hulk inclusion category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/I93TU0 CVE: NA

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commit 9dc55f1389f9 ("iomap: add support for sub-pagesize buffered I/O without buffer heads") replace the per-block structure buffer_head with the per-page structure iomap_page. However, iomap_page can't track the dirty state of sub pages, which will cause performance issue since sub pages will be writeback even if they are not dirty.

For example, if block size is 4k and page size is 64k:

dd if=/dev/zero of=testfile bs=4k count=16 oflag=sync

With buffer_head implementation, the above dd cmd will writeback 4k in each round. However, with iomap_page implementation, the range of writeback in each round is from the start of the page to the end offset we just wrote.

Thus add support to track dirty state in iomap_page.

test environment: platform: arm64 pagesize: 64k blocksize: 4k

test case: dd if=/dev/zero of=/mnt/testfile bs=1M count=128 fio --ioengine=sync --rw=randwrite --iodepth=64 --name=test \ --filename=/mnt/testfile --bs=4k --fsync=1

The test result is: xfs with patch: WRITE: bw=4609KiB/s (4720kB/s) xfs without patch WRITE: bw=2714KiB/s (2780kB/s) ext4: WRITE: bw=3840KiB/s (3932kB/s)

Signed-off-by: Yu Kuai yukuai3@huawei.com --- Changes in v2: - remove changes to iomap_page_mkwrite_actor().

fs/iomap/buffered-io.c | 83 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 67 insertions(+), 16 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index d9092aa5c3fb..25448d5827d2 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -25,13 +25,13 @@

/* * Structure allocated for each page or THP when block size < page size - * to track sub-page uptodate status and I/O completions. + * to track sub-page uptodate and dirty status and I/O completions. */ struct iomap_page { atomic_t read_bytes_pending; atomic_t write_bytes_pending; - spinlock_t uptodate_lock; - unsigned long uptodate[]; + spinlock_t state_lock; + unsigned long state[]; };

static inline struct iomap_page *to_iomap_page(struct page *page) @@ -59,11 +59,13 @@ iomap_page_create(struct inode *inode, struct page *page) if (iop || nr_blocks <= 1) return iop;

- iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)), + iop = kzalloc(struct_size(iop, state, BITS_TO_LONGS(2 * nr_blocks)), GFP_NOFS | __GFP_NOFAIL); - spin_lock_init(&iop->uptodate_lock); + spin_lock_init(&iop->state_lock); if (PageUptodate(page)) - bitmap_fill(iop->uptodate, nr_blocks); + bitmap_set(iop->state, 0, nr_blocks); + if (PageDirty(page)) + bitmap_set(iop->state, nr_blocks, nr_blocks); attach_page_private(page, iop); return iop; } @@ -78,7 +80,7 @@ iomap_page_release(struct page *page) return; WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending)); WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending)); - WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) != + WARN_ON_ONCE(bitmap_full(iop->state, nr_blocks) != PageUptodate(page)); kfree(iop); } @@ -109,7 +111,7 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,

/* move forward for each leading block marked uptodate */ for (i = first; i <= last; i++) { - if (!test_bit(i, iop->uptodate)) + if (!test_bit(i, iop->state)) break; *pos += block_size; poff += block_size; @@ -119,7 +121,7 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,

/* truncate len if we find any trailing uptodate block(s) */ for ( ; i <= last; i++) { - if (test_bit(i, iop->uptodate)) { + if (test_bit(i, iop->state)) { plen -= (last - i + 1) * block_size; last = i - 1; break; @@ -143,6 +145,53 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop, *lenp = plen; }

+static void +iomap_set_range_dirty(struct page *page, unsigned int off, unsigned int len) +{ + struct inode *inode = page->mapping->host; + unsigned int nr_blocks = i_blocks_per_page(inode, page); + unsigned int first = off >> inode->i_blkbits; + unsigned int last = (off + len - 1) >> inode->i_blkbits; + unsigned long flags; + struct iomap_page *iop; + + if (PageError(page)) + return; + + if (len) + iomap_set_page_dirty(page); + + if (!page_has_private(page)) + return; + + iop = to_iomap_page(page); + spin_lock_irqsave(&iop->state_lock, flags); + bitmap_set(iop->state, first + nr_blocks, last - first + 1); + spin_unlock_irqrestore(&iop->state_lock, flags); +} + +static void +iomap_clear_range_dirty(struct page *page, unsigned int off, unsigned int len) +{ + struct inode *inode = page->mapping->host; + unsigned int nr_blocks = i_blocks_per_page(inode, page); + unsigned int first = off >> inode->i_blkbits; + unsigned int last = (off + len - 1) >> inode->i_blkbits; + unsigned long flags; + struct iomap_page *iop; + + if (PageError(page)) + return; + + if (!page_has_private(page)) + return; + + iop = to_iomap_page(page); + spin_lock_irqsave(&iop->state_lock, flags); + bitmap_clear(iop->state, first + nr_blocks, last - first + 1); + spin_unlock_irqrestore(&iop->state_lock, flags); +} + static void iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len) { @@ -152,11 +201,11 @@ iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len) unsigned last = (off + len - 1) >> inode->i_blkbits; unsigned long flags;

- spin_lock_irqsave(&iop->uptodate_lock, flags); - bitmap_set(iop->uptodate, first, last - first + 1); - if (bitmap_full(iop->uptodate, i_blocks_per_page(inode, page))) + spin_lock_irqsave(&iop->state_lock, flags); + bitmap_set(iop->state, first, last - first + 1); + if (bitmap_full(iop->state, i_blocks_per_page(inode, page))) SetPageUptodate(page); - spin_unlock_irqrestore(&iop->uptodate_lock, flags); + spin_unlock_irqrestore(&iop->state_lock, flags); }

static void @@ -451,7 +500,7 @@ iomap_is_partially_uptodate(struct page *page, unsigned long from,

if (iop) { for (i = first; i <= last; i++) - if (!test_bit(i, iop->uptodate)) + if (!test_bit(i, iop->state)) return 0; return 1; } @@ -708,7 +757,7 @@ static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len, if (unlikely(copied < len && !PageUptodate(page))) return 0; iomap_set_range_uptodate(page, offset_in_page(pos), len); - iomap_set_page_dirty(page); + iomap_set_range_dirty(page, offset_in_page(pos), len); return copied; }

@@ -1407,6 +1456,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, { struct iomap_page *iop = iomap_page_create(inode, page); struct iomap_ioend *ioend, *next; + unsigned int nr_blocks = i_blocks_per_page(inode, page); unsigned len = i_blocksize(inode); u64 file_offset; /* file offset of page */ int error = 0, count = 0, i; @@ -1422,7 +1472,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, for (i = 0, file_offset = page_offset(page); i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset; i++, file_offset += len) { - if (iop && !test_bit(i, iop->uptodate)) + if (iop && !test_bit(i + nr_blocks, iop->state)) continue;

error = wpc->ops->map_blocks(wpc, inode, file_offset); @@ -1465,6 +1515,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, } }

+ iomap_clear_range_dirty(page, 0, PAGE_SIZE); set_page_writeback(page); unlock_page(page);