| Message ID | 20240704112320.82104-7-kernel@pankajraghav.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | enable bs > ps in XFS | expand |
On 7/4/24 13:23, Pankaj Raghav (Samsung) wrote: > From: Pankaj Raghav <p.raghav@samsung.com> > > 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@samsung.com> > --- > 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
On Thu, Jul 04, 2024 at 05:37:32PM +0200, Hannes Reinecke wrote: > On 7/4/24 13:23, Pankaj Raghav (Samsung) wrote: > > From: Pankaj Raghav <p.raghav@samsung.com> > > > > 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@samsung.com> > > --- > > 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? Please, no. We need to stop feature creeping this patchset and bring it to a close. If changing code entirely unrelated to this patchset is desired, please do it as a separate independent set of patches. -Dave.
On 7/5/24 00:13, Dave Chinner wrote: > On Thu, Jul 04, 2024 at 05:37:32PM +0200, Hannes Reinecke wrote: >> On 7/4/24 13:23, Pankaj Raghav (Samsung) wrote: >>> From: Pankaj Raghav <p.raghav@samsung.com> >>> >>> 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@samsung.com> >>> --- >>> 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? > > Please, no. > > We need to stop feature creeping this patchset and bring it to a > close. If changing code entirely unrelated to this patchset is > desired, please do it as a separate independent set of patches. > Agree; it was a suggestion only. Pankaj, you can add my: Reviewed-by: Hannes Reinecke <hare@suse.de> Cheers, Hannes
> > > > > > 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? > > > > Please, no. > > > > We need to stop feature creeping this patchset and bring it to a > > close. If changing code entirely unrelated to this patchset is > > desired, please do it as a separate independent set of patches. > > > Agree; it was a suggestion only. I was going to say the same thing that Dave said as well as we are almost there with this series :) But I will add your suggestion in my TODO. It would be good to have some common infra to avoid allocating larger zero pages all over the place. > > Pankaj, you can add my: > > Reviewed-by: Hannes Reinecke <hare@suse.de> Thanks Hannes.
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; + 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);