[PATCH v4 13/36] iomap: Support arbitrarily many blocks per page

Matthew Wilcox
2020-05-15T13:41:42Z

Size the uptodate array dynamically. Now that this array is protected
by a spinlock, we can use bitmap functions to set the bits in this array
instead of a loop around set_bit().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 27 +++++++++------------------
1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 4bc37bf8d057..4a79061073eb 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -22,14 +22,14 @@
#include "../internal.h"

/*
- * Structure allocated for each page when block size < PAGE_SIZE to track
+ * Structure allocated for each page when block size < page size to track
* sub-page uptodate status and I/O completions.
*/
struct iomap_page {
atomic_t read_count;
atomic_t write_count;
spinlock_t uptodate_lock;
- DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
+ unsigned long uptodate[];
};

static inline struct iomap_page *to_iomap_page(struct page *page)
@@ -45,15 +45,14 @@ static struct iomap_page *
iomap_page_create(struct inode *inode, struct page *page)
{
struct iomap_page *iop = to_iomap_page(page);
+ unsigned int nr_blocks = i_blocks_per_page(inode, page);

- if (iop || i_blocks_per_page(inode, page) <= 1)
+ if (iop || nr_blocks <= 1)
return iop;

- iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
- atomic_set(&iop->read_count, 0);
- atomic_set(&iop->write_count, 0);
+ iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
+ GFP_NOFS | __GFP_NOFAIL);
spin_lock_init(&iop->uptodate_lock);
- bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);

/*
* migrate_page_move_mapping() assumes that pages with private data have
@@ -146,20 +145,12 @@ iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
struct iomap_page *iop = to_iomap_page(page);
struct inode *inode = page->mapping->host;
unsigned first = off >> inode->i_blkbits;
- unsigned last = (off + len - 1) >> inode->i_blkbits;
- bool uptodate = true;
+ unsigned count = len >> inode->i_blkbits;
unsigned long flags;
- unsigned int i;

spin_lock_irqsave(&iop->uptodate_lock, flags);
- for (i = 0; i < i_blocks_per_page(inode, page); i++) {
- if (i >= first && i <= last)
- set_bit(i, iop->uptodate);
- else if (!test_bit(i, iop->uptodate))
- uptodate = false;
- }
-
- if (uptodate)
+ bitmap_set(iop->uptodate, first, count);
+ if (bitmap_full(iop->uptodate, i_blocks_per_page(inode, page)))
SetPageUptodate(page);
spin_unlock_irqrestore(&iop->uptodate_lock, flags);
}
--
2.26.2