On Fri, Aug 29, 2025 at 04:56:24PM -0700, Joanne Koong wrote:
> Add a void *private arg for read and readahead which filesystems that
> pass in custom read callbacks can use. Stash this in the existing
> private field in the iomap_iter.
>
> Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
Seems reasonable to me, though what happens if an iomap user passes a
non-NULL private pointer here but no folio ops; and then iomap_readahead
tries to store a bio in there?
(This is why I disliked that previous patch so strongly)
--D
> ---
> block/fops.c | 4 ++--
> fs/erofs/data.c | 4 ++--
> fs/gfs2/aops.c | 4 ++--
> fs/iomap/buffered-io.c | 8 ++++++--
> fs/xfs/xfs_aops.c | 4 ++--
> fs/zonefs/file.c | 4 ++--
> include/linux/iomap.h | 4 ++--
> 7 files changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/block/fops.c b/block/fops.c
> index b42e16d0eb35..57ae886c7b1a 100644
> --- a/block/fops.c
> +++ b/block/fops.c
> @@ -533,12 +533,12 @@ const struct address_space_operations def_blk_aops = {
> #else /* CONFIG_BUFFER_HEAD */
> static int blkdev_read_folio(struct file *file, struct folio *folio)
> {
> - return iomap_read_folio(folio, &blkdev_iomap_ops, NULL);
> + return iomap_read_folio(folio, &blkdev_iomap_ops, NULL, NULL);
> }
>
> static void blkdev_readahead(struct readahead_control *rac)
> {
> - iomap_readahead(rac, &blkdev_iomap_ops, NULL);
> + iomap_readahead(rac, &blkdev_iomap_ops, NULL, NULL);
> }
>
> static ssize_t blkdev_writeback_range(struct iomap_writepage_ctx *wpc,
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index ea451f233263..2ea338448ca1 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -371,7 +371,7 @@ static int erofs_read_folio(struct file *file, struct folio *folio)
> {
> trace_erofs_read_folio(folio, true);
>
> - return iomap_read_folio(folio, &erofs_iomap_ops, NULL);
> + return iomap_read_folio(folio, &erofs_iomap_ops, NULL, NULL);
> }
>
> static void erofs_readahead(struct readahead_control *rac)
> @@ -379,7 +379,7 @@ static void erofs_readahead(struct readahead_control *rac)
> trace_erofs_readahead(rac->mapping->host, readahead_index(rac),
> readahead_count(rac), true);
>
> - return iomap_readahead(rac, &erofs_iomap_ops, NULL);
> + return iomap_readahead(rac, &erofs_iomap_ops, NULL, NULL);
> }
>
> static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
> diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
> index bf531bcfd8a0..211a0f7b1416 100644
> --- a/fs/gfs2/aops.c
> +++ b/fs/gfs2/aops.c
> @@ -428,7 +428,7 @@ static int gfs2_read_folio(struct file *file, struct folio *folio)
>
> if (!gfs2_is_jdata(ip) ||
> (i_blocksize(inode) == PAGE_SIZE && !folio_buffers(folio))) {
> - error = iomap_read_folio(folio, &gfs2_iomap_ops, NULL);
> + error = iomap_read_folio(folio, &gfs2_iomap_ops, NULL, NULL);
> } else if (gfs2_is_stuffed(ip)) {
> error = stuffed_read_folio(ip, folio);
> } else {
> @@ -503,7 +503,7 @@ static void gfs2_readahead(struct readahead_control *rac)
> else if (gfs2_is_jdata(ip))
> mpage_readahead(rac, gfs2_block_map);
> else
> - iomap_readahead(rac, &gfs2_iomap_ops, NULL);
> + iomap_readahead(rac, &gfs2_iomap_ops, NULL, NULL);
> }
>
> /**
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 06f2c857de64..d68dd7f63923 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -539,12 +539,13 @@ static void iomap_readfolio_complete(const struct iomap_iter *iter,
> }
>
> int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops,
> - const struct iomap_read_ops *read_ops)
> + const struct iomap_read_ops *read_ops, void *private)
> {
> struct iomap_iter iter = {
> .inode = folio->mapping->host,
> .pos = folio_pos(folio),
> .len = folio_size(folio),
> + .private = private,
> };
> struct iomap_readfolio_ctx ctx = {
> .cur_folio = folio,
> @@ -591,6 +592,8 @@ static int iomap_readahead_iter(struct iomap_iter *iter,
> * @rac: Describes the pages to be read.
> * @ops: The operations vector for the filesystem.
> * @read_ops: Optional ops callers can pass in if they want custom handling.
> + * @private: If passed in, this will be usable by the caller in any
> + * read_ops callbacks.
> *
> * This function is for filesystems to call to implement their readahead
> * address_space operation.
> @@ -603,12 +606,13 @@ static int iomap_readahead_iter(struct iomap_iter *iter,
> * the filesystem to be reentered.
> */
> void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops,
> - const struct iomap_read_ops *read_ops)
> + const struct iomap_read_ops *read_ops, void *private)
> {
> struct iomap_iter iter = {
> .inode = rac->mapping->host,
> .pos = readahead_pos(rac),
> .len = readahead_length(rac),
> + .private = private,
> };
> struct iomap_readfolio_ctx ctx = {
> .rac = rac,
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index fb2150c0825a..5e71a3888e6d 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -742,14 +742,14 @@ xfs_vm_read_folio(
> struct file *unused,
> struct folio *folio)
> {
> - return iomap_read_folio(folio, &xfs_read_iomap_ops, NULL);
> + return iomap_read_folio(folio, &xfs_read_iomap_ops, NULL, NULL);
> }
>
> STATIC void
> xfs_vm_readahead(
> struct readahead_control *rac)
> {
> - iomap_readahead(rac, &xfs_read_iomap_ops, NULL);
> + iomap_readahead(rac, &xfs_read_iomap_ops, NULL, NULL);
> }
>
> static int
> diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
> index 96470daf4d3f..182bb473a82b 100644
> --- a/fs/zonefs/file.c
> +++ b/fs/zonefs/file.c
> @@ -112,12 +112,12 @@ static const struct iomap_ops zonefs_write_iomap_ops = {
>
> static int zonefs_read_folio(struct file *unused, struct folio *folio)
> {
> - return iomap_read_folio(folio, &zonefs_read_iomap_ops, NULL);
> + return iomap_read_folio(folio, &zonefs_read_iomap_ops, NULL, NULL);
> }
>
> static void zonefs_readahead(struct readahead_control *rac)
> {
> - iomap_readahead(rac, &zonefs_read_iomap_ops, NULL);
> + iomap_readahead(rac, &zonefs_read_iomap_ops, NULL, NULL);
> }
>
> /*
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index a7247439aeb5..9bc7900dd448 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -355,9 +355,9 @@ ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
> const struct iomap_ops *ops,
> const struct iomap_write_ops *write_ops, void *private);
> int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops,
> - const struct iomap_read_ops *read_ops);
> + const struct iomap_read_ops *read_ops, void *private);
> void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops,
> - const struct iomap_read_ops *read_ops);
> + const struct iomap_read_ops *read_ops, void *private);
> bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);
> struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len);
> bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
> --
> 2.47.3
>
>
