- 19 Jun, 2014 9 commits
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Miao Xie authored
The original bio might be submitted, so we shoud increase bi_remaining to account for it when we deal with the error that the device is missing or is not writeable, or we would skip the endio handle. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Miao Xie authored
The deadlock happened when we mount degraded filesystem, the reproduced steps are following: # mkfs.btrfs -f -m raid1 -d raid1 <dev0> <dev1> # echo 1 > /sys/block/`basename <dev0>`/device/delete # mount -o degraded <dev1> <mnt> The reason was that the counter -- bi_remaining was wrong. If the missing or unwriteable device was the last device in the mapping array, we would not submit the original bio, so we shouldn't increase bi_remaining of it in btrfs_end_bio(), or we would skip the final endio handle. Fix this problem by adding a flag into btrfs bio structure. If we submit the original bio, we will set the flag, and we increase bi_remaining counter, or we don't. Though there is another way to fix it -- decrease bi_remaining counter of the original bio when we make sure the original bio is not submitted, this method need add more check and is easy to make mistake. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
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Miao Xie authored
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Wang Shilong authored
While running balance, scrub, fsstress concurrently we hit the following kernel crash: [56561.448845] BTRFS info (device sde): relocating block group 11005853696 flags 132 [56561.524077] BUG: unable to handle kernel NULL pointer dereference at 0000000000000078 [56561.524237] IP: [<ffffffffa038956d>] scrub_chunk.isra.12+0xdd/0x130 [btrfs] [56561.524297] PGD 9be28067 PUD 7f3dd067 PMD 0 [56561.524325] Oops: 0000 [#1] SMP [....] [56561.527237] Call Trace: [56561.527309] [<ffffffffa038980e>] scrub_enumerate_chunks+0x24e/0x490 [btrfs] [56561.527392] [<ffffffff810abe00>] ? abort_exclusive_wait+0x50/0xb0 [56561.527476] [<ffffffffa038add4>] btrfs_scrub_dev+0x1a4/0x530 [btrfs] [56561.527561] [<ffffffffa0368107>] btrfs_ioctl+0x13f7/0x2a90 [btrfs] [56561.527639] [<ffffffff811c82f0>] do_vfs_ioctl+0x2e0/0x4c0 [56561.527712] [<ffffffff8109c384>] ? vtime_account_user+0x54/0x60 [56561.527788] [<ffffffff810f768c>] ? __audit_syscall_entry+0x9c/0xf0 [56561.527870] [<ffffffff811c8551>] SyS_ioctl+0x81/0xa0 [56561.527941] [<ffffffff815707f7>] tracesys+0xdd/0xe2 [...] [56561.528304] RIP [<ffffffffa038956d>] scrub_chunk.isra.12+0xdd/0x130 [btrfs] [56561.528395] RSP <ffff88004c0f5be8> [56561.528454] CR2: 0000000000000078 This is because in btrfs_relocate_chunk(), we will free @bdev directly while scrub may still hold extent mapping, and may access freed memory. Fix this problem by wrapping freeing @bdev work into free_extent_map() which is based on reference count. Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Qu Wenruo authored
When run scrub with balance, sometimes -ENOENT will be returned, since in scrub_enumerate_chunks() will search dev_extent in *COMMIT_ROOT*, but btrfs_lookup_block_group() will search block group in *MEMORY*, so if a chunk is removed but not committed, -ENOENT will be returned. However, there is no need to stop scrubbing since other chunks may be scrubbed without problem. So this patch changes the behavior to skip removed chunks and continue to scrub the rest. Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Miao Xie authored
When we mounted the filesystem after the crash, we got the following message: BTRFS error (device xxx): block group xxxx has wrong amount of free space BTRFS error (device xxx): failed to load free space cache for block group xxx It is because we didn't update the metadata of the allocated space (in extent tree) until the file data was written into the disk. During this time, there was no information about the allocated spaces in either the extent tree nor the free space cache. when we wrote out the free space cache at this time (commit transaction), those spaces were lost. In fact, only the free space that is used to store the file data had this problem, the others didn't because the metadata of them is updated in the same transaction context. There are many methods which can fix the above problem - track the allocated space, and write it out when we write out the free space cache - account the size of the allocated space that is used to store the file data, if the size is not zero, don't write out the free space cache. The first one is complex and may make the performance drop down. This patch chose the second method, we use a per-block-group variant to account the size of that allocated space. Besides that, we also introduce a per-block-group read-write semaphore to avoid the race between the allocation and the free space cache write out. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Miao Xie authored
This patch makes the free space cache write out functions more readable, and beisdes that, it also reduces the stack space that the function -- __btrfs_write_out_cache uses from 194bytes to 144bytes. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
The lock_wq wait queue is not used anywhere, therefore just remove it. On a x86_64 system, this reduced sizeof(struct extent_buffer) from 320 bytes down to 296 bytes, which means a 4Kb page can now be used for 13 extent buffers instead of 12. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Chris Mason authored
The Btrfs tree trylock function is poorly named. It always takes the spinlock and backs off if the blocking lock is held. This can lead to surprising lockups because people expect it to really be a trylock. This commit makes it a pure trylock, both for the spinlock and the blocking lock. It also reworks the nested lock handling slightly to avoid taking the read lock while a spinning write lock might be held. Signed-off-by: Chris Mason <clm@fb.com>
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- 13 Jun, 2014 13 commits
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Eric Sandeen authored
fcebe456 cut and pasted some code to a later point in create_pending_snapshot(), but didn't switch to the appropriate error handling for this stage of the function. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Chris Mason <clm@fb.com>
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Eric Sandeen authored
If this condition in end_extent_writepage() is false: if (tree->ops && tree->ops->writepage_end_io_hook) we will then test an uninitialized "ret" at: ret = ret < 0 ? ret : -EIO; The test for ret is for the case where ->writepage_end_io_hook failed, and we'd choose that ret as the error; but if there is no ->writepage_end_io_hook, nothing sets ret. Initializing ret to 0 should be sufficient; if writepage_end_io_hook wasn't set, (!uptodate) means non-zero err was passed in, so we choose -EIO in that case. Signed-of-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Chris Mason <clm@fb.com>
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Eric Sandeen authored
If tmp = ulist_alloc(GFP_NOFS) fails, we return without freeing the previously allocated qgroups = ulist_alloc(GFP_NOFS) and cause a memory leak. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
Often when running the qgroups sanity test, a crash or a hang happened. This is because the extent buffer the test uses for the root node doesn't have an header level explicitly set, making it have a random level value. This is a problem when it's not zero for the btrfs_search_slot() calls the test ends up doing, resulting in crashes or hangs such as the following: [ 6454.127192] Btrfs loaded, debug=on, assert=on, integrity-checker=on (...) [ 6454.127760] BTRFS: selftest: Running qgroup tests [ 6454.127964] BTRFS: selftest: Running test_test_no_shared_qgroup [ 6454.127966] BTRFS: selftest: Qgroup basic add [ 6480.152005] BUG: soft lockup - CPU#0 stuck for 23s! [modprobe:5383] [ 6480.152005] Modules linked in: btrfs(+) xor raid6_pq binfmt_misc nfsd auth_rpcgss oid_registry nfs_acl nfs lockd fscache sunrpc i2c_piix4 i2c_core pcspkr evbug psmouse serio_raw e1000 [last unloaded: btrfs] [ 6480.152005] irq event stamp: 188448 [ 6480.152005] hardirqs last enabled at (188447): [<ffffffff8168ef5c>] restore_args+0x0/0x30 [ 6480.152005] hardirqs last disabled at (188448): [<ffffffff81698e6a>] apic_timer_interrupt+0x6a/0x80 [ 6480.152005] softirqs last enabled at (188446): [<ffffffff810516cf>] __do_softirq+0x1cf/0x450 [ 6480.152005] softirqs last disabled at (188441): [<ffffffff81051c25>] irq_exit+0xb5/0xc0 [ 6480.152005] CPU: 0 PID: 5383 Comm: modprobe Not tainted 3.15.0-rc8-fdm-btrfs-next-33+ #4 [ 6480.152005] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 6480.152005] task: ffff8802146125a0 ti: ffff8800d0d00000 task.ti: ffff8800d0d00000 [ 6480.152005] RIP: 0010:[<ffffffff81349a63>] [<ffffffff81349a63>] __write_lock_failed+0x13/0x20 [ 6480.152005] RSP: 0018:ffff8800d0d038e8 EFLAGS: 00000287 [ 6480.152005] RAX: 0000000000000000 RBX: ffffffff8168ef5c RCX: 000005deb8525852 [ 6480.152005] RDX: 0000000000000000 RSI: 0000000000001d45 RDI: ffff8802105000b8 [ 6480.152005] RBP: ffff8800d0d038e8 R08: fffffe12710f63db R09: ffffffffa03196fb [ 6480.152005] R10: ffff8802146125a0 R11: ffff880214612e28 R12: ffff8800d0d03858 [ 6480.152005] R13: 0000000000000000 R14: ffff8800d0d00000 R15: ffff8802146125a0 [ 6480.152005] FS: 00007f14ff804700(0000) GS:ffff880215e00000(0000) knlGS:0000000000000000 [ 6480.152005] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 6480.152005] CR2: 00007fff4df0dac8 CR3: 00000000d1796000 CR4: 00000000000006f0 [ 6480.152005] Stack: [ 6480.152005] ffff8800d0d03908 ffffffff810ae967 0000000000000001 ffff8802105000b8 [ 6480.152005] ffff8800d0d03938 ffffffff8168e57e ffffffffa0319c16 0000000000000007 [ 6480.152005] ffff880210500000 ffff880210500100 ffff8800d0d039b8 ffffffffa0319c16 [ 6480.152005] Call Trace: [ 6480.152005] [<ffffffff810ae967>] do_raw_write_lock+0x47/0xa0 [ 6480.152005] [<ffffffff8168e57e>] _raw_write_lock+0x5e/0x80 [ 6480.152005] [<ffffffffa0319c16>] ? btrfs_tree_lock+0x116/0x270 [btrfs] [ 6480.152005] [<ffffffffa0319c16>] btrfs_tree_lock+0x116/0x270 [btrfs] [ 6480.152005] [<ffffffffa02b2acb>] btrfs_lock_root_node+0x3b/0x50 [btrfs] [ 6480.152005] [<ffffffffa02b81a6>] btrfs_search_slot+0x916/0xa20 [btrfs] [ 6480.152005] [<ffffffff811a727f>] ? create_object+0x23f/0x300 [ 6480.152005] [<ffffffffa02b9958>] btrfs_insert_empty_items+0x78/0xd0 [btrfs] [ 6480.152005] [<ffffffffa036041a>] insert_normal_tree_ref.constprop.4+0xa2/0x19a [btrfs] [ 6480.152005] [<ffffffffa03605c3>] test_no_shared_qgroup+0xb1/0x1ca [btrfs] [ 6480.152005] [<ffffffff8108cad6>] ? local_clock+0x16/0x30 [ 6480.152005] [<ffffffffa035ef8e>] btrfs_test_qgroups+0x1ae/0x1d7 [btrfs] [ 6480.152005] [<ffffffffa03a69d2>] ? ftrace_define_fields_btrfs_space_reservation+0xfd/0xfd [btrfs] [ 6480.152005] [<ffffffffa03a6a86>] init_btrfs_fs+0xb4/0x153 [btrfs] [ 6480.152005] [<ffffffff81000352>] do_one_initcall+0x102/0x150 [ 6480.152005] [<ffffffff8103d223>] ? set_memory_nx+0x43/0x50 [ 6480.152005] [<ffffffff81682668>] ? set_section_ro_nx+0x6d/0x74 [ 6480.152005] [<ffffffff810d91cc>] load_module+0x1cdc/0x2630 (...) Therefore initialize the extent buffer as an empty leaf (level 0). Issue easy to reproduce when btrfs is built as a module via: $ for ((i = 1; i <= 1000000; i++)); do rmmod btrfs; modprobe btrfs; done Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Sasha Levin authored
Mark the dereference as protected by lock. Not doing so triggers an RCU warning since the radix tree assumed that RCU is in use. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
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Wang Shilong authored
Steps to reproduce: # mkfs.btrfs -f /dev/sd[b-f] -m raid5 -d raid5 # mkfs.ext4 /dev/sdc --->corrupt one of btrfs device # mount /dev/sdb /mnt -o degraded # btrfs scrub start -BRd /mnt This is because readahead would skip missing device, this is not true for RAID5/6, because REQ_GET_READ_MIRRORS return 1 for RAID5/6 block mapping. If expected data locates in missing device, readahead thread would not call __readahead_hook() which makes event @rc->elems=0 wait forever. Fix this problem by checking return value of btrfs_map_block(),we can only skip missing device safely if there are several mirrors. Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Gerhard Heift authored
This new ioctl call allows the user to supply a buffer of varying size in which a tree search can store its results. This is much more flexible if you want to receive items which are larger than the current fixed buffer of 3992 bytes or if you want to fetch more items at once. Items larger than this buffer are for example some of the type EXTENT_CSUM. Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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Gerhard Heift authored
By copying each found item seperatly to userspace, we do not need extra buffer in the kernel. Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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Gerhard Heift authored
This new function reads the content of an extent directly to user memory. Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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Gerhard Heift authored
If an item in tree_search is too large to be stored in the given buffer, return the needed size (including the header). Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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Gerhard Heift authored
In copy_to_sk, if an item is too large for the given buffer, it now returns -EOVERFLOW instead of copying a search_header with len = 0. For backward compatibility for the first item it still copies such a header to the buffer, but not any other following items, which could have fitted. tree_search changes -EOVERFLOW back to 0 to behave similiar to the way it behaved before this patch. Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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Gerhard Heift authored
rewrite search_ioctl to accept a buffer with varying size Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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Gerhard Heift authored
If the amount of items reached the given limit of nr_items, we can leave copy_to_sk without updating the key. Also by returning 1 we leave the loop in search_ioctl without rechecking if we reached the given limit. Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
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- 10 Jun, 2014 18 commits
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Chris Mason authored
The new call is smp_mb__{before,after}_atomic. The __ gives us extra protection from the atomic rays. Signed-off-by: Chris Mason <clm@fb.com>
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Liu Bo authored
The skinny extents are intepreted incorrectly in scrub_print_warning(), and end up hitting the BUG() in btrfs_extent_inline_ref_size. Reported-by: Konstantinos Skarlatos <k.skarlatos@gmail.com> Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
When cloning into a file, we were correctly replacing the extent items in the target range and removing the extent maps. However we weren't replacing the extent maps with new ones that point to the new extents - as a consequence, an incremental fsync (when the inode doesn't have the full sync flag) was a NOOP, since it relies on the existence of extent maps in the modified list of the inode's extent map tree, which was empty. Therefore add new extent maps to reflect the target clone range. A test case for xfstests follows. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Liu Bo authored
We want to make sure the point is still within the extent item, not to verify the memory it's pointing to. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
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Josef Bacik authored
The backref code was looking at nodes as well as leaves when we tried to populate extent item entries. This is not good, and although we go away with it for the most part because we'd skip where disk_bytenr != random_memory, sometimes random_memory would match and suddenly boom. This fixes that problem. Thanks, Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
In inode.c:btrfs_page_exists_in_range(), if the page we got from the radix tree is an exception entry, which can't be retried, we exit the loop with a non-NULL page and then call page_cache_release against it, which is not ok since it's not a valid page. This could also make us return true when we shouldn't. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
In inode.c:btrfs_page_exists_in_range(), if the page we get from the radix tree is an exception which should make us retry, set page to NULL in order to really retry, because otherwise we don't get another loop iteration executed (page != NULL makes the while loop exit). This also was making us call page_cache_release after exiting the loop, which isn't correct because page doesn't point to a valid page, and possibly return true from the function when we shouldn't. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
In inode.c:btrfs_page_exists_in_range(), if we can't get the page we need to retry. However we weren't retrying because we weren't setting page to NULL, which makes the while loop exit immediately and will make us call page_cache_release after exiting the loop which is incorrect because our page get didn't succeed. This could also make us return true when we shouldn't. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Gui Hecheng authored
To return EOPNOTSUPP is more user friendly than to return EINVAL, and then user-space tool will show that the dev_replace operation for raid56 is not currently supported rather than showing that there is an invalid argument. Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Antonio Ospite authored
Signed-off-by: Antonio Ospite <ao2@ao2.it> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <jbacik@fb.com> Cc: linux-btrfs@vger.kernel.org Signed-off-by: Chris Mason <clm@fb.com>
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Liu Bo authored
Several reports about leaf corruption has been floating on the list, one of them points to __btrfs_drop_extents(), and we find that the leaf becomes corrupted after __btrfs_drop_extents(), it's really a rare case but it does exist. The problem turns out to be btrfs_next_leaf() called in __btrfs_drop_extents(). So in btrfs_next_leaf(), we release the current path to re-search the last key of the leaf for locating next leaf, and we've taken it into account that there might be balance operations between leafs during this 'unlock and re-lock' dance, so we check the path again and advance it if there are now more items available. But things are a bit different if that last key happens to be removed and balance gets a bigger key as the last one, and btrfs_search_slot will return it with ret > 0, IOW, nothing change in this leaf except the new last key, then we think we're okay because there is no more item balanced in, fine, we thinks we can go to the next leaf. However, we should return that bigger key, otherwise we deserve leaf corruption, for example, in endio, skipping that key means that __btrfs_drop_extents() thinks it has dropped all extent matched the required range and finish_ordered_io can safely insert a new extent, but it actually doesn't and ends up a leaf corruption. One may be asking that why our locking on extent io tree doesn't work as expected, ie. it should avoid this kind of race situation. But in __btrfs_drop_extents(), we don't always find extents which are included within our locking range, IOW, extents can start before our searching start, in this case locking on extent io tree doesn't protect us from the race. This takes the special case into account. Reviewed-by: Filipe Manana <fdmanana@gmail.com> Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
We might have had an item with the previous key in the tree right before we released our path. And after we released our path, that item might have been pushed to the first slot (0) of the leaf we were holding due to a tree balance. Alternatively, an item with the previous key can exist as the only element of a leaf (big fat item). Therefore account for these 2 cases, so that our callers (like btrfs_previous_item) don't miss an existing item with a key matching the previous key we computed above. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
If the NO_HOLES feature is enabled holes don't have file extent items in the btree that represent them anymore. This made the clone operation ignore the gaps that exist between consecutive file extent items and therefore not create the holes at the destination. When not using the NO_HOLES feature, the holes were created at the destination. A test case for xfstests follows. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
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Jeff Mahoney authored
On heavy workloads, we're seeing soft lockup warnings on root->inode_lock in __btrfs_release_delayed_node. The low hanging fruit is to reduce the size of the critical section. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <clm@fb.com>
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Gui Hecheng authored
To be accurate about the error case, if the new size is beyond ULLONG_MAX, return ERANGE instead of EINVAL. Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
If btrfs_log_dentry_safe() returns an error, we set ret to 1 and fall through with the goal of committing the transaction. However, in the case where the inode doesn't need a full sync, we would call btrfs_wait_ordered_range() against the target range for our inode, and if it returned an error, we would return without commiting or ending the transaction. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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Qu Wenruo authored
btrfs_punch_hole() will truncate unaligned pages or punch hole on a already existed hole. This will cause unneeded zero page or holes splitting the original huge hole. This patch will skip already existed holes before any page truncating or hole punching. Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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Filipe Manana authored
On snapshot creation (either writable or read-only), we do orphan cleanup against the root of the snapshot. If the cleanup did remove any orphans, then the current root node will be different from the commit root node until the next transaction commit happens. A send operation always uses the commit root of a snapshot - this means it will see the orphans if it starts computing the send stream before the next transaction commit happens (triggered by a timer or sync() for .e.g), which is when the commit root gets assigned a reference to current root, where the orphans are not visible anymore. The consequence of send seeing the orphans is explained below. For example: mkfs.btrfs -f /dev/sdd mount -o commit=999 /dev/sdd /mnt # open a file with O_TMPFILE and leave it open # write some data to the file btrfs subvolume snapshot -r /mnt /mnt/snap1 btrfs send /mnt/snap1 -f /tmp/send.data The send operation will fail with the following error: ERROR: send ioctl failed with -116: Stale file handle What happens here is that our snapshot has an orphan inode still visible through the commit root, that corresponds to the tmpfile. However send will attempt to call inode.c:btrfs_iget(), with the goal of reading the file's data, which will return -ESTALE because it will use the current root (and not the commit root) of the snapshot. Of course, there are other cases where we can get orphans, but this example using a tmpfile makes it much easier to reproduce the issue. Therefore on snapshot creation, after calling btrfs_orphan_cleanup, if the commit root is different from the current root, just commit the transaction associated with the snapshot's root (if it exists), so that a send will not see any orphans that don't exist anymore. This also guarantees a send will always see the same content regardless of whether a transaction commit happened already before the send was requested and after the orphan cleanup (meaning the commit root and current roots are the same) or it hasn't happened yet (commit and current roots are different). Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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