On 7/4/24 13:23, Pankaj Raghav (Samsung) wrote:
From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
iomap_dio_zero() will pad a fs block with zeroes if the direct IO size
< fs block size. iomap_dio_zero() has an implicit assumption that fs block
size < page_size. This is true for most filesystems at the moment.
If the block size > page size, this will send the contents of the page
next to zero page(as len > PAGE_SIZE) to the underlying block device,
causing FS corruption.
iomap is a generic infrastructure and it should not make any assumptions
about the fs block size and the page size of the system.
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
fs/iomap/buffered-io.c | 4 ++--
fs/iomap/direct-io.c | 45 ++++++++++++++++++++++++++++++++++++------
2 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f420c53d86acc..d745f718bcde8 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -2007,10 +2007,10 @@ iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
}
EXPORT_SYMBOL_GPL(iomap_writepages);
-static int __init iomap_init(void)
+static int __init iomap_buffered_init(void)
{
return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
offsetof(struct iomap_ioend, io_bio),
BIOSET_NEED_BVECS);
}
-fs_initcall(iomap_init);
+fs_initcall(iomap_buffered_init);
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index f3b43d223a46e..c02b266bba525 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -11,6 +11,7 @@
#include <linux/iomap.h>
#include <linux/backing-dev.h>
#include <linux/uio.h>
+#include <linux/set_memory.h>
#include <linux/task_io_accounting_ops.h>
#include "trace.h"
@@ -27,6 +28,13 @@
#define IOMAP_DIO_WRITE (1U << 30)
#define IOMAP_DIO_DIRTY (1U << 31)
+/*
+ * Used for sub block zeroing in iomap_dio_zero()
+ */
+#define IOMAP_ZERO_PAGE_SIZE (SZ_64K)
+#define IOMAP_ZERO_PAGE_ORDER (get_order(IOMAP_ZERO_PAGE_SIZE))
+static struct page *zero_page;
+
There are other users of ZERO_PAGE, most notably in fs/direct-io.c and
block/blk-lib.c. Any chance to make this available to them?
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
