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btrfs: defrag: replace hard coded PAGE_SIZE with sectorsize

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When testing subpage defrag support, I always find some strange inode
nbytes error, after a lot of debugging, it turns out that
defrag_lookup_extent() is using PAGE_SIZE as size for
lookup_extent_mapping().

Since lookup_extent_mapping() is calling __lookup_extent_mapping() with
@strict == 1, this means any extent map smaller than one page will be
ignored, prevent subpage defrag to grab a correct extent map.

There are quite some PAGE_SIZE usage in ioctl.c, but most of them are
correct usages, and can be one of the following cases:

- ioctl structure size check
  We want ioctl structure to be contained inside one page.

- real page operations

The remaining cases in defrag_lookup_extent() and
check_defrag_in_cache() will be addressed in this patch.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2021-08-06 16:12:34 +08:00 committed by David Sterba
parent cae7968680
commit 76068cae63
1 changed files with 6 additions and 5 deletions
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11
fs/btrfs/ioctl.c
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@ -997,10 +997,11 @@ static int check_defrag_in_cache(struct inode *inode, u64 offset, u32 thresh)
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct extent_map *em = NULL;
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
const u32 sectorsize = btrfs_sb(inode->i_sb)->sectorsize;
u64 end;
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, offset, PAGE_SIZE);
em = lookup_extent_mapping(em_tree, offset, sectorsize);
read_unlock(&em_tree->lock);
if (em) {
@ -1090,23 +1091,23 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start)
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct extent_map *em;
u64 len = PAGE_SIZE;
const u32 sectorsize = BTRFS_I(inode)->root->fs_info->sectorsize;
/*
* hopefully we have this extent in the tree already, try without
* the full extent lock
*/
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, start, len);
em = lookup_extent_mapping(em_tree, start, sectorsize);
read_unlock(&em_tree->lock);
if (!em) {
struct extent_state *cached = NULL;
u64 end = start + len - 1;
u64 end = start + sectorsize - 1;
/* get the big lock and read metadata off disk */
lock_extent_bits(io_tree, start, end, &cached);
em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len);
em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, sectorsize);
unlock_extent_cached(io_tree, start, end, &cached);
if (IS_ERR(em))