From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:56058 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751781AbdKTRxD (ORCPT ); Mon, 20 Nov 2017 12:53:03 -0500 Date: Mon, 20 Nov 2017 18:51:06 +0100 From: David Sterba To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org, dsterba@suse.cz, lists@colorremedies.com Subject: Re: [PATCH] btrfs: Enhance btrfs_trim_fs function to handle error better Message-ID: <20171120175106.GE3553@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <20171120055651.17892-1-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20171120055651.17892-1-wqu@suse.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, Nov 20, 2017 at 01:56:51PM +0800, Qu Wenruo wrote: > Function btrfs_trim_fs() doesn't handle errors in a consistent way, if > error happens when trimming existing block groups, it will skip the > remaining blocks and continue to trim unallocated space for each device. > > And the return value will only reflect the final error from device > trimming. > > This patch will fix such behavior by: > > 1) Recording first error from block group or device trimming > So return value will also reflect any error found when trimming. > Make developer more aware of the problem. > > 2) Outputting btrfs warning message for each trimming failure > Any error for block group or device trimming will cause btrfs warning > kernel message. I think this could become too noisy, trimming failures are soft errors IMO, so it should be enough to report all errors cumulatively per-device. > 3) Continuing trimming if we can > If we failed to trim one block group or device, we could still try > next block group or device. Right, best-effort. > Such behavior can avoid confusion for case like failure to trim the > first block group and then only unallocated space is trimmed. > > Reported-by: Chris Murphy > Signed-off-by: Qu Wenruo > --- > fs/btrfs/extent-tree.c | 59 ++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 43 insertions(+), 16 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 309a109069f1..46d65ffb3bd1 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -10948,6 +10948,16 @@ static int btrfs_trim_free_extents(struct btrfs_device *device, > return ret; > } > > +/* > + * Trim the whole fs, by: > + * 1) Trimming free space in each block group > + * 2) Trimming unallocated space in each device > + * > + * Will try to continue trimming even if we failed to trim one block group or > + * device. > + * The return value will be the error return value of the first error. > + * Or 0 if nothing wrong happened. > + */ > int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) > { > struct btrfs_block_group_cache *cache = NULL; > @@ -10958,6 +10968,8 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) > u64 end; > u64 trimmed = 0; > u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy); > + int bg_ret = 0; > + int dev_ret = 0; > int ret = 0; > > /* > @@ -10968,7 +10980,7 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) > else > cache = btrfs_lookup_block_group(fs_info, range->start); > > - while (cache) { > + for (; cache; cache = next_block_group(fs_info, cache)) { > if (cache->key.objectid >= (range->start + range->len)) { > btrfs_put_block_group(cache); > break; > @@ -10982,29 +10994,36 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) > if (!block_group_cache_done(cache)) { > ret = cache_block_group(cache, 0); > if (ret) { > - btrfs_put_block_group(cache); > - break; > + btrfs_warn_rl(fs_info, > + "failed to cache block group %llu ret %d", If this is meant for a developer as you say in the changelog, then btrfs_debug is better. > + cache->key.objectid, ret); > + if (!bg_ret) > + bg_ret = ret; > + continue; > } > ret = wait_block_group_cache_done(cache); > if (ret) { > - btrfs_put_block_group(cache); > - break; > + btrfs_warn_rl(fs_info, > + "failed to wait cache for block group %llu ret %d", The message wording is confusing, if this is another message for developer, the function name can be printed. > + cache->key.objectid, ret); > + if (!bg_ret) > + bg_ret = ret; > + continue; > } > } > - ret = btrfs_trim_block_group(cache, > - &group_trimmed, > - start, > - end, > - range->minlen); > + ret = btrfs_trim_block_group(cache, &group_trimmed, > + start, end, range->minlen); > > trimmed += group_trimmed; > if (ret) { > - btrfs_put_block_group(cache); > - break; > + btrfs_warn_rl(fs_info, > + "failed to trim block group %llu ret %d", > + cache->key.objectid, ret); > + if (!bg_ret) > + bg_ret = ret; > + continue; > } > } > - > - cache = next_block_group(fs_info, cache); > } > > mutex_lock(&fs_info->fs_devices->device_list_mutex); > @@ -11012,15 +11031,23 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) > list_for_each_entry(device, devices, dev_alloc_list) { > ret = btrfs_trim_free_extents(device, range->minlen, > &group_trimmed); > - if (ret) > + if (ret) { > + btrfs_warn_rl(fs_info, > + "failed to trim unallocated space for devid %llu ret %d", > + device->devid, ret); So the idea is to print one message here, with devid, number of errors and how many bytes were skipped. > + if (!dev_ret) > + dev_ret = ret; > break; > + } > > trimmed += group_trimmed; > } > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > > range->len = trimmed; > - return ret; > + if (bg_ret) > + return bg_ret; > + return dev_ret; > } > > /* > -- > 2.15.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html