From: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: david@fromorbit.com, djwong@kernel.org, hch@lst.de,
Keith Busch <kbusch@kernel.org>,
mcgrof@kernel.org, akpm@linux-foundation.org, brauner@kernel.org,
chandan.babu@oracle.com, gost.dev@samsung.com, hare@suse.de,
john.g.garry@oracle.com, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-xfs@vger.kernel.org, p.raghav@samsung.com,
ritesh.list@gmail.com, ziy@nvidia.com
Subject: Re: [RFC] iomap: use huge zero folio in iomap_dio_zero
Date: Thu, 16 May 2024 15:02:06 +0000 [thread overview]
Message-ID: <20240516150206.d64eezbj3waieef5@quentin> (raw)
In-Reply-To: <ZkT46AsZ3WghOArL@casper.infradead.org>
On Wed, May 15, 2024 at 07:03:20PM +0100, Matthew Wilcox wrote:
> On Wed, May 15, 2024 at 03:59:43PM +0000, Pankaj Raghav (Samsung) wrote:
> > static int __init iomap_init(void)
> > {
> > + void *addr = kzalloc(16 * PAGE_SIZE, GFP_KERNEL);
>
> Don't use XFS coding style outside XFS.
>
> kzalloc() does not guarantee page alignment much less alignment to
> a folio. It happens to work today, but that is an implementation
> artefact.
>
> > +
> > + if (!addr)
> > + return -ENOMEM;
> > +
> > + zero_fsb_folio = virt_to_folio(addr);
>
> We also don't guarantee that calling kzalloc() gives you a virtual
> address that can be converted to a folio. You need to allocate a folio
> to be sure that you get a folio.
>
> Of course, you don't actually need a folio. You don't need any of the
> folio metadata and can just use raw pages.
>
> > + /*
> > + * The zero folio used is 64k.
> > + */
> > + WARN_ON_ONCE(len > (16 * PAGE_SIZE));
>
> PAGE_SIZE is not necessarily 4KiB.
>
> > + bio = iomap_dio_alloc_bio(iter, dio, BIO_MAX_VECS,
> > + REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
>
> The point was that we now only need one biovec, not MAX.
>
Thanks for the comments. I think it all makes sense:
diff --git a/fs/internal.h b/fs/internal.h
index 7ca738904e34..e152b77a77e4 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -35,6 +35,14 @@ static inline void bdev_cache_init(void)
int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len,
get_block_t *get_block, const struct iomap *iomap);
+/*
+ * iomap/buffered-io.c
+ */
+
+#define ZERO_FSB_SIZE (65536)
+#define ZERO_FSB_ORDER (get_order(ZERO_FSB_SIZE))
+extern struct page *zero_fs_block;
+
/*
* char_dev.c
*/
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 4e8e41c8b3c0..36d2f7edd310 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -42,6 +42,7 @@ struct iomap_folio_state {
};
static struct bio_set iomap_ioend_bioset;
+struct page *zero_fs_block;
static inline bool ifs_is_fully_uptodate(struct folio *folio,
struct iomap_folio_state *ifs)
@@ -1985,8 +1986,13 @@ iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
}
EXPORT_SYMBOL_GPL(iomap_writepages);
+
static int __init iomap_init(void)
{
+ zero_fs_block = alloc_pages(GFP_KERNEL | __GFP_ZERO, ZERO_FSB_ORDER);
+ if (!zero_fs_block)
+ return -ENOMEM;
+
return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
offsetof(struct iomap_ioend, io_bio),
BIOSET_NEED_BVECS);
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index f3b43d223a46..50c2bca8a347 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -236,17 +236,22 @@ static void 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;
+ /*
+ * Max block size supported is 64k
+ */
+ WARN_ON_ONCE(len > ZERO_FSB_SIZE);
+
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);
+
bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
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_fs_block, len, 0);
iomap_dio_submit_bio(iter, dio, bio, pos);
}
next prev parent reply other threads:[~2024-05-16 15:02 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-03 9:53 [PATCH v5 00/11] enable bs > ps in XFS Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 01/11] readahead: rework loop in page_cache_ra_unbounded() Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 02/11] fs: Allow fine-grained control of folio sizes Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 03/11] filemap: allocate mapping_min_order folios in the page cache Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 04/11] readahead: allocate folios with mapping_min_order in readahead Luis Chamberlain
2024-05-03 14:32 ` Hannes Reinecke
2024-05-03 9:53 ` [PATCH v5 05/11] mm: split a folio in minimum folio order chunks Luis Chamberlain
2024-05-03 14:53 ` Zi Yan
2024-05-15 15:32 ` Matthew Wilcox
2024-05-16 14:56 ` Pankaj Raghav (Samsung)
2024-05-03 9:53 ` [PATCH v5 06/11] filemap: cap PTE range to be created to allowed zero fill in folio_map_range() Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Luis Chamberlain
2024-05-07 14:58 ` [RFC] iomap: use huge zero folio in iomap_dio_zero Pankaj Raghav (Samsung)
2024-05-07 15:11 ` Zi Yan
2024-05-07 16:11 ` Christoph Hellwig
2024-05-08 11:39 ` Pankaj Raghav (Samsung)
2024-05-08 11:43 ` Christoph Hellwig
2024-05-09 12:31 ` Pankaj Raghav (Samsung)
2024-05-09 12:46 ` Christoph Hellwig
2024-05-09 12:55 ` Pankaj Raghav (Samsung)
2024-05-09 12:58 ` Christoph Hellwig
2024-05-09 14:32 ` Darrick J. Wong
2024-05-09 15:05 ` Christoph Hellwig
2024-05-09 15:08 ` Darrick J. Wong
2024-05-09 15:09 ` Christoph Hellwig
2024-05-15 0:50 ` Matthew Wilcox
2024-05-15 2:34 ` Keith Busch
2024-05-15 4:04 ` Matthew Wilcox
2024-05-15 15:59 ` Pankaj Raghav (Samsung)
2024-05-15 18:03 ` Matthew Wilcox
2024-05-16 15:02 ` Pankaj Raghav (Samsung) [this message]
2024-05-17 12:36 ` Hannes Reinecke
2024-05-17 12:56 ` Hannes Reinecke
2024-05-17 13:30 ` Matthew Wilcox
2024-05-15 11:48 ` Christoph Hellwig
2024-05-07 16:00 ` [PATCH v5 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Matthew Wilcox
2024-05-07 16:10 ` Christoph Hellwig
2024-05-07 16:11 ` Matthew Wilcox
2024-05-07 16:13 ` Christoph Hellwig
2024-05-08 4:24 ` Matthew Wilcox
2024-05-08 11:22 ` Pankaj Raghav (Samsung)
2024-05-08 11:36 ` Christoph Hellwig
2024-05-08 11:20 ` Pankaj Raghav (Samsung)
2024-05-03 9:53 ` [PATCH v5 08/11] xfs: use kvmalloc for xattr buffers Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 09/11] xfs: expose block size in stat Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count() Luis Chamberlain
2024-05-07 8:40 ` John Garry
2024-05-07 21:13 ` Darrick J. Wong
2024-05-08 11:28 ` Pankaj Raghav (Samsung)
2024-05-03 9:53 ` [PATCH v5 11/11] xfs: enable block size larger than page size support Luis Chamberlain
2024-05-07 0:05 ` Dave Chinner
-- strict thread matches above, loose matches on Subject: below --
2024-05-07 18:38 [RFC] iomap: use huge zero folio in iomap_dio_zero Ritesh Harjani
2024-05-08 11:42 ` Christoph Hellwig
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