From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sxb1plsmtpa01-03.prod.sxb1.secureserver.net (sxb1plsmtpa01-03.prod.sxb1.secureserver.net [188.121.53.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5ADAC288C8B for ; Tue, 23 Sep 2025 22:14:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=188.121.53.28 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758665653; cv=none; b=SbPgM0hZRKG7YACUHDxKk2kUUwb315fn0DER7igD2R9O3L7oWFO56GaI+vBMc9kVI8AH0KjeM6A/DP0ZQtrlhykBOa+Y3PoXzFWG9Hw81oM3hX6NEIKdq0gWtfJEOSs7VWUlRha+sGeMv7mvP+6CF0JCjqXYEZGGG543oLjnVaQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758665653; c=relaxed/simple; bh=WUP0gLZZhYvaPyUD0UMhst8lpJlJkhpbcn69k5v/iSo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Lu8OmMWDcIrbqXpFDdfpJuUSsnLgf+hOCqUdzz9/bfgNDj7Q2qKwwad3HF3Cg3OY45OThWLAfoni7dLEasvA46GITH9wBy5ae9BcHEodCRQPUNrYieGNtmIYHHxw8WKHZQdaCPh9F/D7ESuOjCVpHDJQ7hiwED/Hc2fFy9KYEgI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=squashfs.org.uk; spf=pass smtp.mailfrom=squashfs.org.uk; arc=none smtp.client-ip=188.121.53.28 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=squashfs.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=squashfs.org.uk Received: from phoenix.fritz.box ([82.69.79.175]) by :SMTPAUTH: with ESMTPA id 1B9IvdJrlRKdg1B9Yvhvt4; Tue, 23 Sep 2025 15:06:29 -0700 X-CMAE-Analysis: v=2.4 cv=cL65cleN c=1 sm=1 tr=0 ts=68d319e6 a=84ok6UeoqCVsigPHarzEiQ==:117 a=84ok6UeoqCVsigPHarzEiQ==:17 a=FXvPX3liAAAA:8 a=PmvtE5NTWYoDmZ2mIecA:9 a=UObqyxdv-6Yh2QiB9mM_:22 a=irvUdcZYBsSKPCvlqN3O:22 Feedback-ID: e4ba3dcc65f267fca773178bb1f8c56e:squashfs.org.uk:ssnet X-SECURESERVER-ACCT: phillip@squashfs.org.uk From: Phillip Lougher To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org Cc: Phillip Lougher Subject: [PATCH 2/2] Squashfs: add SEEK_DATA/SEEK_HOLE support Date: Tue, 23 Sep 2025 23:06:52 +0100 Message-Id: <20250923220652.568416-3-phillip@squashfs.org.uk> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250923220652.568416-1-phillip@squashfs.org.uk> References: <20250923220652.568416-1-phillip@squashfs.org.uk> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CMAE-Envelope: MS4xfFzgAGs/sxXFVE9lZdAnY+CuxBiOxHex/bXKVsLtYWDr7c7WHCSJKyDlLmE5fkACUJFckEwMpEQf5UnePwsUiyRaaFN3sXNJFKVWNcNw8sj/W71So3Mq 5xy6L+8P6uXLJpLBqmx2hiyxe75EZDhngl6CbpL4STnrrO6vjjqEyUvThlRlmE7wIFDEbh6+jfI5I3Ew5GZzpCxOpFdUNIoeFK+DaLGejcXDsBjt19hCDL6r rjYBlJoi5N8UY80ywA9L5bQRvmD72FiLVwh9RIdNGSyY25xEIypExPIzzy5OOmqs Add support for SEEK_DATA and SEEK_HOLE lseek() whence values. These allow much faster searches for holes and data in sparse files, which can significantly speed up file copying, e.g. before (GNU coreutils, Debian 13): cp --sparse=always big-file / took real 11m58s, user 0m5.764s, sys 11m48s after: real 0.047s, user 0.000s, sys 0.027s Where big-file has a 256 GB hole followed by 47 KB of data. Signed-off-by: Phillip Lougher --- fs/squashfs/file.c | 137 +++++++++++++++++++++++++++++++++++--- fs/squashfs/inode.c | 4 +- fs/squashfs/squashfs.h | 1 + fs/squashfs/squashfs_fs.h | 1 + 4 files changed, 130 insertions(+), 13 deletions(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index ce7d661d5ad8..1582e0637a7e 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -307,7 +307,8 @@ static int fill_meta_index(struct inode *inode, int index, all_done: *index_block = cur_index_block; *index_offset = cur_offset; - *data_block = cur_data_block; + if (data_block) + *data_block = cur_data_block; /* * Scale cache index (cache slot entry) to index @@ -324,17 +325,15 @@ static int fill_meta_index(struct inode *inode, int index, * Get the on-disk location and compressed size of the datablock * specified by index. Fill_meta_index() does most of the work. */ -static int read_blocklist(struct inode *inode, int index, u64 *block) +static int read_blocklist_ptrs(struct inode *inode, int index, u64 *start, + int *offset, u64 *block) { - u64 start; long long blks; - int offset; __le32 size; - int res = fill_meta_index(inode, index, &start, &offset, block); + int res = fill_meta_index(inode, index, start, offset, block); - TRACE("read_blocklist: res %d, index %d, start 0x%llx, offset" - " 0x%x, block 0x%llx\n", res, index, start, offset, - *block); + TRACE("read_blocklist: res %d, index %d, start 0x%llx, offset 0x%x, block 0x%llx\n", + res, index, *start, *offset, block ? *block : 0); if (res < 0) return res; @@ -346,22 +345,31 @@ static int read_blocklist(struct inode *inode, int index, u64 *block) * extra block indexes needed. */ if (res < index) { - blks = read_indexes(inode->i_sb, index - res, &start, &offset); + blks = read_indexes(inode->i_sb, index - res, start, offset); if (blks < 0) return (int) blks; - *block += blks; + if (block) + *block += blks; } /* * Read length of block specified by index. */ - res = squashfs_read_metadata(inode->i_sb, &size, &start, &offset, + res = squashfs_read_metadata(inode->i_sb, &size, start, offset, sizeof(size)); if (res < 0) return res; return squashfs_block_size(size); } +static inline int read_blocklist(struct inode *inode, int index, u64 *block) +{ + u64 start; + int offset; + + return read_blocklist_ptrs(inode, index, &start, &offset, block); +} + static bool squashfs_fill_page(struct folio *folio, struct squashfs_cache_entry *buffer, size_t offset, size_t avail) @@ -658,7 +666,114 @@ static void squashfs_readahead(struct readahead_control *ractl) kfree(pages); } +static loff_t seek_hole_data(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file->f_mapping->host; + struct super_block *sb = inode->i_sb; + struct squashfs_sb_info *msblk = sb->s_fs_info; + u64 start, index = offset >> msblk->block_log; + u64 file_end = (i_size_read(inode) + msblk->block_size - 1) >> msblk->block_log; + int s_offset, length; + __le32 *blist = NULL; + + /* reject offset if negative or beyond file end */ + if ((unsigned long long)offset >= i_size_read(inode)) + return -ENXIO; + + /* is offset within tailend and is tailend packed into a fragment? */ + if (index + 1 == file_end && + squashfs_i(inode)->fragment_block != SQUASHFS_INVALID_BLK) { + if (whence == SEEK_DATA) + return offset; + + /* there is an implicit hole at the end of any file */ + return i_size_read(inode); + } + + length = read_blocklist_ptrs(inode, index, &start, &s_offset, NULL); + if (length < 0) + return length; + + /* nothing more to do if offset matches desired whence value */ + if ((length == 0 && whence == SEEK_HOLE) || + (length && whence == SEEK_DATA)) + return offset; + + /* skip scanning forwards if we're at file end */ + if (++ index == file_end) + goto not_found; + + blist = kmalloc(SQUASHFS_SCAN_INDEXES << 2, GFP_KERNEL); + if (blist == NULL) { + ERROR("%s: Failed to allocate block_list\n", __func__); + return -ENOMEM; + } + + while (index < file_end) { + int i, indexes = min(file_end - index, SQUASHFS_SCAN_INDEXES); + + offset = squashfs_read_metadata(sb, blist, &start, &s_offset, indexes << 2); + if (offset < 0) + goto finished; + + for (i = 0; i < indexes; i++) { + length = squashfs_block_size(blist[i]); + if (length < 0) { + offset = length; + goto finished; + } + + /* does this block match desired whence value? */ + if ((length == 0 && whence == SEEK_HOLE) || + (length && whence == SEEK_DATA)) { + offset = (index + i) << msblk->block_log; + goto finished; + } + } + + index += indexes; + } + +not_found: + /* whence value determines what happens */ + if (whence == SEEK_DATA) + offset = -ENXIO; + else + /* there is an implicit hole at the end of any file */ + offset = i_size_read(inode); + +finished: + kfree(blist); + return offset; +} + +static loff_t squashfs_llseek(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file->f_mapping->host; + + switch (whence) { + default: + return generic_file_llseek(file, offset, whence); + case SEEK_DATA: + case SEEK_HOLE: + offset = seek_hole_data(file, offset, whence); + break; + } + + if (offset < 0) + return offset; + + return vfs_setpos(file, offset, inode->i_sb->s_maxbytes); +} + const struct address_space_operations squashfs_aops = { .read_folio = squashfs_read_folio, .readahead = squashfs_readahead }; + +const struct file_operations squashfs_file_operations = { + .llseek = squashfs_llseek, + .read_iter = generic_file_read_iter, + .mmap_prepare = generic_file_readonly_mmap_prepare, + .splice_read = filemap_splice_read +}; diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c index 77eec1772998..5920a33e44a1 100644 --- a/fs/squashfs/inode.c +++ b/fs/squashfs/inode.c @@ -164,7 +164,7 @@ int squashfs_read_inode(struct inode *inode, long long ino) } set_nlink(inode, 1); - inode->i_fop = &generic_ro_fops; + inode->i_fop = &squashfs_file_operations; inode->i_mode |= S_IFREG; inode->i_blocks = ((inode->i_size - 1) >> 9) + 1; squashfs_i(inode)->fragment_block = frag_blk; @@ -217,7 +217,7 @@ int squashfs_read_inode(struct inode *inode, long long ino) xattr_id = le32_to_cpu(sqsh_ino->xattr); set_nlink(inode, le32_to_cpu(sqsh_ino->nlink)); inode->i_op = &squashfs_inode_ops; - inode->i_fop = &generic_ro_fops; + inode->i_fop = &squashfs_file_operations; inode->i_mode |= S_IFREG; inode->i_blocks = (inode->i_size - le64_to_cpu(sqsh_ino->sparse) + 511) >> 9; diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h index 218868b20f16..4851bd964502 100644 --- a/fs/squashfs/squashfs.h +++ b/fs/squashfs/squashfs.h @@ -107,6 +107,7 @@ extern const struct address_space_operations squashfs_aops; /* inode.c */ extern const struct inode_operations squashfs_inode_ops; +extern const struct file_operations squashfs_file_operations; /* namei.c */ extern const struct inode_operations squashfs_dir_inode_ops; diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h index 95f8e8901768..a955d9369749 100644 --- a/fs/squashfs/squashfs_fs.h +++ b/fs/squashfs/squashfs_fs.h @@ -208,6 +208,7 @@ static inline int squashfs_block_size(__le32 raw) #define SQUASHFS_META_INDEXES (SQUASHFS_METADATA_SIZE / sizeof(unsigned int)) #define SQUASHFS_META_ENTRIES 127 #define SQUASHFS_META_SLOTS 8 +#define SQUASHFS_SCAN_INDEXES 1024 struct meta_entry { u64 data_block; -- 2.39.5