kernel/linux.git/fs/btrfs/dev-replace.c, branch v6.1.168

btrfs: dev-replace: properly validate device names

2024-03-06T14:45:10+00:00

commit 9845664b9ee47ce7ee7ea93caf47d39a9d4552c4 upstream. There's a syzbot report that device name buffers passed to device replace are not properly checked for string termination which could lead to a read out of bounds in getname_kernel(). Add a helper that validates both source and target device name buffers. For devid as the source initialize the buffer to empty string in case something tries to read it later. This was originally analyzed and fixed in a different way by Edward Adam Davis (see links). Link: https://lore.kernel.org/linux-btrfs/000000000000d1a1d1060cc9c5e7@google.com/ Link: https://lore.kernel.org/linux-btrfs/tencent_44CA0665C9836EF9EEC80CB9E7E206DF5206@qq.com/ CC: stable@vger.kernel.org # 4.19+ CC: Edward Adam Davis Reported-and-tested-by: syzbot+33f23b49ac24f986c9e8@syzkaller.appspotmail.com Reviewed-by: Boris Burkov Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

btrfs: don't take a bio_counter reference for cloned bios

2022-09-26T10:27:58+00:00

Stop grabbing an extra bio_counter reference for each clone bio in a mirrored write and instead just release the one original reference in btrfs_end_bioc once all the bios for a single btrfs_bio have completed instead of at the end of btrfs_submit_bio once all bios have been submitted. This means the reference is now carried by the "upper" btrfs_bio only instead of each lower bio. Also remove the now unused btrfs_bio_counter_inc_noblocked helper. Reviewed-by: Nikolay Borisov Reviewed-by: Johannes Thumshirn Reviewed-by: Anand Jain Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba

btrfs: remove lock protection for BLOCK_GROUP_FLAG_TO_COPY

2022-09-26T10:27:54+00:00

We use this during device replace for zoned devices, we were simply taking the lock because it was in a bit field and we needed the lock to be safe with other modifications in the bitfield. With the bit helpers we no longer require that locking. Reviewed-by: Johannes Thumshirn Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: convert block group bit field to use bit helpers

2022-09-26T10:27:54+00:00

We use a bit field in the btrfs_block_group for different flags, however this is awkward because we have to hold the block_group->lock for any modification of any of these fields, and makes the code clunky for a few of these flags. Convert these to a properly flags setup so we can utilize the bit helpers. Reviewed-by: Johannes Thumshirn Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: add info when mount fails due to stale replace target

2022-08-23T20:15:21+00:00

If the replace target device reappears after the suspended replace is cancelled, it blocks the mount operation as it can't find the matching replace-item in the metadata. As shown below, BTRFS error (device sda5): replace devid present without an active replace item To overcome this situation, the user can run the command btrfs device scan --forget and try the mount command again. And also, to avoid repeating the issue, superblock on the devid=0 must be wiped. wipefs -a device-path-to-devid=0. This patch adds some info when this situation occurs. Reported-by: Samuel Greiner Link: https://lore.kernel.org/linux-btrfs/b4f62b10-b295-26ea-71f9-9a5c9299d42c@balkonien.org/T/ CC: stable@vger.kernel.org # 5.0+ Signed-off-by: Anand Jain Signed-off-by: David Sterba

btrfs: replace: drop assert for suspended replace

2022-08-23T20:15:21+00:00

If the filesystem mounts with the replace-operation in a suspended state and try to cancel the suspended replace-operation, we hit the assert. The assert came from the commit fe97e2e173af ("btrfs: dev-replace: replace's scrub must not be running in suspended state") that was actually not required. So just remove it. $ mount /dev/sda5 /btrfs BTRFS info (device sda5): cannot continue dev_replace, tgtdev is missing BTRFS info (device sda5): you may cancel the operation after 'mount -o degraded' $ mount -o degraded /dev/sda5 /btrfs <-- success. $ btrfs replace cancel /btrfs kernel: assertion failed: ret != -ENOTCONN, in fs/btrfs/dev-replace.c:1131 kernel: ------------[ cut here ]------------ kernel: kernel BUG at fs/btrfs/ctree.h:3750! After the patch: $ btrfs replace cancel /btrfs BTRFS info (device sda5): suspended dev_replace from /dev/sda5 (devid 1) to canceled Fixes: fe97e2e173af ("btrfs: dev-replace: replace's scrub must not be running in suspended state") CC: stable@vger.kernel.org # 5.0+ Signed-off-by: Anand Jain Signed-off-by: David Sterba

btrfs: clean up chained assignments

2022-07-25T15:45:39+00:00

The chained assignments may be convenient to write, but make readability a bit worse as it's too easy to overlook that there are several values set on the same line while this is rather an exception. Making it consistent everywhere avoids surprises. The pattern where inode times are initialized reuses the first value and the order is mtime, ctime. In other blocks the assignments are expanded so the order of variables is similar to the neighboring code. Signed-off-by: David Sterba

btrfs: use a local variable for fs_devices pointer in btrfs_dev_replace_finishing

2022-05-16T15:03:08+00:00

In the function btrfs_dev_replace_finishing, we dereferenced fs_info->fs_devices 6 times. Use keep local variable for that. Reviewed-by: Johannes Thumshirn Signed-off-by: Anand Jain Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: use btrfs_for_each_slot in mark_block_group_to_copy

2022-05-16T15:03:07+00:00

This function can be simplified by refactoring to use the new iterator macro. No functional changes. Signed-off-by: Marcos Paulo de Souza Signed-off-by: Gabriel Niebler Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: fix assertion failure during scrub due to block group reallocation

2022-04-21T14:06:19+00:00

During a scrub, or device replace, we can race with block group removal and allocation and trigger the following assertion failure: [7526.385524] assertion failed: cache->start == chunk_offset, in fs/btrfs/scrub.c:3817 [7526.387351] ------------[ cut here ]------------ [7526.387373] kernel BUG at fs/btrfs/ctree.h:3599! [7526.388001] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI [7526.388970] CPU: 2 PID: 1158150 Comm: btrfs Not tainted 5.17.0-rc8-btrfs-next-114 #4 [7526.390279] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [7526.392430] RIP: 0010:assertfail.constprop.0+0x18/0x1a [btrfs] [7526.393520] Code: f3 48 c7 c7 20 (...) [7526.396926] RSP: 0018:ffffb9154176bc40 EFLAGS: 00010246 [7526.397690] RAX: 0000000000000048 RBX: ffffa0db8a910000 RCX: 0000000000000000 [7526.398732] RDX: 0000000000000000 RSI: ffffffff9d7239a2 RDI: 00000000ffffffff [7526.399766] RBP: ffffa0db8a911e10 R08: ffffffffa71a3ca0 R09: 0000000000000001 [7526.400793] R10: 0000000000000001 R11: 0000000000000000 R12: ffffa0db4b170800 [7526.401839] R13: 00000003494b0000 R14: ffffa0db7c55b488 R15: ffffa0db8b19a000 [7526.402874] FS: 00007f6c99c40640(0000) GS:ffffa0de6d200000(0000) knlGS:0000000000000000 [7526.404038] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [7526.405040] CR2: 00007f31b0882160 CR3: 000000014b38c004 CR4: 0000000000370ee0 [7526.406112] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [7526.407148] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [7526.408169] Call Trace: [7526.408529] [7526.408839] scrub_enumerate_chunks.cold+0x11/0x79 [btrfs] [7526.409690] ? do_wait_intr_irq+0xb0/0xb0 [7526.410276] btrfs_scrub_dev+0x226/0x620 [btrfs] [7526.410995] ? preempt_count_add+0x49/0xa0 [7526.411592] btrfs_ioctl+0x1ab5/0x36d0 [btrfs] [7526.412278] ? __fget_files+0xc9/0x1b0 [7526.412825] ? kvm_sched_clock_read+0x14/0x40 [7526.413459] ? lock_release+0x155/0x4a0 [7526.414022] ? __x64_sys_ioctl+0x83/0xb0 [7526.414601] __x64_sys_ioctl+0x83/0xb0 [7526.415150] do_syscall_64+0x3b/0xc0 [7526.415675] entry_SYSCALL_64_after_hwframe+0x44/0xae [7526.416408] RIP: 0033:0x7f6c99d34397 [7526.416931] Code: 3c 1c e8 1c ff (...) [7526.419641] RSP: 002b:00007f6c99c3fca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [7526.420735] RAX: ffffffffffffffda RBX: 00005624e1e007b0 RCX: 00007f6c99d34397 [7526.421779] RDX: 00005624e1e007b0 RSI: 00000000c400941b RDI: 0000000000000003 [7526.422820] RBP: 0000000000000000 R08: 00007f6c99c40640 R09: 0000000000000000 [7526.423906] R10: 00007f6c99c40640 R11: 0000000000000246 R12: 00007fff746755de [7526.424924] R13: 00007fff746755df R14: 0000000000000000 R15: 00007f6c99c40640 [7526.425950] That assertion is relatively new, introduced with commit d04fbe19aefd2 ("btrfs: scrub: cleanup the argument list of scrub_chunk()"). The block group we get at scrub_enumerate_chunks() can actually have a start address that is smaller then the chunk offset we extracted from a device extent item we got from the commit root of the device tree. This is very rare, but it can happen due to a race with block group removal and allocation. For example, the following steps show how this can happen: 1) We are at transaction T, and we have the following blocks groups, sorted by their logical start address: [ bg A, start address A, length 1G (data) ] [ bg B, start address B, length 1G (data) ] (...) [ bg W, start address W, length 1G (data) ] --> logical address space hole of 256M, there used to be a 256M metadata block group here [ bg Y, start address Y, length 256M (metadata) ] --> Y matches W's end offset + 256M Block group Y is the block group with the highest logical address in the whole filesystem; 2) Block group Y is deleted and its extent mapping is removed by the call to remove_extent_mapping() made from btrfs_remove_block_group(). So after this point, the last element of the mapping red black tree, its rightmost node, is the mapping for block group W; 3) While still at transaction T, a new data block group is allocated, with a length of 1G. When creating the block group we do a call to find_next_chunk(), which returns the logical start address for the new block group. This calls returns X, which corresponds to the end offset of the last block group, the rightmost node in the mapping red black tree (fs_info->mapping_tree), plus one. So we get a new block group that starts at logical address X and with a length of 1G. It spans over the whole logical range of the old block group Y, that was previously removed in the same transaction. However the device extent allocated to block group X is not the same device extent that was used by block group Y, and it also does not overlap that extent, which must be always the case because we allocate extents by searching through the commit root of the device tree (otherwise it could corrupt a filesystem after a power failure or an unclean shutdown in general), so the extent allocator is behaving as expected; 4) We have a task running scrub, currently at scrub_enumerate_chunks(). There it searches for device extent items in the device tree, using its commit root. It finds a device extent item that was used by block group Y, and it extracts the value Y from that item into the local variable 'chunk_offset', using btrfs_dev_extent_chunk_offset(); It then calls btrfs_lookup_block_group() to find block group for the logical address Y - since there's currently no block group that starts at that logical address, it returns block group X, because its range contains Y. This results in triggering the assertion: ASSERT(cache->start == chunk_offset); right before calling scrub_chunk(), as cache->start is X and chunk_offset is Y. This is more likely to happen of filesystems not larger than 50G, because for these filesystems we use a 256M size for metadata block groups and a 1G size for data block groups, while for filesystems larger than 50G, we use a 1G size for both data and metadata block groups (except for zoned filesystems). It could also happen on any filesystem size due to the fact that system block groups are always smaller (32M) than both data and metadata block groups, but these are not frequently deleted, so much less likely to trigger the race. So make scrub skip any block group with a start offset that is less than the value we expect, as that means it's a new block group that was created in the current transaction. It's pointless to continue and try to scrub its extents, because scrub searches for extents using the commit root, so it won't find any. For a device replace, skip it as well for the same reasons, and we don't need to worry about the possibility of extents of the new block group not being to the new device, because we have the write duplication setup done through btrfs_map_block(). Fixes: d04fbe19aefd ("btrfs: scrub: cleanup the argument list of scrub_chunk()") CC: stable@vger.kernel.org # 5.17 Signed-off-by: Filipe Manana Signed-off-by: David Sterba