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* ext4: remove useless marking of superblock dirtyJan Kara2012-07-231-2/+0
| | | | | | | | | | | | | | Commit a0375156 properly notes that superblock doesn't need to be marked as dirty when only number of free inodes / blocks / number of directories changes since that is recomputed on each mount anyway. However that comment leaves some unnecessary markings as dirty in place. Remove these. Artem: tested using xfstests for both journalled and non-journalled ext4. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
* ext4: remove an unused statement in ext4_mb_get_buddy_page_lock()Haibo Liu2012-07-091-1/+0
| | | | | | | | | | | In this patch, the statement "poff = block % blocks_per_page" in ext4_mb_get_buddy_page_lock has no effect. It will be optimized out by the compiler, but it's better to remove it. Signed-off-by: Haibo Liu <HaiboLiu6@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: avoid uneeded calls to ext4_mb_load_buddy() while reading mb_groupsAditya Kali2012-07-011-8/+15
| | | | | | | | | | | | | | | | | | Currently ext4_mb_load_buddy is called for every group, irrespective of whether the group info is already in memory, while reading /proc/fs/ext4/<partition>/mb_groups proc file. For the purpose of mb_groups proc file, it is unnecessary to load the file group info from disk if it was loaded in past. These calls to ext4_mb_load_buddy make reading the mb_groups proc file expensive. Also, the locks around ext4_get_group_info are not required. This patch modifies the code to call ext4_mb_load_buddy only if the group info had never been loaded into memory in past. It also removes the mb group locking around ext4_get_group_info call. Signed-off-by: Aditya Kali <adityakali@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove mb_groups before tearing down the buddy_cacheSalman Qazi2012-06-011-2/+3
| | | | | | | | | | | | | | | | | | We can't have references held on pages in the s_buddy_cache while we are trying to truncate its pages and put the inode. All the pages must be gone before we reach clear_inode. This can only be gauranteed if we can prevent new users from grabbing references to s_buddy_cache's pages. The original bug can be reproduced and the bug fix can be verified by: while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \ umount /export/hda3/ram0; done & while true; do cat /proc/fs/ext4/ram0/mb_groups; done Signed-off-by: Salman Qazi <sqazi@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
* ext4: add ext4_mb_unload_buddy in the error pathSalman Qazi2012-06-011-0/+1
| | | | | | | | | ext4_free_blocks fails to pair an ext4_mb_load_buddy with a matching ext4_mb_unload_buddy when it fails a memory allocation. Signed-off-by: Salman Qazi <sqazi@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
* ext4: cleanup in ext4_discard_allocated_blocks()Zheng Liu2012-05-281-6/+2
| | | | | | | | remove 'len' variable in ext4_discard_allocated_blocks() because it is useless. Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove needs_recovery in ext4_mb_init()Akira Fujita2012-05-281-1/+1
| | | | | | | needs_recovery in ext4_mb_init() is not used, remove it. Signed-off-by: Akira Fujita <a-fujita@rs.jp.ne.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: make block group checksums use metadata_csum algorithmDarrick J. Wong2012-04-301-3/+3
| | | | | | | | | | | metadata_csum supersedes uninit_bg. Convert the ROCOMPAT uninit_bg flag check to a helper function that covers both, and make the checksum calculation algorithm use either crc16 or the metadata_csum chosen algorithm depending on which flag is set. Print a warning if we try to mount a filesystem with both feature flags set. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: calculate and verify block bitmap checksumDarrick J. Wong2012-04-301-1/+7
| | | | | | | | Compute and verify the checksum of the block bitmap; this checksum is stored in the block group descriptor. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: always set then trimmed blocks count into lenLukas Czerner2012-03-221-1/+1
| | | | | | | | | | | | | | Currently if the range to trim is too small, for example on 1K fs the request to trim the first block, then the 'range->len' is not set reporting wrong number of discarded block to the caller. Fix this by always setting the 'range->len' before we return. Note that when there is a failure (-EINVAL) caller can not depend on 'range->len' being set properly. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix trimmed block count accuntingLukas Czerner2012-03-221-1/+1
| | | | | | | | | | | | Currently when there is not enough free blocks in the block group to discard (grp->bb_free < minlen) the 'trimmed' is bumped up anyway with the number of discarded blocks from the previous iteration. Fix this by bumping up 'trimmed' only if the ext4_trim_all_free() was actually run. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix start and len arguments handling in ext4_trim_fs()Lukas Czerner2012-03-221-27/+30
| | | | | | | | | | | | | | | | | | The overflow can happen when we are calling get_group_no_and_offset() which stores the group number in the ext4_grpblk_t type which is actually int. However when the blocknr is big enough the group number might be bigger than ext4_grpblk_t resulting in overflow. This will most likely happen with FITRIM default argument len = ULLONG_MAX. Fix this by using "end" variable instead of "start+len" as it is easier to get right and specifically check that the end is not beyond the end of the file system, so we are sure that the result of get_group_no_and_offset() will not overflow. Otherwise truncate it to the size of the file system. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove trailing newlines from ext4_msg() and ext4_error() messagesTheodore Ts'o2012-03-201-1/+1
| | | | | | | | | The functions ext4_msg() and ext4_error() already tack on a trailing newline, so remove the unnecessary extra newline. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove redundant "EXT4-fs: " from uses of ext4_msgJoe Perches2012-03-201-7/+7
| | | | | | | | ext4_msg adds "EXT4-fs: " to the messsage output. Remove the redundant bits from uses. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove EXT4_MB_{BITMAP,BUDDY} macrosTheodore Ts'o2012-02-201-16/+16
| | | | | | | The EXT4_MB_BITMAP and EXT4_MB_BUDDY macros obfuscate more than they provide any abstraction. So remove them. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: mark possibly unused variable in ext4_mb_normalize_request()Curt Wohlgemuth2012-02-201-1/+2
| | | | | | | | The 'orig_size' local variable is only used in a call to mb_debug(). Mark it with '__maybe_unused'. Signed-off-by: Curt Wohlgemuth <curtw@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: expand commit callback andBobi Jam2012-02-201-80/+71
| | | | | | | | | | | The per-commit callback was used by mballoc code to manage free space bitmaps after deleted blocks have been released. This patch expands it to support multiple different callbacks, to allow other things to be done after the commit has been completed. Signed-off-by: Bobi Jam <bobijam@whamcloud.com> Signed-off-by: Andreas Dilger <adilger@whamcloud.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix race when setting bitmap_uptodate flagTheodore Ts'o2012-02-201-64/+15
| | | | | | | | | | | | | | In ext4_read_{inode,block}_bitmap() we were setting bitmap_uptodate() before submitting the buffer for read. The is bad, since we check bitmap_uptodate() without locking the buffer, and so if another process is racing with us, it's possible that they will think the bitmap is uptodate even though the read has not completed yet, resulting in inodes and blocks potentially getting allocated more than once if we get really unlucky. Addresses-Google-Bug: 2828254 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: do not reference pa_inode from group_paYongqiang Yang2011-12-181-1/+1
| | | | | | | | | pa_inode in group_pa is set NULL in ext4_mb_new_group_pa, so pa_inode should be not referenced. Reported-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix a wrong comment in __mb_check_buddy()Robin Dong2011-10-261-1/+1
| | | | | | | | The comment says the bit should be 0, but the after code assert the bit to be 1. This makes people confused, so fix it. Signed-off-by: Robin Dong <sanbai@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove unused variable in mb_find_extent()Robin Dong2011-10-261-3/+1
| | | | | | | | The variable 'ord' in function mb_find_extent() is redundant, so remove it. Signed-off-by: Robin Dong <sanbai@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove unused variable in ext4_mb_generate_from_pa()Robin Dong2011-10-261-2/+0
| | | | | | | | The variable 'count' in function ext4_mb_generate_from_pa() looks useless, so remove it. Signed-off-by: Robin Dong <sanbai@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use stream-alloc when mb_group_prealloc set to zeroRobin Dong2011-10-261-0/+5
| | | | | | | | | | | | | | | | | | The kernel will crash on ext4_mb_mark_diskspace_used: BUG_ON(ac->ac_b_ex.fe_len <= 0); after we set /sys/fs/ext4/sda/mb_group_prealloc to zero and create new files in an ext4 filesystem. The reason is: ac_b_ex.fe_len also set to zero(mb_group_prealloc) in ext4_mb_normalize_group_request because the ac_flags contains EXT4_MB_HINT_GROUP_ALLOC. I think when someone set mb_group_prealloc to zero, it means DO NOT USE GROUP PREALLOCATION, so we should set alloc-strategy to STREAM in this case. Signed-off-by: Robin Dong <sanbai@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Allow quota file use root reservationDmitry Monakhov2011-10-211-0/+4
| | | | | | | | Quota file is fs's metadata, so it is reasonable to permit use root resevation if necessary. This patch fix 265'th xfstest failure Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Free resources in ext4_mb_init()'s error pathsTao Ma2011-10-061-8/+15
| | | | | | | | | | | In commit 79a77c5ac, we move ext4_mb_init_backend after the allocation of s_locality_group to avoid memory leak in error path, but there are still some other error paths in ext4_mb_init that need to do the same work. So this patch adds all the error patch for ext4_mb_init. And all the pointers are reset to NULL in case the caller may double free them. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: rename ext4_claim_free_blocks() to ext4_claim_free_clusters()Theodore Ts'o2011-09-101-1/+1
| | | | | | | This function really claims a number of free clusters, not blocks, so rename it so it's clearer what's going on. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: rename ext4_free_blocks_after_init() to ext4_free_clusters_after_init()Theodore Ts'o2011-09-101-2/+2
| | | | | | | This function really returns the number of clusters after initializing an uninitalized block bitmap has been initialized. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Rename ext4_free_blks_{count,set}() to refer to clustersTheodore Ts'o2011-09-101-11/+11
| | | | | | | | | | | | | The field bg_free_blocks_count_{lo,high} in the block group descriptor has been repurposed to hold the number of free clusters for bigalloc functions. So rename the functions so it makes it easier to read and audit the block allocation and block freeing code. Note: at this point in bigalloc development we doesn't support online resize, so this also makes it really obvious all of the places we need to fix up to add support for online resize. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Fix bigalloc quota accounting and i_blocks valueAditya Kali2011-09-101-2/+3
| | | | | | | | | | | With bigalloc changes, the i_blocks value was not correctly set (it was still set to number of blocks being used, but in case of bigalloc, we want i_blocks to represent the number of clusters being used). Since the quota subsystem sets the i_blocks value, this patch fixes the quota accounting and makes sure that the i_blocks value is set correctly. Signed-off-by: Aditya Kali <adityakali@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: tune mballoc's default group prealloc size for bigalloc file systemsTheodore Ts'o2011-09-101-2/+16
| | | | | | | | | The default group preallocation size had been previously set to 512 blocks/clusters, regardless of the block/cluster size. This is probably too big for large cluster sizes. So adjust the default so that it is 2 megabytes or 32 clusters, whichever is larger. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: convert the free_blocks field in s_flex_groups to be free_clustersTheodore Ts'o2011-09-101-4/+5
| | | | | | | | | Convert the free_blocks to be free_clusters to make the final revised bigalloc changes easier to read/understand. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: convert s_{dirty,free}blocks_counter to s_{dirty,free}clusters_counterTheodore Ts'o2011-09-101-5/+7
| | | | | | | | Convert the percpu counters s_dirtyblocks_counter and s_freeblocks_counter in struct ext4_super_info to be s_dirtyclusters_counter and s_freeclusters_counter. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: teach ext4_free_blocks() about bigalloc and clustersTheodore Ts'o2011-09-101-24/+62
| | | | | | | | | | | | | | The ext4_free_blocks() function now has two new flags that indicate whether a partial cluster at the beginning or the end of the block extents should be freed or not. That will be up the caller (i.e., truncate), who can figure out whether partial clusters at the beginning or the end of a block range can be freed. We also have to update the ext4_mb_free_metadata() and release_blocks_on_commit() machinery to be cluster-based, since it is used by ext4_free_blocks(). Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: teach mballoc preallocation code about bigalloc clustersTheodore Ts'o2011-09-101-41/+54
| | | | | | | | | | | | | | | In most of mballoc.c, we do everything in units of clusters, since the block allocation bitmaps and buddy bitmaps are all denominated in clusters. The one place where we do deal with absolute block numbers is in the code that handles the preallocation regions, since in the case of inode-based preallocation regions, the start of the preallocation region can't be relative to the beginning of the group. So this adds a bit of complexity, where pa_pstart and pa_lstart are block numbers, while pa_free, pa_len, and fe_len are denominated in units of clusters. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: convert instances of EXT4_BLOCKS_PER_GROUP to EXT4_CLUSTERS_PER_GROUPTheodore Ts'o2011-09-101-24/+24
| | | | | | | | | | | | Change the places in fs/ext4/mballoc.c where EXT4_BLOCKS_PER_GROUP are used to indicate the number of bits in a block bitmap (which is really a cluster allocation bitmap in bigalloc file systems). There are still some places in the ext4 codebase where usage of EXT4_BLOCKS_PER_GROUP needs to be audited/fixed, in code paths that aren't used given the initial restricted assumptions for bigalloc. These will need to be fixed before we can relax those restrictions. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: prevent memory leaks from ext4_mb_init_backend() on error pathYu Jian2011-08-011-6/+6
| | | | | | | | | | | In ext4_mb_init(), if the s_locality_group allocation fails it will currently cause the allocations made in ext4_mb_init_backend() to be leaked. Moving the ext4_mb_init_backend() allocation after the s_locality_group allocation avoids that problem. Signed-off-by: Yu Jian <yujian@whamcloud.com> Signed-off-by: Andreas Dilger <adilger@whamcloud.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use EXT4_BAD_INO for buddy cache to avoid colliding with valid inode #Yu Jian2011-08-011-1/+5
| | | | | | Signed-off-by: Yu Jian <yujian@whamcloud.com> Signed-off-by: Andreas Dilger <adilger@whamcloud.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use ext4_msg() instead of printk in mballocTheodore Ts'o2011-08-011-37/+42
| | | | Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: use ext4_kvzalloc()/ext4_kvmalloc() for s_group_desc and s_group_infoTheodore Ts'o2011-08-011-3/+3
| | | | Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: let setup_new_group_blocks() set multiple bits at a timeYongqiang Yang2011-07-271-7/+8
| | | | | | | | Rename mb_set_bits() to ext4_set_bits() and make it a global function so that setup_new_group_blocks() can use it. Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: let ext4_group_add_blocks() handle 0 blocks quicklyYongqiang Yang2011-07-271-0/+3
| | | | | | | | If ext4_group_add_blocks() is called with 0 block, make it return 0 without doing any extra work. Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: let ext4_group_add_blocks() return an error codeYongqiang Yang2011-07-271-5/+15
| | | | | | | | This patch lets ext4_group_add_blocks() return an error code if it fails, so that upper functions can handle error correctly. Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: rename ext4_add_groupblocks() to ext4_group_add_blocks()Yongqiang Yang2011-07-271-2/+2
| | | | | Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: don't increment s_mb_buddies_generated in ext4_mb_releaseTao Ma2011-07-231-1/+1
| | | | | | | | In ext4_mb_release, we use s_mb_buddies_generated++. Although the output is OK, but I don't think we need this extra ++. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: remove unnecessary ext4_get_group_info in ext4_mb_load_buddyTao Ma2011-07-231-1/+1
| | | | | | | | | ext4_mb_load_buddy() calls ext4_get_group_info() for setting both "grp" and "e4b->bd_info", but it could do "e4b->bd_info = grp". Reported-by: Andreas Dilger <adilger@whamcloud.com> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: make the preallocation size be a multiple of stripe sizeDan Ehrenberg2011-07-181-9/+20
| | | | | | | | | | | | Previously, if a stripe width was provided, then it would be used as the preallocation granularity, with no santiy checking and no way to override this. Now, mb_prealloc_size defaults to the smallest multiple of stripe size that is greater than or equal to the old default mb_prealloc_size, and this can be overridden with the sysfs interface. Signed-off-by: Dan Ehrenberg <dehrenberg@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Fix a double free of sbi->s_group_info in ext4_mb_init_backendTao Ma2011-07-121-5/+7
| | | | | | | | | | | | If we meet with an error in ext4_mb_add_groupinfo, we kfree sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)], but fail to reset it to NULL. So the caller ext4_mb_init_backend will try to kfree it again and causes a double free. So fix it by resetting it to NULL. Some typo in comments of mballoc.c are also changed. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: fix a race which could leak memory in ext4_groupinfo_create_slab()Tao Ma2011-07-121-2/+2
| | | | | | | | | | In ext4_groupinfo_create_slab, we create ext4_groupinfo_caches within ext4_grpinfo_slab_create_mutex, but set it outside the lock, and there does exist some case that we may create it twice and causes a memory leak. So set it before we call mutex_unlock. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Change the wrong param comment for ext4_trim_all_freeTao Ma2011-07-111-1/+1
| | | | | | | | | at ext4_trim_all_free() comment, there is no longer an @e4b parameter, instead it is @group. Reported-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* ext4: Speed up FITRIM by recording flags in ext4_group_infoTao Ma2011-07-111-0/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In ext4, when FITRIM is called every time, we iterate all the groups and do trim one by one. It is a bit time wasting if the group has been trimmed and there is no change since the last trim. So this patch adds a new flag in ext4_group_info->bb_state to indicate that the group has been trimmed, and it will be cleared if some blocks is freed(in release_blocks_on_commit). Another trim_minlen is added in ext4_sb_info to record the last minlen we use to trim the volume, so that if the caller provide a small one, we will go on the trim regardless of the bb_state. A simple test with my intel x25m ssd: df -h shows: /dev/sdb1 40G 21G 17G 56% /mnt/ext4 Block size: 4096 run the FITRIM with the following parameter: range.start = 0; range.len = UINT64_MAX; range.minlen = 1048576; without the patch: [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a real 0m5.505s user 0m0.000s sys 0m1.224s [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a real 0m5.359s user 0m0.000s sys 0m1.178s [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a real 0m5.228s user 0m0.000s sys 0m1.151s with the patch: [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a real 0m5.625s user 0m0.000s sys 0m1.269s [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a real 0m0.002s user 0m0.000s sys 0m0.001s [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a real 0m0.002s user 0m0.000s sys 0m0.001s A big improvement for the 2nd and 3rd run. Even after I delete some big image files, it is still much faster than iterating the whole disk. [root@boyu-tm test]# time ./ftrim /mnt/ext4/a real 0m1.217s user 0m0.000s sys 0m0.196s Cc: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Andreas Dilger <adilger.kernel@dilger.ca> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>