From ef4e88e6a55babd825aed2940a72a0562f49ca7e Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 28 Jun 2023 17:31:24 +0200 Subject: [PATCH] btrfs: split page locking out of __process_pages_contig There is a lot of complexity in __process_pages_contig to deal with the PAGE_LOCK case that can return an error unlike all the other actions. Open code the page iteration for page locking in lock_delalloc_pages and remove all the now unused code from __process_pages_contig. Reviewed-by: Josef Bacik Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 151 ++++++++++++++++++++------------------------------- fs/btrfs/extent_io.h | 1 - 2 files changed, 59 insertions(+), 93 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 662d991..7925c8b 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -197,18 +197,9 @@ void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end) } } -/* - * Process one page for __process_pages_contig(). - * - * Return >0 if we hit @page == @locked_page. - * Return 0 if we updated the page status. - * Return -EGAIN if the we need to try again. - * (For PAGE_LOCK case but got dirty page or page not belong to mapping) - */ -static int process_one_page(struct btrfs_fs_info *fs_info, - struct address_space *mapping, - struct page *page, struct page *locked_page, - unsigned long page_ops, u64 start, u64 end) +static void process_one_page(struct btrfs_fs_info *fs_info, + struct page *page, struct page *locked_page, + unsigned long page_ops, u64 start, u64 end) { u32 len; @@ -224,94 +215,36 @@ static int process_one_page(struct btrfs_fs_info *fs_info, if (page_ops & PAGE_END_WRITEBACK) btrfs_page_clamp_clear_writeback(fs_info, page, start, len); - if (page == locked_page) - return 1; - - if (page_ops & PAGE_LOCK) { - int ret; - - ret = btrfs_page_start_writer_lock(fs_info, page, start, len); - if (ret) - return ret; - if (!PageDirty(page) || page->mapping != mapping) { - btrfs_page_end_writer_lock(fs_info, page, start, len); - return -EAGAIN; - } - } - if (page_ops & PAGE_UNLOCK) + if (page != locked_page && (page_ops & PAGE_UNLOCK)) btrfs_page_end_writer_lock(fs_info, page, start, len); - return 0; } -static int __process_pages_contig(struct address_space *mapping, - struct page *locked_page, - u64 start, u64 end, unsigned long page_ops, - u64 *processed_end) +static void __process_pages_contig(struct address_space *mapping, + struct page *locked_page, u64 start, u64 end, + unsigned long page_ops) { struct btrfs_fs_info *fs_info = btrfs_sb(mapping->host->i_sb); pgoff_t start_index = start >> PAGE_SHIFT; pgoff_t end_index = end >> PAGE_SHIFT; pgoff_t index = start_index; - unsigned long pages_processed = 0; struct folio_batch fbatch; - int err = 0; int i; - if (page_ops & PAGE_LOCK) { - ASSERT(page_ops == PAGE_LOCK); - ASSERT(processed_end && *processed_end == start); - } - folio_batch_init(&fbatch); while (index <= end_index) { int found_folios; found_folios = filemap_get_folios_contig(mapping, &index, end_index, &fbatch); - - if (found_folios == 0) { - /* - * Only if we're going to lock these pages, we can find - * nothing at @index. - */ - ASSERT(page_ops & PAGE_LOCK); - err = -EAGAIN; - goto out; - } - for (i = 0; i < found_folios; i++) { - int process_ret; struct folio *folio = fbatch.folios[i]; - process_ret = process_one_page(fs_info, mapping, - &folio->page, locked_page, page_ops, - start, end); - if (process_ret < 0) { - err = -EAGAIN; - folio_batch_release(&fbatch); - goto out; - } - pages_processed += folio_nr_pages(folio); + + process_one_page(fs_info, &folio->page, locked_page, + page_ops, start, end); } folio_batch_release(&fbatch); cond_resched(); } -out: - if (err && processed_end) { - /* - * Update @processed_end. I know this is awful since it has - * two different return value patterns (inclusive vs exclusive). - * - * But the exclusive pattern is necessary if @start is 0, or we - * underflow and check against processed_end won't work as - * expected. - */ - if (pages_processed) - *processed_end = min(end, - ((u64)(start_index + pages_processed) << PAGE_SHIFT) - 1); - else - *processed_end = start; - } - return err; } static noinline void __unlock_for_delalloc(struct inode *inode, @@ -326,29 +259,63 @@ static noinline void __unlock_for_delalloc(struct inode *inode, return; __process_pages_contig(inode->i_mapping, locked_page, start, end, - PAGE_UNLOCK, NULL); + PAGE_UNLOCK); } static noinline int lock_delalloc_pages(struct inode *inode, struct page *locked_page, - u64 delalloc_start, - u64 delalloc_end) + u64 start, + u64 end) { - unsigned long index = delalloc_start >> PAGE_SHIFT; - unsigned long end_index = delalloc_end >> PAGE_SHIFT; - u64 processed_end = delalloc_start; - int ret; + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct address_space *mapping = inode->i_mapping; + pgoff_t start_index = start >> PAGE_SHIFT; + pgoff_t end_index = end >> PAGE_SHIFT; + pgoff_t index = start_index; + u64 processed_end = start; + struct folio_batch fbatch; - ASSERT(locked_page); if (index == locked_page->index && index == end_index) return 0; - ret = __process_pages_contig(inode->i_mapping, locked_page, delalloc_start, - delalloc_end, PAGE_LOCK, &processed_end); - if (ret == -EAGAIN && processed_end > delalloc_start) - __unlock_for_delalloc(inode, locked_page, delalloc_start, - processed_end); - return ret; + folio_batch_init(&fbatch); + while (index <= end_index) { + unsigned int found_folios, i; + + found_folios = filemap_get_folios_contig(mapping, &index, + end_index, &fbatch); + if (found_folios == 0) + goto out; + + for (i = 0; i < found_folios; i++) { + struct page *page = &fbatch.folios[i]->page; + u32 len = end + 1 - start; + + if (page == locked_page) + continue; + + if (btrfs_page_start_writer_lock(fs_info, page, start, + len)) + goto out; + + if (!PageDirty(page) || page->mapping != mapping) { + btrfs_page_end_writer_lock(fs_info, page, start, + len); + goto out; + } + + processed_end = page_offset(page) + PAGE_SIZE - 1; + } + folio_batch_release(&fbatch); + cond_resched(); + } + + return 0; +out: + folio_batch_release(&fbatch); + if (processed_end > start) + __unlock_for_delalloc(inode, locked_page, start, processed_end); + return -EAGAIN; } /* @@ -467,7 +434,7 @@ void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end, clear_extent_bit(&inode->io_tree, start, end, clear_bits, NULL); __process_pages_contig(inode->vfs_inode.i_mapping, locked_page, - start, end, page_ops, NULL); + start, end, page_ops); } static bool btrfs_verify_page(struct page *page, u64 start) diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index c5fae3a..2857541 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -40,7 +40,6 @@ enum { ENUM_BIT(PAGE_START_WRITEBACK), ENUM_BIT(PAGE_END_WRITEBACK), ENUM_BIT(PAGE_SET_ORDERED), - ENUM_BIT(PAGE_LOCK), }; /* -- 2.7.4