[PATCH 6.18 155/396] iomap: add a separate bio_set for iomap_split_ioend

Greg Kroah-Hartman <[email protected]>
Newsgroups org.kernel.vger.stable,dev.linux.lists.patches
Message-ID <[email protected]>
6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Hellwig <[email protected]>

[ Upstream commit c679ce3be6cb63763d68ab9b5d9d73ddc0a40762 ]

iomap_split_ioend can split bios that already come from
iomap_ioend_bioset and thus deadlock when the bioset is exhausted.

Add a separate bio_set to avoid this deadlock.

Christian Brauner <[email protected]> says:
Mark iomap_ioend_split_bioset static as it is only used in ioend.c,
fixing the sparse warning reported by the kernel test robot.

Fixes: 5fcbd555d483 ("iomap: split bios to zone append limits in the submission handlers")
Signed-off-by: Christoph Hellwig <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Christian Brauner (Amutable) <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 fs/iomap/ioend.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/fs/iomap/ioend.c b/fs/iomap/ioend.c
index 6c75fbf4d5af4..2a86b05c88efc 100644
--- a/fs/iomap/ioend.c
+++ b/fs/iomap/ioend.c
@@ -11,6 +11,7 @@
 
 struct bio_set iomap_ioend_bioset;
 EXPORT_SYMBOL_GPL(iomap_ioend_bioset);
+static struct bio_set iomap_ioend_split_bioset;
 
 struct iomap_ioend *iomap_init_ioend(struct inode *inode,
 		struct bio *bio, loff_t file_offset, u16 ioend_flags)
@@ -409,7 +410,8 @@ struct iomap_ioend *iomap_split_ioend(struct iomap_ioend *ioend,
 	sector_offset = ALIGN_DOWN(sector_offset << SECTOR_SHIFT,
 			i_blocksize(ioend->io_inode)) >> SECTOR_SHIFT;
 
-	split = bio_split(bio, sector_offset, GFP_NOFS, &iomap_ioend_bioset);
+	split = bio_split(bio, sector_offset, GFP_NOFS,
+			&iomap_ioend_split_bioset);
 	if (IS_ERR(split))
 		return ERR_CAST(split);
 	split->bi_private = bio->bi_private;
@@ -432,8 +434,23 @@ EXPORT_SYMBOL_GPL(iomap_split_ioend);
 
 static int __init iomap_ioend_init(void)
 {
-	return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
+	const unsigned int nr_mempool_entries = 4 * (PAGE_SIZE / SECTOR_SIZE);
+	int error;
+
+	error = bioset_init(&iomap_ioend_bioset, nr_mempool_entries,
 			   offsetof(struct iomap_ioend, io_bio),
 			   BIOSET_NEED_BVECS);
+	if (error)
+		return error;
+	error = bioset_init(&iomap_ioend_split_bioset, nr_mempool_entries,
+			   offsetof(struct iomap_ioend, io_bio),
+			   BIOSET_NEED_BVECS);
+	if (error)
+		goto out_exit_ioend_bioset;
+	return 0;
+
+out_exit_ioend_bioset:
+	bioset_exit(&iomap_ioend_bioset);
+	return error;
 }
 fs_initcall(iomap_ioend_init);
-- 
2.53.0
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