From: Pankaj Raghav <p.raghav@xxxxxxxxxxx> [ Upstream commit 10553a91652d995274da63fc317470f703765081 ] 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> Link: https://lore.kernel.org/r/20240822135018.1931258-7-kernel@xxxxxxxxxxxxxxxx Reviewed-by: Hannes Reinecke <hare@xxxxxxx> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx> Reviewed-by: Daniel Gomez <da.gomez@xxxxxxxxxxx> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 d465589902790..d505636035af3 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1992,10 +1992,10 @@ 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; + struct iomap_dio { struct kiocb *iocb; const struct iomap_dio_ops *dops; @@ -232,13 +240,20 @@ void iomap_dio_bio_end_io(struct bio *bio) } EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io); -static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, +static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, loff_t pos, unsigned len) { struct inode *inode = file_inode(dio->iocb->ki_filp); - struct page *page = ZERO_PAGE(0); struct bio *bio; + if (!len) + return 0; + /* + * Max block size supported is 64k + */ + if (WARN_ON_ONCE(len > IOMAP_ZERO_PAGE_SIZE)) + return -EINVAL; + bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE); fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, GFP_KERNEL); @@ -246,8 +261,9 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, bio->bi_private = dio; bio->bi_end_io = iomap_dio_bio_end_io; - __bio_add_page(bio, page, len, 0); + __bio_add_page(bio, zero_page, len, 0); iomap_dio_submit_bio(iter, dio, bio, pos); + return 0; } /* @@ -356,8 +372,10 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, if (need_zeroout) { /* zero out from the start of the block to the write offset */ pad = pos & (fs_block_size - 1); - if (pad) - iomap_dio_zero(iter, dio, pos - pad, pad); + + ret = iomap_dio_zero(iter, dio, pos - pad, pad); + if (ret) + goto out; } /* @@ -431,7 +449,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, /* zero out from the end of the write to the end of the block */ pad = pos & (fs_block_size - 1); if (pad) - iomap_dio_zero(iter, dio, pos, fs_block_size - pad); + ret = iomap_dio_zero(iter, dio, pos, + fs_block_size - pad); } out: /* Undo iter limitation to current extent */ @@ -753,3 +772,17 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, return iomap_dio_complete(dio); } EXPORT_SYMBOL_GPL(iomap_dio_rw); + +static int __init iomap_dio_init(void) +{ + zero_page = alloc_pages(GFP_KERNEL | __GFP_ZERO, + IOMAP_ZERO_PAGE_ORDER); + + if (!zero_page) + return -ENOMEM; + + set_memory_ro((unsigned long)page_address(zero_page), + 1U << IOMAP_ZERO_PAGE_ORDER); + return 0; +} +fs_initcall(iomap_dio_init); -- 2.43.0
