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btrfs: subpage: make extent_write_locked_range() compatible

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There are two sites are not subpage compatible yet for
extent_write_locked_range():

- How @nr_pages are calculated
  For subpage we can have the following range with 64K page size:

  0   32K  64K   96K 128K
  |   |////|/////|   |

  In that case, although 96K - 32K == 64K, thus it looks like one page
  is enough, but the range spans two pages, not one.

  Fix it by doing proper round_up() and round_down() to calculate
  @nr_pages.

  Also add some extra ASSERT()s to ensure the range passed in is already
  aligned.

- How the page end is calculated
  Currently we just use cur + PAGE_SIZE - 1 to calculate the page end.

  Which can't handle the above range layout, and will trigger ASSERT()
  in btrfs_writepage_endio_finish_ordered(), as the range is no longer
  covered by the page range.

  Fix it by taking page end into consideration.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2021-09-27 15:22:02 +08:00 committed by David Sterba
parent 741ec653ab
commit 66448b9d5b
1 changed files with 11 additions and 4 deletions
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15
fs/btrfs/extent_io.c
View file

@ -5086,15 +5086,14 @@ int extent_write_locked_range(struct inode *inode, u64 start, u64 end)
struct address_space *mapping = inode->i_mapping;
struct page *page;
u64 cur = start;
unsigned long nr_pages = (end - start + PAGE_SIZE) >>
PAGE_SHIFT;
unsigned long nr_pages;
const u32 sectorsize = btrfs_sb(inode->i_sb)->sectorsize;
struct extent_page_data epd = {
.bio_ctrl = { 0 },
.extent_locked = 1,
.sync_io = 1,
};
struct writeback_control wbc_writepages = {
.nr_to_write = nr_pages * 2,
.sync_mode = WB_SYNC_ALL,
.range_start = start,
.range_end = end + 1,
@ -5103,14 +5102,22 @@ int extent_write_locked_range(struct inode *inode, u64 start, u64 end)
.no_cgroup_owner = 1,
};
ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(end + 1, sectorsize));
nr_pages = (round_up(end, PAGE_SIZE) - round_down(start, PAGE_SIZE)) >>
PAGE_SHIFT;
wbc_writepages.nr_to_write = nr_pages * 2;
wbc_attach_fdatawrite_inode(&wbc_writepages, inode);
while (cur <= end) {
u64 cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end);
page = find_get_page(mapping, cur >> PAGE_SHIFT);
/*
* All pages in the range are locked since
* btrfs_run_delalloc_range(), thus there is no way to clear
* the page dirty flag.
*/
ASSERT(PageLocked(page));
ASSERT(PageDirty(page));
clear_page_dirty_for_io(page);
ret = __extent_writepage(page, &wbc_writepages, &epd);
@ -5120,7 +5127,7 @@ int extent_write_locked_range(struct inode *inode, u64 start, u64 end)
first_error = ret;
}
put_page(page);
cur += PAGE_SIZE;
cur = cur_end + 1;
}
if (!found_error)