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Message-ID: <Y6Pnh98KZj0D+FUR@iweiny-desk3>
Date: Wed, 21 Dec 2022 21:13:43 -0800
From: Ira Weiny <ira.weiny@...el.com>
To: "Fabio M. De Francesco" <fmdefrancesco@...il.com>
CC: Evgeniy Dushistov <dushistov@...l.ru>,
Al Viro <viro@...iv.linux.org.uk>,
<linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
<linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH v4 2/3] fs/ufs: Change the signature of ufs_get_page()
On Wed, Dec 21, 2022 at 06:28:01PM +0100, Fabio M. De Francesco wrote:
> Change the signature of ufs_get_page() in order to prepare this function
> to the conversion to the use of kmap_local_page(). Change also those call
> sites which are required to conform its invocations to the new
> signature.
>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Suggested-by: Al Viro <viro@...iv.linux.org.uk>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
> ---
> fs/ufs/dir.c | 49 +++++++++++++++++++++----------------------------
> 1 file changed, 21 insertions(+), 28 deletions(-)
>
> diff --git a/fs/ufs/dir.c b/fs/ufs/dir.c
> index 69f78583c9c1..9fa86614d2d1 100644
> --- a/fs/ufs/dir.c
> +++ b/fs/ufs/dir.c
> @@ -185,7 +185,7 @@ static bool ufs_check_page(struct page *page)
> return false;
> }
>
> -static struct page *ufs_get_page(struct inode *dir, unsigned long n)
> +static void *ufs_get_page(struct inode *dir, unsigned long n, struct page **p)
> {
> struct address_space *mapping = dir->i_mapping;
> struct page *page = read_mapping_page(mapping, n, NULL);
> @@ -195,8 +195,10 @@ static struct page *ufs_get_page(struct inode *dir, unsigned long n)
> if (!ufs_check_page(page))
> goto fail;
> }
> + *p = page;
> + return page_address(page);
> }
> - return page;
> + return ERR_CAST(page);
>
> fail:
> ufs_put_page(page);
> @@ -227,15 +229,12 @@ ufs_next_entry(struct super_block *sb, struct ufs_dir_entry *p)
>
> struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p)
> {
> - struct page *page = ufs_get_page(dir, 0);
> - struct ufs_dir_entry *de = NULL;
> + struct ufs_dir_entry *de = ufs_get_page(dir, 0, p);
I don't know why but ufs_get_page() returning an address read really odd to me.
But rolling around my head alternative names nothing seems better than this.
>
> - if (!IS_ERR(page)) {
> - de = ufs_next_entry(dir->i_sb,
> - (struct ufs_dir_entry *)page_address(page));
> - *p = page;
> - }
> - return de;
> + if (!IS_ERR(de))
> + return ufs_next_entry(dir->i_sb, de);
> + else
> + return NULL;
> }
>
> /*
> @@ -273,11 +272,10 @@ struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
> start = 0;
> n = start;
> do {
> - char *kaddr;
> - page = ufs_get_page(dir, n);
> - if (!IS_ERR(page)) {
> - kaddr = page_address(page);
> - de = (struct ufs_dir_entry *) kaddr;
> + char *kaddr = ufs_get_page(dir, n, &page);
> +
> + if (!IS_ERR(kaddr)) {
> + de = (struct ufs_dir_entry *)kaddr;
> kaddr += ufs_last_byte(dir, n) - reclen;
> while ((char *) de <= kaddr) {
> if (ufs_match(sb, namelen, name, de))
> @@ -328,12 +326,10 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
> for (n = 0; n <= npages; n++) {
> char *dir_end;
>
> - page = ufs_get_page(dir, n);
> - err = PTR_ERR(page);
> - if (IS_ERR(page))
> - goto out;
> + kaddr = ufs_get_page(dir, n, &page);
> + if (IS_ERR(kaddr))
> + return PTR_ERR(kaddr);
> lock_page(page);
> - kaddr = page_address(page);
> dir_end = kaddr + ufs_last_byte(dir, n);
> de = (struct ufs_dir_entry *)kaddr;
> kaddr += PAGE_SIZE - reclen;
> @@ -395,7 +391,6 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
> /* OFFSET_CACHE */
> out_put:
> ufs_put_page(page);
> -out:
> return err;
> out_unlock:
> unlock_page(page);
> @@ -429,6 +424,7 @@ ufs_readdir(struct file *file, struct dir_context *ctx)
> unsigned chunk_mask = ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
> bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
> unsigned flags = UFS_SB(sb)->s_flags;
> + struct page *page;
NIT: Does page now leave the scope of the for loop?
>
> UFSD("BEGIN\n");
>
> @@ -439,16 +435,14 @@ ufs_readdir(struct file *file, struct dir_context *ctx)
> char *kaddr, *limit;
> struct ufs_dir_entry *de;
Couldn't that be declared here?
Regardless I don't think this is broken.
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
>
> - struct page *page = ufs_get_page(inode, n);
> -
> - if (IS_ERR(page)) {
> + kaddr = ufs_get_page(inode, n, &page);
> + if (IS_ERR(kaddr)) {
> ufs_error(sb, __func__,
> "bad page in #%lu",
> inode->i_ino);
> ctx->pos += PAGE_SIZE - offset;
> return -EIO;
> }
> - kaddr = page_address(page);
> if (unlikely(need_revalidate)) {
> if (offset) {
> offset = ufs_validate_entry(sb, kaddr, offset, chunk_mask);
> @@ -595,12 +589,11 @@ int ufs_empty_dir(struct inode * inode)
> for (i = 0; i < npages; i++) {
> char *kaddr;
> struct ufs_dir_entry *de;
> - page = ufs_get_page(inode, i);
>
> - if (IS_ERR(page))
> + kaddr = ufs_get_page(inode, i, &page);
> + if (IS_ERR(kaddr))
> continue;
>
> - kaddr = page_address(page);
> de = (struct ufs_dir_entry *)kaddr;
> kaddr += ufs_last_byte(inode, i) - UFS_DIR_REC_LEN(1);
>
> --
> 2.39.0
>
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