> .fault = filemap_fault,
> .map_pages = filemap_map_pages,
> @@ -321,7 +328,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq)
> afs_fetch_data(fsreq->vnode, fsreq);
> }
>
> -static int afs_symlink_readpage(struct page *page)
> +static int afs_symlink_readpage(struct file *file, struct page *page)
> {
> struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
> struct afs_read *fsreq;


I wonder...would you be better served here by not using page_readlink
for symlinks and instead use simple_get_link and roll your own readlink
operation. It seems a bit more direct, and AFS seems to be the only
caller of page_readlink.

> @@ -386,9 +393,6 @@ const struct netfs_read_request_ops afs_req_ops = {
>
> static int afs_readpage(struct file *file, struct page *page)
> {
> - if (!file)
> - return afs_symlink_readpage(page);
> -
> return netfs_readpage(file, page, &afs_req_ops, NULL);
> }
>
> diff --git a/fs/afs/inode.c b/fs/afs/inode.c
> index bef6f5ccfb09..cf7b66957c6f 100644
> --- a/fs/afs/inode.c
> +++ b/fs/afs/inode.c
> @@ -105,7 +105,7 @@ static int afs_inode_init_from_status(struct afs_operation *op,
> inode->i_mode = S_IFREG | (status->mode & S_IALLUGO);
> inode->i_op = &afs_file_inode_operations;
> inode->i_fop = &afs_file_operations;
> - inode->i_mapping->a_ops = &afs_fs_aops;
> + inode->i_mapping->a_ops = &afs_file_aops;
> break;
> case AFS_FTYPE_DIR:
> inode->i_mode = S_IFDIR | (status->mode & S_IALLUGO);
> @@ -123,11 +123,11 @@ static int afs_inode_init_from_status(struct afs_operation *op,
> inode->i_mode = S_IFDIR | 0555;
> inode->i_op = &afs_mntpt_inode_operations;
> inode->i_fop = &afs_mntpt_file_operations;
> - inode->i_mapping->a_ops = &afs_fs_aops;
> + inode->i_mapping->a_ops = &afs_symlink_aops;
> } else {
> inode->i_mode = S_IFLNK | status->mode;
> inode->i_op = &afs_symlink_inode_operations;
> - inode->i_mapping->a_ops = &afs_fs_aops;
> + inode->i_mapping->a_ops = &afs_symlink_aops;
> }
> inode_nohighmem(inode);
> break;
> diff --git a/fs/afs/internal.h b/fs/afs/internal.h
> index 791cf02e5696..ccdde00ada8a 100644
> --- a/fs/afs/internal.h
> +++ b/fs/afs/internal.h
> @@ -1050,7 +1050,8 @@ extern void afs_dynroot_depopulate(struct super_block *);
> /*
> * file.c
> */
> -extern const struct address_space_operations afs_fs_aops;
> +extern const struct address_space_operations afs_file_aops;
> +extern const struct address_space_operations afs_symlink_aops;
> extern const struct inode_operations afs_file_inode_operations;
> extern const struct file_operations afs_file_operations;
> extern const struct netfs_read_request_ops afs_req_ops;
>
>

Regardless, this is more reasonable than what's there now.

Reviewed-by: Jeff Layton <jlayton@redhat.com>

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