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btrfs: refactor btrfs_invalidatepage() for subpage support 

This patch will refactor btrfs_invalidatepage() for the incoming subpage
support.

The involved modifications are:

- Use while() loop instead of "goto again;"
- Use single variable to determine whether to delete extent states
  Each branch will also have comments why we can or cannot delete the
  extent states
- Do qgroup free and extent states deletion per-loop
  Current code can only work for PAGE_SIZE == sectorsize case.

This refactor also makes it clear what we do for different sectors:

- Sectors without ordered extent
  We're completely safe to remove all extent states for the sector(s)

- Sectors with ordered extent, but no Private2 bit
  This means the endio has already been executed, we can't remove all
  extent states for the sector(s).

- Sectors with ordere extent, still has Private2 bit
  This means we need to decrease the ordered extent accounting.
  And then it comes to two different variants:

  * We have finished and removed the ordered extent
    Then it's the same as "sectors without ordered extent"
  * We didn't finished the ordered extent
    We can remove some extent states, but not all.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2021-04-06 19:54:53 +08:00 committed by David Sterba
parent c095f3333f
commit 3b8358407a
1 changed files with 99 additions and 76 deletions
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175
fs/btrfs/inode.c
View File

@ -8318,15 +8318,11 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset,
{
struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
struct extent_io_tree *tree = &inode->io_tree;
struct btrfs_ordered_extent *ordered;
struct extent_state *cached_state = NULL;
u64 page_start = page_offset(page);
u64 page_end = page_start + PAGE_SIZE - 1;
u64 start;
u64 end;
u64 cur;
int inode_evicting = inode->vfs_inode.i_state & I_FREEING;
bool found_ordered = false;
bool completed_ordered = false;
/*
* We have page locked so no new ordered extent can be created on this
@ -8350,93 +8346,120 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset,
if (!inode_evicting)
lock_extent_bits(tree, page_start, page_end, &cached_state);
start = page_start;
again:
ordered = btrfs_lookup_ordered_range(inode, start, page_end - start + 1);
if (ordered) {
found_ordered = true;
end = min(page_end,
ordered->file_offset + ordered->num_bytes - 1);
cur = page_start;
while (cur < page_end) {
struct btrfs_ordered_extent *ordered;
bool delete_states;
u64 range_end;
ordered = btrfs_lookup_first_ordered_range(inode, cur,
page_end + 1 - cur);
if (!ordered) {
range_end = page_end;
/*
* No ordered extent covering this range, we are safe
* to delete all extent states in the range.
*/
delete_states = true;
goto next;
}
if (ordered->file_offset > cur) {
/*
* There is a range between [cur, oe->file_offset) not
* covered by any ordered extent.
* We are safe to delete all extent states, and handle
* the ordered extent in the next iteration.
*/
range_end = ordered->file_offset - 1;
delete_states = true;
goto next;
}
range_end = min(ordered->file_offset + ordered->num_bytes - 1,
page_end);
if (!PagePrivate2(page)) {
/*
* If Private2 is cleared, it means endio has already
* been executed for the range.
* We can't delete the extent states as
* btrfs_finish_ordered_io() may still use some of them.
*/
delete_states = false;
goto next;
}
ClearPagePrivate2(page);
/*
* IO on this page will never be started, so we need to account
* for any ordered extents now. Don't clear EXTENT_DELALLOC_NEW
* here, must leave that up for the ordered extent completion.
*
* This will also unlock the range for incoming
* btrfs_finish_ordered_io().
*/
if (!inode_evicting)
clear_extent_bit(tree, start, end,
clear_extent_bit(tree, cur, range_end,
EXTENT_DELALLOC |
EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
EXTENT_DEFRAG, 1, 0, &cached_state);
spin_lock_irq(&inode->ordered_tree.lock);
set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
ordered->truncated_len = min(ordered->truncated_len,
cur - ordered->file_offset);
spin_unlock_irq(&inode->ordered_tree.lock);
if (btrfs_dec_test_ordered_pending(inode, &ordered,
cur, range_end + 1 - cur, 1)) {
btrfs_finish_ordered_io(ordered);
/*
* The ordered extent has finished, now we're again
* safe to delete all extent states of the range.
*/
delete_states = true;
} else {
/*
* btrfs_finish_ordered_io() will get executed by endio
* of other pages, thus we can't delete extent states
* anymore
*/
delete_states = false;
}
next:
if (ordered)
btrfs_put_ordered_extent(ordered);
/*
* A page with Private2 bit means no bio has been submitted
* covering the page, thus we have to manually do the ordered
* extent accounting.
* Qgroup reserved space handler
* Sector(s) here will be either:
*
* For page without Private2, the ordered extent accounting is
* done in its endio function of the submitted bio.
* 1) Already written to disk or bio already finished
* Then its QGROUP_RESERVED bit in io_tree is already cleared.
* Qgroup will be handled by its qgroup_record then.
* btrfs_qgroup_free_data() call will do nothing here.
*
* 2) Not written to disk yet
* Then btrfs_qgroup_free_data() call will clear the
* QGROUP_RESERVED bit of its io_tree, and free the qgroup
* reserved data space.
* Since the IO will never happen for this page.
*/
if (TestClearPagePrivate2(page)) {
spin_lock_irq(&inode->ordered_tree.lock);
set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
ordered->truncated_len = min(ordered->truncated_len,
start - ordered->file_offset);
spin_unlock_irq(&inode->ordered_tree.lock);
if (btrfs_dec_test_ordered_pending(inode, &ordered,
start,
end - start + 1, 1)) {
btrfs_finish_ordered_io(ordered);
completed_ordered = true;
}
}
btrfs_put_ordered_extent(ordered);
btrfs_qgroup_free_data(inode, NULL, cur, range_end + 1 - cur);
if (!inode_evicting) {
cached_state = NULL;
lock_extent_bits(tree, start, end,
&cached_state);
}
start = end + 1;
if (start < page_end)
goto again;
}
/*
* Qgroup reserved space handler
* Page here will be either
* 1) Already written to disk or ordered extent already submitted
* Then its QGROUP_RESERVED bit in io_tree is already cleaned.
* Qgroup will be handled by its qgroup_record then.
* btrfs_qgroup_free_data() call will do nothing here.
*
* 2) Not written to disk yet
* Then btrfs_qgroup_free_data() call will clear the QGROUP_RESERVED
* bit of its io_tree, and free the qgroup reserved data space.
* Since the IO will never happen for this page.
*/
btrfs_qgroup_free_data(inode, NULL, page_start, PAGE_SIZE);
if (!inode_evicting) {
bool delete = true;
/*
* If there's an ordered extent for this range and we have not
* finished it ourselves, we must leave EXTENT_DELALLOC_NEW set
* in the range for the ordered extent completion. We must also
* not delete the range, otherwise we would lose that bit (and
* any other bits set in the range). Make sure EXTENT_UPTODATE
* is cleared if we don't delete, otherwise it can lead to
* corruptions if the i_size is extented later.
*/
if (found_ordered && !completed_ordered)
delete = false;
clear_extent_bit(tree, page_start, page_end, EXTENT_LOCKED |
clear_extent_bit(tree, cur, range_end, EXTENT_LOCKED |
EXTENT_DELALLOC | EXTENT_UPTODATE |
EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 1,
delete, &cached_state);
__btrfs_releasepage(page, GFP_NOFS);
delete_states, &cached_state);
}
cur = range_end + 1;
}
/*
* We have iterated through all ordered extents of the page, the page
* should not have Private2 anymore, or the above iteration does
* something wrong.
*/
ASSERT(!PagePrivate2(page));
if (!inode_evicting)
__btrfs_releasepage(page, GFP_NOFS);
ClearPageChecked(page);
clear_page_extent_mapped(page);
}