From patchwork Fri Oct 18 04:50:08 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Darrick Wong X-Patchwork-Id: 284418 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 62B762C0379 for ; Fri, 18 Oct 2013 15:50:14 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751016Ab3JREuN (ORCPT ); Fri, 18 Oct 2013 00:50:13 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:30613 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750984Ab3JREuN (ORCPT ); Fri, 18 Oct 2013 00:50:13 -0400 Received: from ucsinet21.oracle.com (ucsinet21.oracle.com [156.151.31.93]) by aserp1040.oracle.com (Sentrion-MTA-4.3.1/Sentrion-MTA-4.3.1) with ESMTP id r9I4oAhx006204 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 18 Oct 2013 04:50:11 GMT Received: from userz7021.oracle.com (userz7021.oracle.com [156.151.31.85]) by ucsinet21.oracle.com (8.14.4+Sun/8.14.4) with ESMTP id r9I4oAeo020470 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 18 Oct 2013 04:50:10 GMT Received: from abhmt107.oracle.com (abhmt107.oracle.com [141.146.116.59]) by userz7021.oracle.com (8.14.4+Sun/8.14.4) with ESMTP id r9I4o9BI020460; Fri, 18 Oct 2013 04:50:09 GMT Received: from localhost (/67.160.151.179) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 17 Oct 2013 21:50:09 -0700 Subject: [PATCH 11/25] libext2fs: only punch complete clusters To: tytso@mit.edu, darrick.wong@oracle.com From: "Darrick J. Wong" Cc: linux-ext4@vger.kernel.org Date: Thu, 17 Oct 2013 21:50:08 -0700 Message-ID: <20131018045008.7339.73690.stgit@birch.djwong.org> In-Reply-To: <20131018044854.7339.48457.stgit@birch.djwong.org> References: <20131018044854.7339.48457.stgit@birch.djwong.org> User-Agent: StGit/0.15 MIME-Version: 1.0 X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org When bigalloc is enabled, using ext2fs_block_alloc_stats2() to free any block in a cluster has the effect of freeing the entire cluster. This is problematic if a caller instructs us to punch, say, blocks 12-15 of a 16-block cluster, because blocks 0-11 now point to a "free" cluster. The naive way to solve this problem is to see if any of the other blocks in this logical cluster map to a physical cluster. If so, then we know that the cluster is still in use and it mustn't be freed. Otherwise, we are punching the last mapped block in this cluster, so we can free the cluster. The implementation given only does the rigorous checks for the partial clusters at the beginning and end of the punching range. v2: Refactor the block free code into a separate helper function that should be more efficient. Signed-off-by: Darrick J. Wong Reviewed-by: Zheng Liu --- lib/ext2fs/bmap.c | 29 ++++++++++++++++++ lib/ext2fs/ext2fs.h | 3 ++ lib/ext2fs/punch.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 109 insertions(+), 5 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/lib/ext2fs/bmap.c b/lib/ext2fs/bmap.c index 5074587..80f8f86 100644 --- a/lib/ext2fs/bmap.c +++ b/lib/ext2fs/bmap.c @@ -173,6 +173,35 @@ static errcode_t implied_cluster_alloc(ext2_filsys fs, ext2_ino_t ino, return 0; } +/* Try to map a logical block to an already-allocated physical cluster. */ +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, blk64_t lblk, + blk64_t *pblk) +{ + ext2_extent_handle_t handle; + errcode_t retval; + + /* Need bigalloc and extents to be enabled */ + *pblk = 0; + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, + EXT4_FEATURE_RO_COMPAT_BIGALLOC) || + !(inode->i_flags & EXT4_EXTENTS_FL)) + return 0; + + retval = ext2fs_extent_open2(fs, ino, inode, &handle); + if (retval) + goto out; + + retval = implied_cluster_alloc(fs, ino, inode, handle, lblk, pblk); + if (retval) + goto out2; + +out2: + ext2fs_extent_free(handle); +out: + return retval; +} + static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, ext2_extent_handle_t handle, diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h index 8f82dae..5247922 100644 --- a/lib/ext2fs/ext2fs.h +++ b/lib/ext2fs/ext2fs.h @@ -924,6 +924,9 @@ extern errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, char *block_buf, int bmap_flags, blk64_t block, int *ret_flags, blk64_t *phys_blk); +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, blk64_t lblk, + blk64_t *pblk); #if 0 /* bmove.c */ diff --git a/lib/ext2fs/punch.c b/lib/ext2fs/punch.c index 790a0ad8..1e4398e 100644 --- a/lib/ext2fs/punch.c +++ b/lib/ext2fs/punch.c @@ -177,6 +177,75 @@ static void dbg_print_extent(char *desc, struct ext2fs_extent *extent) #define dbg_printf(f, a...) do { } while (0) #endif +/* Free a range of blocks, respecting cluster boundaries */ +static errcode_t punch_extent_blocks(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, + blk64_t lfree_start, blk64_t free_start, + __u32 free_count, int *freed) +{ + blk64_t pblk; + int freed_now = 0; + __u32 cluster_freed; + errcode_t retval = 0; + + /* No bigalloc? Just free each block. */ + if (EXT2FS_CLUSTER_RATIO(fs) == 1) { + *freed += free_count; + while (free_count-- > 0) + ext2fs_block_alloc_stats2(fs, free_start++, -1); + return retval; + } + + /* + * Try to free up to the next cluster boundary. We assume that all + * blocks in a logical cluster map to blocks from the same physical + * cluster, and that the offsets within the [pl]clusters match. + */ + if (free_start & EXT2FS_CLUSTER_MASK(fs)) { + retval = ext2fs_map_cluster_block(fs, ino, inode, + lfree_start, &pblk); + if (retval) + goto errout; + if (!pblk) { + ext2fs_block_alloc_stats2(fs, free_start, -1); + freed_now++; + } + cluster_freed = EXT2FS_CLUSTER_RATIO(fs) - + (free_start & EXT2FS_CLUSTER_MASK(fs)); + if (cluster_freed > free_count) + cluster_freed = free_count; + free_count -= cluster_freed; + free_start += cluster_freed; + lfree_start += cluster_freed; + } + + /* Free whole clusters from the middle of the range. */ + while (free_count > 0 && free_count >= EXT2FS_CLUSTER_RATIO(fs)) { + ext2fs_block_alloc_stats2(fs, free_start, -1); + freed_now++; + cluster_freed = EXT2FS_CLUSTER_RATIO(fs); + free_count -= cluster_freed; + free_start += cluster_freed; + lfree_start += cluster_freed; + } + + /* Try to free the last cluster. */ + if (free_count > 0) { + retval = ext2fs_map_cluster_block(fs, ino, inode, + lfree_start, &pblk); + if (retval) + goto errout; + if (!pblk) { + ext2fs_block_alloc_stats2(fs, free_start, -1); + freed_now++; + } + } + +errout: + *freed += freed_now; + return retval; +} + static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, blk64_t start, blk64_t end) @@ -184,7 +253,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, ext2_extent_handle_t handle = 0; struct ext2fs_extent extent; errcode_t retval; - blk64_t free_start, next; + blk64_t free_start, next, lfree_start; __u32 free_count, newlen; int freed = 0; int op; @@ -211,6 +280,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, /* Start of deleted region before extent; adjust beginning of extent */ free_start = extent.e_pblk; + lfree_start = extent.e_lblk; if (next > end) free_count = end - extent.e_lblk + 1; else @@ -226,6 +296,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, dbg_printf("Case #%d\n", 2); newlen = start - extent.e_lblk; free_start = extent.e_pblk + newlen; + lfree_start = extent.e_lblk + newlen; free_count = extent.e_len - newlen; extent.e_len = newlen; } else { @@ -241,6 +312,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, extent.e_len = start - extent.e_lblk; free_start = extent.e_pblk + extent.e_len; + lfree_start = extent.e_lblk + extent.e_len; free_count = end - start + 1; dbg_print_extent("inserting", &newex); @@ -281,10 +353,10 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, goto errout; dbg_printf("Free start %llu, free count = %u\n", free_start, free_count); - while (free_count-- > 0) { - ext2fs_block_alloc_stats2(fs, free_start++, -1); - freed++; - } + retval = punch_extent_blocks(fs, ino, inode, lfree_start, + free_start, free_count, &freed); + if (retval) + goto errout; next_extent: retval = ext2fs_extent_get(handle, op, &extent);