From e94e54e89b4f9cbbdc2dbbf0c44adae0f4722ab6 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 28 Jun 2023 17:31:36 +0200 Subject: [PATCH] btrfs: streamline compress_file_range Reorder compress_file_range so that the main compression flow happens straight line and not in branches. To do this ensure that pages is always zeroed before a page allocation happens, which allows the cleanup_and_bail_uncompressed label to clean up the page allocations as needed. Reviewed-by: Josef Bacik Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 167 +++++++++++++++++++++++------------------------ 1 file changed, 83 insertions(+), 84 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b119d828cc4e..e994582358e0 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -839,10 +839,11 @@ static void compress_file_range(struct btrfs_work *work) u64 actual_end; u64 i_size; int ret = 0; - struct page **pages = NULL; + struct page **pages; unsigned long nr_pages; unsigned long total_compressed = 0; unsigned long total_in = 0; + unsigned int poff; int i; int will_compress; int compress_type = fs_info->compress_type; @@ -865,6 +866,7 @@ static void compress_file_range(struct btrfs_work *work) actual_end = min_t(u64, i_size, end + 1); again: will_compress = 0; + pages = NULL; nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1; nr_pages = min_t(unsigned long, nr_pages, BTRFS_MAX_COMPRESSED_PAGES); @@ -908,66 +910,64 @@ again: ret = 0; /* - * we do compression for mount -o compress and when the - * inode has not been flagged as nocompress. This flag can - * change at any time if we discover bad compression ratios. + * We do compression for mount -o compress and when the inode has not + * been flagged as NOCOMPRESS. This flag can change at any time if we + * discover bad compression ratios. */ - if (inode_need_compress(inode, start, end)) { - WARN_ON(pages); - pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); - if (!pages) { - /* just bail out to the uncompressed code */ - nr_pages = 0; - goto cont; - } - - if (inode->defrag_compress) - compress_type = inode->defrag_compress; - else if (inode->prop_compress) - compress_type = inode->prop_compress; + if (!inode_need_compress(inode, start, end)) + goto cont; + pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); + if (!pages) { /* - * we need to call clear_page_dirty_for_io on each - * page in the range. Otherwise applications with the file - * mmap'd can wander in and change the page contents while - * we are compressing them. - * - * If the compression fails for any reason, we set the pages - * dirty again later on. - * - * Note that the remaining part is redirtied, the start pointer - * has moved, the end is the original one. + * Memory allocation failure is not a fatal error, we can fall + * back to uncompressed code. */ - if (!redirty) { - extent_range_clear_dirty_for_io(&inode->vfs_inode, start, end); - redirty = 1; - } - - /* Compression level is applied here and only here */ - ret = btrfs_compress_pages( - compress_type | (fs_info->compress_level << 4), - mapping, start, - pages, - &nr_pages, - &total_in, - &total_compressed); - - if (!ret) { - unsigned long offset = offset_in_page(total_compressed); - struct page *page = pages[nr_pages - 1]; - - /* zero the tail end of the last page, we might be - * sending it down to disk - */ - if (offset) - memzero_page(page, offset, PAGE_SIZE - offset); - will_compress = 1; - } + nr_pages = 0; + goto cont; } + + if (inode->defrag_compress) + compress_type = inode->defrag_compress; + else if (inode->prop_compress) + compress_type = inode->prop_compress; + + /* + * We need to call clear_page_dirty_for_io on each page in the range. + * Otherwise applications with the file mmap'd can wander in and change + * the page contents while we are compressing them. + * + * If the compression fails for any reason, we set the pages dirty again + * later on. + * + * Note that the remaining part is redirtied, the start pointer has + * moved, the end is the original one. + */ + if (!redirty) { + extent_range_clear_dirty_for_io(&inode->vfs_inode, start, end); + redirty = 1; + } + + /* Compression level is applied here. */ + ret = btrfs_compress_pages(compress_type | (fs_info->compress_level << 4), + mapping, start, pages, &nr_pages, &total_in, + &total_compressed); + if (ret) + goto cont; + + /* + * Zero the tail end of the last page, as we might be sending it down + * to disk. + */ + poff = offset_in_page(total_compressed); + if (poff) + memzero_page(pages[nr_pages - 1], poff, PAGE_SIZE - poff); + will_compress = 1; + cont: /* * Check cow_file_range() for why we don't even try to create inline - * extent for subpage case. + * extent for the subpage case. */ if (start == 0 && fs_info->sectorsize == PAGE_SIZE) { /* lets try to make an inline extent */ @@ -1026,39 +1026,38 @@ cont: } } - if (will_compress) { - /* - * we aren't doing an inline extent round the compressed size - * up to a block size boundary so the allocator does sane - * things - */ - total_compressed = ALIGN(total_compressed, blocksize); + if (!will_compress) + goto cleanup_and_bail_uncompressed; - /* - * one last check to make sure the compression is really a - * win, compare the page count read with the blocks on disk, - * compression must free at least one sector size - */ - total_in = round_up(total_in, fs_info->sectorsize); - if (total_compressed + blocksize <= total_in) { - /* - * The async work queues will take care of doing actual - * allocation on disk for these compressed pages, and - * will submit them to the elevator. - */ - add_async_extent(async_chunk, start, total_in, - total_compressed, pages, nr_pages, - compress_type); + /* + * We aren't doing an inline extent. Round the compressed size up to a + * block size boundary so the allocator does sane things. + */ + total_compressed = ALIGN(total_compressed, blocksize); - if (start + total_in < end) { - start += total_in; - pages = NULL; - cond_resched(); - goto again; - } - return; - } + /* + * One last check to make sure the compression is really a win, compare + * the page count read with the blocks on disk, compression must free at + * least one sector. + */ + total_in = round_up(total_in, fs_info->sectorsize); + if (total_compressed + blocksize > total_in) + goto cleanup_and_bail_uncompressed; + + /* + * The async work queues will take care of doing actual allocation on + * disk for these compressed pages, and will submit the bios. + */ + add_async_extent(async_chunk, start, total_in, total_compressed, pages, + nr_pages, compress_type); + if (start + total_in < end) { + start += total_in; + cond_resched(); + goto again; } + return; + +cleanup_and_bail_uncompressed: if (pages) { /* * the compression code ran but failed to make things smaller, @@ -1079,7 +1078,7 @@ cont: inode->flags |= BTRFS_INODE_NOCOMPRESS; } } -cleanup_and_bail_uncompressed: + /* * No compression, but we still need to write the pages in the file * we've been given so far. redirty the locked page if it corresponds