* [PATCH v2 1/2] btrfs: unify to use writer locks for subpage locking
2024-10-09 5:51 [PATCH v2 0/2] btrfs: unify the read and writer locks for btrfs_subpage Qu Wenruo
@ 2024-10-09 5:51 ` Qu Wenruo
2024-10-09 5:51 ` [PATCH v2 2/2] btrfs: rename btrfs_folio_(set|start|end)_writer_lock() Qu Wenruo
2024-10-16 15:28 ` [PATCH v2 0/2] btrfs: unify the read and writer locks for btrfs_subpage David Sterba
2 siblings, 0 replies; 4+ messages in thread
From: Qu Wenruo @ 2024-10-09 5:51 UTC (permalink / raw)
To: linux-btrfs
Since commit d7172f52e993 ("btrfs: use per-buffer locking for
extent_buffer reading"), metadata read no longer relies on the subpage
reader locking.
This means we do not need to maintain a different metadata/data split
for locking, so we can convert the existing reader lock users by:
- add_ra_bio_pages()
Convert to btrfs_folio_set_writer_lock()
- end_folio_read()
Convert to btrfs_folio_end_writer_lock()
- begin_folio_read()
Convert to btrfs_folio_set_writer_lock()
- folio_range_has_eb()
Remove the subpage->readers checks, since it is always 0.
- Remove btrfs_subpage_start_reader() and btrfs_subpage_end_reader()
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/compression.c | 3 +-
fs/btrfs/extent_io.c | 10 ++-----
fs/btrfs/subpage.c | 62 ++----------------------------------------
fs/btrfs/subpage.h | 13 ---------
4 files changed, 5 insertions(+), 83 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 6e9c4a5e0d51..74799270eb78 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -545,8 +545,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
* subpage::readers and to unlock the page.
*/
if (fs_info->sectorsize < PAGE_SIZE)
- btrfs_subpage_start_reader(fs_info, folio, cur,
- add_size);
+ btrfs_folio_set_writer_lock(fs_info, folio, cur, add_size);
folio_put(folio);
cur += add_size;
}
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index bfa745258e9b..06d2b882bf8c 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -438,7 +438,7 @@ static void end_folio_read(struct folio *folio, bool uptodate, u64 start, u32 le
if (!btrfs_is_subpage(fs_info, folio->mapping))
folio_unlock(folio);
else
- btrfs_subpage_end_reader(fs_info, folio, start, len);
+ btrfs_folio_end_writer_lock(fs_info, folio, start, len);
}
/*
@@ -495,7 +495,7 @@ static void begin_folio_read(struct btrfs_fs_info *fs_info, struct folio *folio)
return;
ASSERT(folio_test_private(folio));
- btrfs_subpage_start_reader(fs_info, folio, folio_pos(folio), PAGE_SIZE);
+ btrfs_folio_set_writer_lock(fs_info, folio, folio_pos(folio), PAGE_SIZE);
}
/*
@@ -2517,12 +2517,6 @@ static bool folio_range_has_eb(struct btrfs_fs_info *fs_info, struct folio *foli
subpage = folio_get_private(folio);
if (atomic_read(&subpage->eb_refs))
return true;
- /*
- * Even there is no eb refs here, we may still have
- * end_folio_read() call relying on page::private.
- */
- if (atomic_read(&subpage->readers))
- return true;
}
return false;
}
diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c
index 26d4d05dd165..6c3d54a45956 100644
--- a/fs/btrfs/subpage.c
+++ b/fs/btrfs/subpage.c
@@ -140,12 +140,10 @@ struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
return ERR_PTR(-ENOMEM);
spin_lock_init(&ret->lock);
- if (type == BTRFS_SUBPAGE_METADATA) {
+ if (type == BTRFS_SUBPAGE_METADATA)
atomic_set(&ret->eb_refs, 0);
- } else {
- atomic_set(&ret->readers, 0);
+ else
atomic_set(&ret->writers, 0);
- }
return ret;
}
@@ -221,62 +219,6 @@ static void btrfs_subpage_assert(const struct btrfs_fs_info *fs_info,
__start_bit; \
})
-void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len)
-{
- struct btrfs_subpage *subpage = folio_get_private(folio);
- const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len);
- const int nbits = len >> fs_info->sectorsize_bits;
- unsigned long flags;
-
-
- btrfs_subpage_assert(fs_info, folio, start, len);
-
- spin_lock_irqsave(&subpage->lock, flags);
- /*
- * Even though it's just for reading the page, no one should have
- * locked the subpage range.
- */
- ASSERT(bitmap_test_range_all_zero(subpage->bitmaps, start_bit, nbits));
- bitmap_set(subpage->bitmaps, start_bit, nbits);
- atomic_add(nbits, &subpage->readers);
- spin_unlock_irqrestore(&subpage->lock, flags);
-}
-
-void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len)
-{
- struct btrfs_subpage *subpage = folio_get_private(folio);
- const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len);
- const int nbits = len >> fs_info->sectorsize_bits;
- unsigned long flags;
- bool is_data;
- bool last;
-
- btrfs_subpage_assert(fs_info, folio, start, len);
- is_data = is_data_inode(BTRFS_I(folio->mapping->host));
-
- spin_lock_irqsave(&subpage->lock, flags);
-
- /* The range should have already been locked. */
- ASSERT(bitmap_test_range_all_set(subpage->bitmaps, start_bit, nbits));
- ASSERT(atomic_read(&subpage->readers) >= nbits);
-
- bitmap_clear(subpage->bitmaps, start_bit, nbits);
- last = atomic_sub_and_test(nbits, &subpage->readers);
-
- /*
- * For data we need to unlock the page if the last read has finished.
- *
- * And please don't replace @last with atomic_sub_and_test() call
- * inside if () condition.
- * As we want the atomic_sub_and_test() to be always executed.
- */
- if (is_data && last)
- folio_unlock(folio);
- spin_unlock_irqrestore(&subpage->lock, flags);
-}
-
static void btrfs_subpage_clamp_range(struct folio *folio, u64 *start, u32 *len)
{
u64 orig_start = *start;
diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index e4076c5b06bc..c150aba9318e 100644
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -45,14 +45,6 @@ enum {
struct btrfs_subpage {
/* Common members for both data and metadata pages */
spinlock_t lock;
- /*
- * Both data and metadata needs to track how many readers are for the
- * page.
- * Data relies on @readers to unlock the page when last reader finished.
- * While metadata doesn't need page unlock, it needs to prevent
- * page::private get cleared before the last end_page_read().
- */
- atomic_t readers;
union {
/*
* Structures only used by metadata
@@ -95,11 +87,6 @@ void btrfs_free_subpage(struct btrfs_subpage *subpage);
void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
-void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len);
-void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len);
-
void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info,
--
2.46.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v2 2/2] btrfs: rename btrfs_folio_(set|start|end)_writer_lock()
2024-10-09 5:51 [PATCH v2 0/2] btrfs: unify the read and writer locks for btrfs_subpage Qu Wenruo
2024-10-09 5:51 ` [PATCH v2 1/2] btrfs: unify to use writer locks for subpage locking Qu Wenruo
@ 2024-10-09 5:51 ` Qu Wenruo
2024-10-16 15:28 ` [PATCH v2 0/2] btrfs: unify the read and writer locks for btrfs_subpage David Sterba
2 siblings, 0 replies; 4+ messages in thread
From: Qu Wenruo @ 2024-10-09 5:51 UTC (permalink / raw)
To: linux-btrfs
Since there is no user of reader locks, rename the writer locks into a
more generic name, by removing the "_writer" part from the name.
And also rename btrfs_subpage::writer into btrfs_subpage::locked.
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/compression.c | 2 +-
fs/btrfs/extent_io.c | 14 ++++++-------
fs/btrfs/subpage.c | 46 +++++++++++++++++++++---------------------
fs/btrfs/subpage.h | 20 ++++++++++--------
4 files changed, 43 insertions(+), 39 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 74799270eb78..dfa872cf09d5 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -545,7 +545,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
* subpage::readers and to unlock the page.
*/
if (fs_info->sectorsize < PAGE_SIZE)
- btrfs_folio_set_writer_lock(fs_info, folio, cur, add_size);
+ btrfs_folio_set_lock(fs_info, folio, cur, add_size);
folio_put(folio);
cur += add_size;
}
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 06d2b882bf8c..f94def65e83b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -190,7 +190,7 @@ static void process_one_folio(struct btrfs_fs_info *fs_info,
btrfs_folio_clamp_clear_writeback(fs_info, folio, start, len);
if (folio != locked_folio && (page_ops & PAGE_UNLOCK))
- btrfs_folio_end_writer_lock(fs_info, folio, start, len);
+ btrfs_folio_end_lock(fs_info, folio, start, len);
}
static void __process_folios_contig(struct address_space *mapping,
@@ -276,7 +276,7 @@ static noinline int lock_delalloc_folios(struct inode *inode,
range_start = max_t(u64, folio_pos(folio), start);
range_len = min_t(u64, folio_pos(folio) + folio_size(folio),
end + 1) - range_start;
- btrfs_folio_set_writer_lock(fs_info, folio, range_start, range_len);
+ btrfs_folio_set_lock(fs_info, folio, range_start, range_len);
processed_end = range_start + range_len - 1;
}
@@ -438,7 +438,7 @@ static void end_folio_read(struct folio *folio, bool uptodate, u64 start, u32 le
if (!btrfs_is_subpage(fs_info, folio->mapping))
folio_unlock(folio);
else
- btrfs_folio_end_writer_lock(fs_info, folio, start, len);
+ btrfs_folio_end_lock(fs_info, folio, start, len);
}
/*
@@ -495,7 +495,7 @@ static void begin_folio_read(struct btrfs_fs_info *fs_info, struct folio *folio)
return;
ASSERT(folio_test_private(folio));
- btrfs_folio_set_writer_lock(fs_info, folio, folio_pos(folio), PAGE_SIZE);
+ btrfs_folio_set_lock(fs_info, folio, folio_pos(folio), PAGE_SIZE);
}
/*
@@ -1184,7 +1184,7 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
for_each_set_bit(bit, &bio_ctrl->submit_bitmap, fs_info->sectors_per_page) {
u64 start = page_start + (bit << fs_info->sectorsize_bits);
- btrfs_folio_set_writer_lock(fs_info, folio, start, fs_info->sectorsize);
+ btrfs_folio_set_lock(fs_info, folio, start, fs_info->sectorsize);
}
/* Lock all (subpage) delalloc ranges inside the folio first. */
@@ -1520,7 +1520,7 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl
* Only unlock ranges that are submitted. As there can be some async
* submitted ranges inside the folio.
*/
- btrfs_folio_end_writer_lock_bitmap(fs_info, folio, bio_ctrl->submit_bitmap);
+ btrfs_folio_end_lock_bitmap(fs_info, folio, bio_ctrl->submit_bitmap);
ASSERT(ret <= 0);
return ret;
}
@@ -2298,7 +2298,7 @@ void extent_write_locked_range(struct inode *inode, const struct folio *locked_f
cur, cur_len, !ret);
mapping_set_error(mapping, ret);
}
- btrfs_folio_end_writer_lock(fs_info, folio, cur, cur_len);
+ btrfs_folio_end_lock(fs_info, folio, cur, cur_len);
if (ret < 0)
found_error = true;
next_page:
diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c
index 6c3d54a45956..d4cab3c55742 100644
--- a/fs/btrfs/subpage.c
+++ b/fs/btrfs/subpage.c
@@ -143,7 +143,7 @@ struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
if (type == BTRFS_SUBPAGE_METADATA)
atomic_set(&ret->eb_refs, 0);
else
- atomic_set(&ret->writers, 0);
+ atomic_set(&ret->nr_locked, 0);
return ret;
}
@@ -237,8 +237,8 @@ static void btrfs_subpage_clamp_range(struct folio *folio, u64 *start, u32 *len)
orig_start + orig_len) - *start;
}
-static bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len)
+static bool btrfs_subpage_end_and_test_lock(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, u64 start, u32 len)
{
struct btrfs_subpage *subpage = folio_get_private(folio);
const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len);
@@ -256,9 +256,9 @@ static bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_inf
* extent_clear_unlock_delalloc() for compression path.
*
* This @locked_page is locked by plain lock_page(), thus its
- * subpage::writers is 0. Handle them in a special way.
+ * subpage::locked is 0. Handle them in a special way.
*/
- if (atomic_read(&subpage->writers) == 0) {
+ if (atomic_read(&subpage->nr_locked) == 0) {
spin_unlock_irqrestore(&subpage->lock, flags);
return true;
}
@@ -267,8 +267,8 @@ static bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_inf
clear_bit(bit, subpage->bitmaps);
cleared++;
}
- ASSERT(atomic_read(&subpage->writers) >= cleared);
- last = atomic_sub_and_test(cleared, &subpage->writers);
+ ASSERT(atomic_read(&subpage->nr_locked) >= cleared);
+ last = atomic_sub_and_test(cleared, &subpage->nr_locked);
spin_unlock_irqrestore(&subpage->lock, flags);
return last;
}
@@ -289,8 +289,8 @@ static bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_inf
* bitmap, reduce the writer lock number, and unlock the page if that's
* the last locked range.
*/
-void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len)
+void btrfs_folio_end_lock(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, u64 start, u32 len)
{
struct btrfs_subpage *subpage = folio_get_private(folio);
@@ -303,24 +303,24 @@ void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
/*
* For subpage case, there are two types of locked page. With or
- * without writers number.
+ * without locked number.
*
- * Since we own the page lock, no one else could touch subpage::writers
+ * Since we own the page lock, no one else could touch subpage::locked
* and we are safe to do several atomic operations without spinlock.
*/
- if (atomic_read(&subpage->writers) == 0) {
- /* No writers, locked by plain lock_page(). */
+ if (atomic_read(&subpage->nr_locked) == 0) {
+ /* No subpage lock, locked by plain lock_page(). */
folio_unlock(folio);
return;
}
btrfs_subpage_clamp_range(folio, &start, &len);
- if (btrfs_subpage_end_and_test_writer(fs_info, folio, start, len))
+ if (btrfs_subpage_end_and_test_lock(fs_info, folio, start, len))
folio_unlock(folio);
}
-void btrfs_folio_end_writer_lock_bitmap(const struct btrfs_fs_info *fs_info,
- struct folio *folio, unsigned long bitmap)
+void btrfs_folio_end_lock_bitmap(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, unsigned long bitmap)
{
struct btrfs_subpage *subpage = folio_get_private(folio);
const int start_bit = fs_info->sectors_per_page * btrfs_bitmap_nr_locked;
@@ -334,8 +334,8 @@ void btrfs_folio_end_writer_lock_bitmap(const struct btrfs_fs_info *fs_info,
return;
}
- if (atomic_read(&subpage->writers) == 0) {
- /* No writers, locked by plain lock_page(). */
+ if (atomic_read(&subpage->nr_locked) == 0) {
+ /* No subpage lock, locked by plain lock_page(). */
folio_unlock(folio);
return;
}
@@ -345,8 +345,8 @@ void btrfs_folio_end_writer_lock_bitmap(const struct btrfs_fs_info *fs_info,
if (test_and_clear_bit(bit + start_bit, subpage->bitmaps))
cleared++;
}
- ASSERT(atomic_read(&subpage->writers) >= cleared);
- last = atomic_sub_and_test(cleared, &subpage->writers);
+ ASSERT(atomic_read(&subpage->nr_locked) >= cleared);
+ last = atomic_sub_and_test(cleared, &subpage->nr_locked);
spin_unlock_irqrestore(&subpage->lock, flags);
if (last)
folio_unlock(folio);
@@ -671,8 +671,8 @@ void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info,
* This populates the involved subpage ranges so that subpage helpers can
* properly unlock them.
*/
-void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len)
+void btrfs_folio_set_lock(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, u64 start, u32 len)
{
struct btrfs_subpage *subpage;
unsigned long flags;
@@ -691,7 +691,7 @@ void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info,
/* Target range should not yet be locked. */
ASSERT(bitmap_test_range_all_zero(subpage->bitmaps, start_bit, nbits));
bitmap_set(subpage->bitmaps, start_bit, nbits);
- ret = atomic_add_return(nbits, &subpage->writers);
+ ret = atomic_add_return(nbits, &subpage->nr_locked);
ASSERT(ret <= fs_info->sectors_per_page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index c150aba9318e..428fa9389fd4 100644
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -54,8 +54,12 @@ struct btrfs_subpage {
*/
atomic_t eb_refs;
- /* Structures only used by data */
- atomic_t writers;
+ /*
+ * Structures only used by data,
+ *
+ * How many sectors inside the page is locked.
+ */
+ atomic_t nr_locked;
};
unsigned long bitmaps[];
};
@@ -87,12 +91,12 @@ void btrfs_free_subpage(struct btrfs_subpage *subpage);
void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
-void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len);
-void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info,
- struct folio *folio, u64 start, u32 len);
-void btrfs_folio_end_writer_lock_bitmap(const struct btrfs_fs_info *fs_info,
- struct folio *folio, unsigned long bitmap);
+void btrfs_folio_end_lock(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, u64 start, u32 len);
+void btrfs_folio_set_lock(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, u64 start, u32 len);
+void btrfs_folio_end_lock_bitmap(const struct btrfs_fs_info *fs_info,
+ struct folio *folio, unsigned long bitmap);
/*
* Template for subpage related operations.
*
--
2.46.2
^ permalink raw reply related [flat|nested] 4+ messages in thread