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Mon, 7 Oct 2024 21:59:03 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id WA67OKdZBGfsfAAAD6G6ig (envelope-from ) for ; Mon, 07 Oct 2024 21:59:03 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH 1/2] btrfs: unify to use writer locks for subpage locking Date: Tue, 8 Oct 2024 08:28:44 +1030 Message-ID: <920be98203b75b89cad9ee617b1568e9dd45b305.1728338061.git.wqu@suse.com> X-Mailer: git-send-email 2.46.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Queue-Id: E270A1FF2E X-Spam-Level: X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; RCPT_COUNT_ONE(0.00)[1]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.com:+]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_NONE(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; PREVIOUSLY_DELIVERED(0.00)[linux-btrfs@vger.kernel.org]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.com:email,suse.com:dkim,suse.com:mid] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -3.01 X-Spam-Flag: NO 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 --- fs/btrfs/compression.c | 3 +- fs/btrfs/extent_io.c | 10 ++---- fs/btrfs/subpage.c | 82 ++---------------------------------------- fs/btrfs/subpage.h | 19 +++------- 4 files changed, 10 insertions(+), 104 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 0448cee2b983..04b190bc047f 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -436,7 +436,7 @@ 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); } /* @@ -493,7 +493,7 @@ 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); } /* @@ -2508,12 +2508,6 @@ 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 3c1e34ddda74..ed7f66963c0b 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -140,12 +140,9 @@ 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) { + atomic_set(&ret->writers, 0); + if (type == BTRFS_SUBPAGE_METADATA) atomic_set(&ret->eb_refs, 0); - } else { - atomic_set(&ret->readers, 0); - atomic_set(&ret->writers, 0); - } return ret; } @@ -240,81 +237,6 @@ static void assert_bitmap_range_all_zero(const struct btrfs_fs_info *fs_info, } } -static void assert_bitmap_range_all_set(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; - int all_set; - - lockdep_assert_held(&subpage->lock); - if (!IS_ENABLED(CONFIG_BTRFS_ASSERT)) - return; - - all_set = bitmap_test_range_all_set(subpage->bitmaps, start_bit, nbits); - if (unlikely(!all_set)) { - btrfs_subpage_dump_bitmap(fs_info, folio, start, len, true); - ASSERT(all_set); - } -} - -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_range_all_zero(fs_info, folio, start, len); - 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_range_all_set(fs_info, folio, start, len); - 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 cbee866152de..b6337543f7dd 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 @@ -62,7 +54,11 @@ struct btrfs_subpage { */ atomic_t eb_refs; - /* Structures only used by data */ + /* + * Structures only used by data, + * + * How many sectors inside the page is locked. + */ atomic_t writers; }; unsigned long bitmaps[]; @@ -95,11 +91,6 @@ 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,