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btrfs: factor out metadata subpage detection into a dedicated helper

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Currently we have only one btrfs_is_subpage() to cover both data and
metadata.

But there is a special case for metadata:

- dummy extent buffer, sector size < PAGE_SIZE and node size >= PAGE_SIZE

In such case, btrfs_is_subpage() will return true for extent buffer
folio.

But that is not correct, and that's exactly why we have some open-coded
checks for functions like set_extent_buffer_uptodate() and
clear_extent_buffer_uptodate().

Just extract the metadata specific checks into a helper, and replace
those call sites.

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 2025-01-28 15:26:42 +10:30 committed by David Sterba
parent 619611e87f
commit f64e818153
3 changed files with 34 additions and 17 deletions
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28
fs/btrfs/extent_io.c
View File

@ -836,7 +836,7 @@ static int attach_extent_buffer_folio(struct extent_buffer *eb,
if (folio->mapping)
lockdep_assert_held(&folio->mapping->i_private_lock);
if (fs_info->nodesize >= PAGE_SIZE) {
if (!btrfs_meta_is_subpage(fs_info)) {
if (!folio_test_private(folio))
folio_attach_private(folio, eb);
else
@ -1797,7 +1797,7 @@ static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
wbc_init_bio(wbc, &bbio->bio);
bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
bbio->file_offset = eb->start;
if (fs_info->nodesize < PAGE_SIZE) {
if (btrfs_meta_is_subpage(fs_info)) {
struct folio *folio = eb->folios[0];
bool ret;
@ -1939,7 +1939,7 @@ static int submit_eb_page(struct folio *folio, struct btrfs_eb_write_context *ct
if (!folio_test_private(folio))
return 0;
if (folio_to_fs_info(folio)->nodesize < PAGE_SIZE)
if (btrfs_meta_is_subpage(folio_to_fs_info(folio)))
return submit_eb_subpage(folio, wbc);
spin_lock(&mapping->i_private_lock);
@ -2596,7 +2596,7 @@ static void detach_extent_buffer_folio(const struct extent_buffer *eb, struct fo
return;
}
if (fs_info->nodesize >= PAGE_SIZE) {
if (!btrfs_meta_is_subpage(fs_info)) {
/*
* We do this since we'll remove the pages after we've
* removed the eb from the radix tree, so we could race
@ -2900,7 +2900,7 @@ static struct extent_buffer *grab_extent_buffer(struct btrfs_fs_info *fs_info,
* don't try to insert two ebs for the same bytenr. So here we always
* return NULL and just continue.
*/
if (fs_info->nodesize < PAGE_SIZE)
if (btrfs_meta_is_subpage(fs_info))
return NULL;
/* Page not yet attached to an extent buffer */
@ -3003,7 +3003,7 @@ static int attach_eb_folio_to_filemap(struct extent_buffer *eb, int i,
finish:
spin_lock(&mapping->i_private_lock);
if (existing_folio && fs_info->nodesize < PAGE_SIZE) {
if (existing_folio && btrfs_meta_is_subpage(fs_info)) {
/* We're going to reuse the existing page, can drop our folio now. */
__free_page(folio_page(eb->folios[i], 0));
eb->folios[i] = existing_folio;
@ -3094,7 +3094,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
* The memory will be freed by attach_extent_buffer_page() or freed
* manually if we exit earlier.
*/
if (fs_info->nodesize < PAGE_SIZE) {
if (btrfs_meta_is_subpage(fs_info)) {
prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA);
if (IS_ERR(prealloc)) {
ret = PTR_ERR(prealloc);
@ -3395,7 +3395,7 @@ void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans,
percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len,
fs_info->dirty_metadata_batch);
if (eb->fs_info->nodesize < PAGE_SIZE)
if (btrfs_meta_is_subpage(fs_info))
return clear_subpage_extent_buffer_dirty(eb);
num_folios = num_extent_folios(eb);
@ -3426,7 +3426,7 @@ void set_extent_buffer_dirty(struct extent_buffer *eb)
WARN_ON(test_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags));
if (!was_dirty) {
bool subpage = eb->fs_info->nodesize < PAGE_SIZE;
bool subpage = btrfs_meta_is_subpage(eb->fs_info);
/*
* For subpage case, we can have other extent buffers in the
@ -3472,7 +3472,7 @@ void clear_extent_buffer_uptodate(struct extent_buffer *eb)
* This is special handling for metadata subpage, as regular
* btrfs_is_subpage() can not handle cloned/dummy metadata.
*/
if (fs_info->nodesize >= PAGE_SIZE)
if (!btrfs_meta_is_subpage(fs_info))
folio_clear_uptodate(folio);
else
btrfs_subpage_clear_uptodate(fs_info, folio,
@ -3493,7 +3493,7 @@ void set_extent_buffer_uptodate(struct extent_buffer *eb)
* This is special handling for metadata subpage, as regular
* btrfs_is_subpage() can not handle cloned/dummy metadata.
*/
if (fs_info->nodesize >= PAGE_SIZE)
if (!btrfs_meta_is_subpage(fs_info))
folio_mark_uptodate(folio);
else
btrfs_subpage_set_uptodate(fs_info, folio,
@ -3583,7 +3583,7 @@ int read_extent_buffer_pages_nowait(struct extent_buffer *eb, int mirror_num,
bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
bbio->file_offset = eb->start;
memcpy(&bbio->parent_check, check, sizeof(*check));
if (eb->fs_info->nodesize < PAGE_SIZE) {
if (btrfs_meta_is_subpage(eb->fs_info)) {
ret = bio_add_folio(&bbio->bio, eb->folios[0], eb->len,
eb->start - folio_pos(eb->folios[0]));
ASSERT(ret);
@ -3784,7 +3784,7 @@ static void assert_eb_folio_uptodate(const struct extent_buffer *eb, int i)
if (test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
return;
if (fs_info->nodesize < PAGE_SIZE) {
if (btrfs_meta_is_subpage(fs_info)) {
folio = eb->folios[0];
ASSERT(i == 0);
if (WARN_ON(!btrfs_subpage_test_uptodate(fs_info, folio,
@ -4270,7 +4270,7 @@ int try_release_extent_buffer(struct folio *folio)
{
struct extent_buffer *eb;
if (folio_to_fs_info(folio)->nodesize < PAGE_SIZE)
if (btrfs_meta_is_subpage(folio_to_fs_info(folio)))
return try_release_subpage_extent_buffer(folio);
/*

4
fs/btrfs/subpage.c
View File

@ -169,7 +169,7 @@ void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *
{
struct btrfs_subpage *subpage;
if (!btrfs_is_subpage(fs_info, folio->mapping))
if (!btrfs_meta_is_subpage(fs_info))
return;
ASSERT(folio_test_private(folio) && folio->mapping);
@ -183,7 +183,7 @@ void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *
{
struct btrfs_subpage *subpage;
if (!btrfs_is_subpage(fs_info, folio->mapping))
if (!btrfs_meta_is_subpage(fs_info))
return;
ASSERT(folio_test_private(folio) && folio->mapping);

19
fs/btrfs/subpage.h
View File

@ -6,10 +6,10 @@
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/sizes.h>
#include "fs.h"
struct address_space;
struct folio;
struct btrfs_fs_info;
/*
* Extra info for subpapge bitmap.
@ -70,8 +70,25 @@ enum btrfs_subpage_type {
};
#if PAGE_SIZE > SZ_4K
/*
* Subpage support for metadata is more complex, as we can have dummy extent
* buffers, where folios have no mapping to determine the owning inode.
*
* Thankfully we only need to check if node size is smaller than page size.
* Even with larger folio support, we will only allocate a folio as large as
* node size.
* Thus if nodesize < PAGE_SIZE, we know metadata needs need to subpage routine.
*/
static inline bool btrfs_meta_is_subpage(const struct btrfs_fs_info *fs_info)
{
return fs_info->nodesize < PAGE_SIZE;
}
bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
#else
static inline bool btrfs_meta_is_subpage(const struct btrfs_fs_info *fs_info)
{
return false;
}
static inline bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info,
struct address_space *mapping)
{