From: Joanne Koong <joannelkoong@gmail.com>
Date: Fri, 26 Sep 2025 00:25:58 +0000 (-0700)
Subject: iomap: store read/readahead bio generically
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d1f9893fcd846dd912243046e66470c06b505cfa;p=thirdparty%2Flinux.git

iomap: store read/readahead bio generically

Store the iomap_readpage_ctx bio generically as a "void *read_ctx".
This makes the read/readahead interface more generic, which allows it to
be used by filesystems that may not be block-based and may not have
CONFIG_BLOCK set.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f8b985bb5a6b..b06b532033ad 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -363,13 +363,13 @@ static void iomap_read_end_io(struct bio *bio)
 struct iomap_readpage_ctx {
 	struct folio		*cur_folio;
 	bool			cur_folio_in_bio;
-	struct bio		*bio;
+	void			*read_ctx;
 	struct readahead_control *rac;
 };
 
 static void iomap_bio_submit_read(struct iomap_readpage_ctx *ctx)
 {
-	struct bio *bio = ctx->bio;
+	struct bio *bio = ctx->read_ctx;
 
 	if (bio)
 		submit_bio(bio);
@@ -384,6 +384,7 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter,
 	size_t poff = offset_in_folio(folio, pos);
 	loff_t length = iomap_length(iter);
 	sector_t sector;
+	struct bio *bio = ctx->read_ctx;
 
 	ctx->cur_folio_in_bio = true;
 	if (ifs) {
@@ -393,9 +394,8 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter,
 	}
 
 	sector = iomap_sector(iomap, pos);
-	if (!ctx->bio ||
-	    bio_end_sector(ctx->bio) != sector ||
-	    !bio_add_folio(ctx->bio, folio, plen, poff)) {
+	if (!bio || bio_end_sector(bio) != sector ||
+	    !bio_add_folio(bio, folio, plen, poff)) {
 		gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
 		gfp_t orig_gfp = gfp;
 		unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
@@ -404,22 +404,21 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter,
 
 		if (ctx->rac) /* same as readahead_gfp_mask */
 			gfp |= __GFP_NORETRY | __GFP_NOWARN;
-		ctx->bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs),
-				     REQ_OP_READ, gfp);
+		bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs), REQ_OP_READ,
+				     gfp);
 		/*
 		 * If the bio_alloc fails, try it again for a single page to
 		 * avoid having to deal with partial page reads.  This emulates
 		 * what do_mpage_read_folio does.
 		 */
-		if (!ctx->bio) {
-			ctx->bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ,
-					     orig_gfp);
-		}
+		if (!bio)
+			bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp);
 		if (ctx->rac)
-			ctx->bio->bi_opf |= REQ_RAHEAD;
-		ctx->bio->bi_iter.bi_sector = sector;
-		ctx->bio->bi_end_io = iomap_read_end_io;
-		bio_add_folio_nofail(ctx->bio, folio, plen, poff);
+			bio->bi_opf |= REQ_RAHEAD;
+		bio->bi_iter.bi_sector = sector;
+		bio->bi_end_io = iomap_read_end_io;
+		bio_add_folio_nofail(bio, folio, plen, poff);
+		ctx->read_ctx = bio;
 	}
 }