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2022-12-05btrfs: move accessor helpers into accessors.hJosef Bacik
This is a large patch, but because they're all macros it's impossible to split up. Simply copy all of the item accessors in ctree.h and paste them in accessors.h, and then update any files to include the header so everything compiles. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ reformat comments, style fixups ] Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: add a BTRFS_FS_NEED_TRANS_COMMIT flagJosef Bacik
Currently we are only using fs_info->pending_changes to indicate that we need a transaction commit. The original users for this were removed years ago and we don't have more usage in sight, so this is the only remaining reason to have this field. Add a flag so we can remove this code. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: push printk index code into their respective helpersJosef Bacik
The printk index work can be pushed into the printk helpers themselves, this allows us to further sanitize messages.h, removing the last include in the header itself. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move the printk helpers out of ctree.hJosef Bacik
We have a bunch of printk helpers that are in ctree.h. These have nothing to do with ctree.c, so move them into their own header. Subsequent patches will cleanup the printk helpers. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move assert helpers out of ctree.hJosef Bacik
These call functions that aren't defined in, or will be moved out of, ctree.h Move them to super.c where the other assert/error message code is defined. Drop the __noreturn attribute for btrfs_assertfail as objtool does not like it and fails with warnings like fs/btrfs/dir-item.o: warning: objtool: .text.unlikely: unexpected end of section fs/btrfs/xattr.o: warning: objtool: btrfs_setxattr() falls through to next function btrfs_setxattr_trans.cold() fs/btrfs/xattr.o: warning: objtool: .text.unlikely: unexpected end of section Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move fs wide helpers out of ctree.hJosef Bacik
We have several fs wide related helpers in ctree.h. The bulk of these are the incompat flag test helpers, but there are things such as btrfs_fs_closing() and the read only helpers that also aren't directly related to the ctree code. Move these into a fs.h header, which will serve as the location for file system wide related helpers. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: auto enable discard=async when possibleDavid Sterba
There's a request to automatically enable async discard for capable devices. We can do that, the async mode is designed to wait for larger freed extents and is not intrusive, with limits to iops, kbps or latency. The status and tunables will be exported in /sys/fs/btrfs/FSID/discard . The automatic selection is done if there's at least one discard capable device in the filesystem (not capable devices are skipped). Mounting with any other discard option will honor that option, notably mounting with nodiscard will keep it disabled. Link: https://lore.kernel.org/linux-btrfs/CAEg-Je_b1YtdsCR0zS5XZ_SbvJgN70ezwvRwLiCZgDGLbeMB=w@mail.gmail.com/ Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: make module init/exit match their sequenceQu Wenruo
[BACKGROUND] In theory init_btrfs_fs() and exit_btrfs_fs() should match their sequence, thus normally they should look like this: init_btrfs_fs() | exit_btrfs_fs() ----------------------+------------------------ init_A(); | init_B(); | init_C(); | | exit_C(); | exit_B(); | exit_A(); So is for the error path of init_btrfs_fs(). But it's not the case, some exit functions don't match their init functions sequence in init_btrfs_fs(). Furthermore in init_btrfs_fs(), we need to have a new error label for each new init function we added. This is not really expandable, especially recently we may add several new functions to init_btrfs_fs(). [ENHANCEMENT] The patch will introduce the following things to enhance the situation: - struct init_sequence Just a wrapper of init and exit function pointers. The init function must use int type as return value, thus some init functions need to be updated to return 0. The exit function can be NULL, as there are some init sequence just outputting a message. - struct mod_init_seq[] array This is a const array, recording all the initialization we need to do in init_btrfs_fs(), and the order follows the old init_btrfs_fs(). - bool mod_init_result[] array This is a bool array, recording if we have initialized one entry in mod_init_seq[]. The reason to split mod_init_seq[] and mod_init_result[] is to avoid section mismatch in reference. All init function are in .init.text, but if mod_init_seq[] records the @initialized member it can no longer be const, thus will be put into .data section, and cause modpost warning. For init_btrfs_fs() we just call all init functions in their order in mod_init_seq[] array, and after each call, setting corresponding mod_init_result[] to true. For exit_btrfs_fs() and error handling path of init_btrfs_fs(), we just iterate mod_init_seq[] in reverse order, and skip all uninitialized entry. With this patch, init_btrfs_fs()/exit_btrfs_fs() will be much easier to expand and will always follow the strict order. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move free space cachep's out of ctree.hJosef Bacik
This is local to the free-space-cache.c code, remove it from ctree.h and inode.c, create new init/exit functions for the cachep, and move it locally to free-space-cache.c. Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move btrfs_path_cachep out of ctree.hJosef Bacik
This is local to the ctree code, remove it from ctree.h and inode.c, create new init/exit functions for the cachep, and move it locally to ctree.c. Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move trans_handle_cachep out of ctree.hJosef Bacik
This is local to the transaction code, remove it from ctree.h and inode.c, create new helpers in the transaction to handle the init work and move the cachep locally to transaction.c. Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-10-24btrfs: make thaw time super block check to also verify checksumQu Wenruo
Previous commit a05d3c915314 ("btrfs: check superblock to ensure the fs was not modified at thaw time") only checks the content of the super block, but it doesn't really check if the on-disk super block has a matching checksum. This patch will add the checksum verification to thaw time superblock verification. This involves the following extra changes: - Export btrfs_check_super_csum() As we need to call it in super.c. - Change the argument list of btrfs_check_super_csum() Instead of passing a char *, directly pass struct btrfs_super_block * pointer. - Verify that our checksum type didn't change before checking the checksum value, like it's done at mount time Fixes: a05d3c915314 ("btrfs: check superblock to ensure the fs was not modified at thaw time") Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: relax block-group-tree feature dependency checksQu Wenruo
[BUG] When one user did a wrong attempt to clear block group tree, which can not be done through mount option, by using "-o clear_cache,space_cache=v2", it will cause the following error on a fs with block-group-tree feature: BTRFS info (device dm-1): force clearing of disk cache BTRFS info (device dm-1): using free space tree BTRFS info (device dm-1): clearing free space tree BTRFS info (device dm-1): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1) BTRFS info (device dm-1): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2) BTRFS error (device dm-1): block-group-tree feature requires fres-space-tree and no-holes BTRFS error (device dm-1): super block corruption detected before writing it to disk BTRFS: error (device dm-1) in write_all_supers:4318: errno=-117 Filesystem corrupted (unexpected superblock corruption detected) BTRFS warning (device dm-1: state E): Skipping commit of aborted transaction. [CAUSE] Although the dependency for block-group-tree feature is just an artificial one (to reduce test matrix), we put the dependency check into btrfs_validate_super(). This is too strict, and during space cache clearing, we will have a window where free space tree is cleared, and we need to commit the super block. In that window, we had block group tree without v2 cache, and triggered the artificial dependency check. This is not necessary at all, especially for such a soft dependency. [FIX] Introduce a new helper, btrfs_check_features(), to do all the runtime limitation checks, including: - Unsupported incompat flags check - Unsupported compat RO flags check - Setting missing incompat flags - Artificial feature dependency checks Currently only block group tree will rely on this. - Subpage runtime check for v1 cache With this helper, we can move quite some checks from open_ctree()/btrfs_remount() into it, and just call it after btrfs_parse_options(). Now "-o clear_cache,space_cache=v2" will not trigger the above error anymore. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ edit messages ] Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: separate out the extent state and extent buffer init codeJosef Bacik
In order to help separate the extent buffer from the extent io tree code we need to break up the init functions. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: enhance unsupported compat RO flags handlingQu Wenruo
Currently there are two corner cases not handling compat RO flags correctly: - Remount We can still mount the fs RO with compat RO flags, then remount it RW. We should not allow any write into a fs with unsupported RO flags. - Still try to search block group items In fact, behavior/on-disk format change to extent tree should not need a full incompat flag. And since we can ensure fs with unsupported RO flags never got any writes (with above case fixed), then we can even skip block group items search at mount time. This patch will enhance the unsupported RO compat flags by: - Reject read-write remount if there are unsupported RO compat flags - Go dummy block group items directly for unsupported RO compat flags In fact, only changes to chunk/subvolume/root/csum trees should go incompat flags. The latter part should allow future change to extent tree to be compat RO flags. Thus this patch also needs to be backported to all stable trees. CC: stable@vger.kernel.org # 4.9+ Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: dump all space infos if we abort transaction due to ENOSPCQu Wenruo
We have hit some transaction abort due to -ENOSPC internally. Normally we should always reserve enough space for metadata for every transaction, thus hitting -ENOSPC should really indicate some cases we didn't expect. But unfortunately current error reporting will only give a kernel warning and stack trace, not really helpful to debug what's causing the problem. And mount option debug_enospc can only help when user can reproduce the problem, but under most cases, such transaction abort by -ENOSPC is really hard to reproduce. So this patch will dump all space infos (data, metadata, system) when we abort the first transaction with -ENOSPC. This should at least provide some clue to us. The example of a dump would look like this: BTRFS: Transaction aborted (error -28) WARNING: CPU: 8 PID: 3366 at fs/btrfs/transaction.c:2137 btrfs_commit_transaction+0xf81/0xfb0 [btrfs] <call trace skipped> ---[ end trace 0000000000000000 ]--- BTRFS info (device dm-1: state A): dumping space info: BTRFS info (device dm-1: state A): space_info DATA has 6791168 free, is not full BTRFS info (device dm-1: state A): space_info total=8388608, used=1597440, pinned=0, reserved=0, may_use=0, readonly=0 zone_unusable=0 BTRFS info (device dm-1: state A): space_info METADATA has 257114112 free, is not full BTRFS info (device dm-1: state A): space_info total=268435456, used=131072, pinned=180224, reserved=65536, may_use=10878976, readonly=65536 zone_unusable=0 BTRFS info (device dm-1: state A): space_info SYSTEM has 8372224 free, is not full BTRFS info (device dm-1: state A): space_info total=8388608, used=16384, pinned=0, reserved=0, may_use=0, readonly=0 zone_unusable=0 BTRFS info (device dm-1: state A): global_block_rsv: size 3670016 reserved 3670016 BTRFS info (device dm-1: state A): trans_block_rsv: size 0 reserved 0 BTRFS info (device dm-1: state A): chunk_block_rsv: size 0 reserved 0 BTRFS info (device dm-1: state A): delayed_block_rsv: size 4063232 reserved 4063232 BTRFS info (device dm-1: state A): delayed_refs_rsv: size 3145728 reserved 3145728 BTRFS: error (device dm-1: state A) in btrfs_commit_transaction:2137: errno=-28 No space left BTRFS info (device dm-1: state EA): forced readonly Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: check superblock to ensure the fs was not modified at thaw timeQu Wenruo
[BACKGROUND] There is an incident report that, one user hibernated the system, with one btrfs on removable device still mounted. Then by some incident, the btrfs got mounted and modified by another system/OS, then back to the hibernated system. After resuming from the hibernation, new write happened into the victim btrfs. Now the fs is completely broken, since the underlying btrfs is no longer the same one before the hibernation, and the user lost their data due to various transid mismatch. [REPRODUCER] We can emulate the situation using the following small script: truncate -s 1G $dev mkfs.btrfs -f $dev mount $dev $mnt fsstress -w -d $mnt -n 500 sync xfs_freeze -f $mnt cp $dev $dev.backup # There is no way to mount the same cloned fs on the same system, # as the conflicting fsid will be rejected by btrfs. # Thus here we have to wipe the fs using a different btrfs. mkfs.btrfs -f $dev.backup dd if=$dev.backup of=$dev bs=1M xfs_freeze -u $mnt fsstress -w -d $mnt -n 20 umount $mnt btrfs check $dev The final fsck will fail due to some tree blocks has incorrect fsid. This is enough to emulate the problem hit by the unfortunate user. [ENHANCEMENT] Although such case should not be that common, it can still happen from time to time. From the view of btrfs, we can detect any unexpected super block change, and if there is any unexpected change, we just mark the fs read-only, and thaw the fs. By this we can limit the damage to minimal, and I hope no one would lose their data by this anymore. Suggested-by: Goffredo Baroncelli <kreijack@libero.it> Link: https://lore.kernel.org/linux-btrfs/83bf3b4b-7f4c-387a-b286-9251e3991e34@bluemole.com/ Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: move btrfs_bio allocation to volumes.cChristoph Hellwig
volumes.c is the place that implements the storage layer using the btrfs_bio structure, so move the bio_set and allocation helpers there as well. To make up for the new initialization boilerplate, merge the two init/exit helpers in extent_io.c into a single one. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Tested-by: Nikolay Borisov <nborisov@suse.com> Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26btrfs: don't print information about space cache or tree every remountMaciej S. Szmigiero
btrfs currently prints information about space cache or free space tree being in use on every remount, regardless whether such remount actually enabled or disabled one of these features. This is actually unnecessary since providing remount options changing the state of these features will explicitly print the appropriate notice. Let's instead print such unconditional information just on an initial mount to avoid filling the kernel log when, for example, laptop-mode-tools remount the fs on some events. Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-08-05Merge tag 'mm-stable-2022-08-03' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: "Most of the MM queue. A few things are still pending. Liam's maple tree rework didn't make it. This has resulted in a few other minor patch series being held over for next time. Multi-gen LRU still isn't merged as we were waiting for mapletree to stabilize. The current plan is to merge MGLRU into -mm soon and to later reintroduce mapletree, with a view to hopefully getting both into 6.1-rc1. Summary: - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe Lin, Yang Shi, Anshuman Khandual and Mike Rapoport - Some kmemleak fixes from Patrick Wang and Waiman Long - DAMON updates from SeongJae Park - memcg debug/visibility work from Roman Gushchin - vmalloc speedup from Uladzislau Rezki - more folio conversion work from Matthew Wilcox - enhancements for coherent device memory mapping from Alex Sierra - addition of shared pages tracking and CoW support for fsdax, from Shiyang Ruan - hugetlb optimizations from Mike Kravetz - Mel Gorman has contributed some pagealloc changes to improve latency and realtime behaviour. - mprotect soft-dirty checking has been improved by Peter Xu - Many other singleton patches all over the place" [ XFS merge from hell as per Darrick Wong in https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ] * tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits) tools/testing/selftests/vm/hmm-tests.c: fix build mm: Kconfig: fix typo mm: memory-failure: convert to pr_fmt() mm: use is_zone_movable_page() helper hugetlbfs: fix inaccurate comment in hugetlbfs_statfs() hugetlbfs: cleanup some comments in inode.c hugetlbfs: remove unneeded header file hugetlbfs: remove unneeded hugetlbfs_ops forward declaration hugetlbfs: use helper macro SZ_1{K,M} mm: cleanup is_highmem() mm/hmm: add a test for cross device private faults selftests: add soft-dirty into run_vmtests.sh selftests: soft-dirty: add test for mprotect mm/mprotect: fix soft-dirty check in can_change_pte_writable() mm: memcontrol: fix potential oom_lock recursion deadlock mm/gup.c: fix formatting in check_and_migrate_movable_page() xfs: fail dax mount if reflink is enabled on a partition mm/memcontrol.c: remove the redundant updating of stats_flush_threshold userfaultfd: don't fail on unrecognized features hugetlb_cgroup: fix wrong hugetlb cgroup numa stat ...
2022-07-25btrfs: use mask for all RAID1* profiles in btrfs_calc_avail_data_spaceDavid Sterba
There's a sequence of hard coded values for RAID1 profiles that are already stored in the raid_attr table that should be used instead. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-07-25btrfs: use named constant for reserved device spaceQu Wenruo
There's a reserved space on each device of size 1MiB that can be used by bootloaders or to avoid accidental overwrite. Use a symbolic constant with the explaining comment instead of hard coding the value and multiple comments. Note: since btrfs-progs v4.1, mkfs.btrfs will reserve the first 1MiB for the primary super block (at offset 64KiB), until then the range could have been used by mistake. Kernel has been always respecting the 1MiB range for writes. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
2022-07-25btrfs: remove btrfs_end_io_wqChristoph Hellwig
All reads bio that go through btrfs_map_bio need to be completed in user context. And read I/Os are the most common and timing critical in almost any file system workloads. Embed a work_struct into struct btrfs_bio and use it to complete all read bios submitted through btrfs_map, using the REQ_META flag to decide which workqueue they are placed on. This removes the need for a separate 128 byte allocation (typically rounded up to 192 bytes by slab) for all reads with a size increase of 24 bytes for struct btrfs_bio. Future patches will reorganize struct btrfs_bio to make use of this extra space for writes as well. (All sizes are based a on typical 64-bit non-debug build) Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Sterba <dsterba@suse.com>
2022-07-25btrfs: don't use btrfs_bio_wq_end_io for compressed writesChristoph Hellwig
Compressed write bio completion is the only user of btrfs_bio_wq_end_io for writes, and the use of btrfs_bio_wq_end_io is a little suboptimal here as we only real need user context for the final completion of a compressed_bio structure, and not every single bio completion. Add a work_struct to struct compressed_bio instead and use that to call finish_compressed_bio_write. This allows to remove all handling of write bios in the btrfs_bio_wq_end_io infrastructure. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Sterba <dsterba@suse.com>
2022-07-25btrfs: add trace event for submitted RAID56 bioQu Wenruo
Add tracepoint for better insight to how the RAID56 data are submitted. The output looks like this: (trace event header and UUID skipped) raid56_read_partial: full_stripe=389152768 devid=3 type=DATA1 offset=32768 opf=0x0 physical=323059712 len=32768 raid56_read_partial: full_stripe=389152768 devid=1 type=DATA2 offset=0 opf=0x0 physical=67174400 len=65536 raid56_write_stripe: full_stripe=389152768 devid=3 type=DATA1 offset=0 opf=0x1 physical=323026944 len=32768 raid56_write_stripe: full_stripe=389152768 devid=2 type=PQ1 offset=0 opf=0x1 physical=323026944 len=32768 The above debug output is from a 32K data write into an empty RAID56 data chunk. Some explanation on the event output: full_stripe: the logical bytenr of the full stripe devid: btrfs devid type: raid stripe type. DATA1: the first data stripe DATA2: the second data stripe PQ1: the P stripe PQ2: the Q stripe offset: the offset inside the stripe. opf: the bio op type physical: the physical offset the bio is for len: the length of the bio The first two lines are from partial RMW read, which is reading the remaining data stripes from disks. The last two lines are for full stripe RMW write, which is writing the involved two 16K stripes (one for DATA1 stripe, one for P stripe). The stripe for DATA2 doesn't need to be written. There are 5 types of trace events: - raid56_read_partial Read remaining data for regular read/write path. - raid56_write_stripe Write the modified stripes for regular read/write path. - raid56_scrub_read_recover Read remaining data for scrub recovery path. - raid56_scrub_write_stripe Write the modified stripes for scrub path. - raid56_scrub_read Read remaining data for scrub path. Also, since the trace events are included at super.c, we have to export needed structure definitions to 'raid56.h' and include the header in super.c, or we're unable to access those members. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ reformat comments ] Signed-off-by: David Sterba <dsterba@suse.com>
2022-07-25btrfs: fix typos in commentsDavid Sterba
Codespell has found a few typos. Signed-off-by: David Sterba <dsterba@suse.com>
2022-07-03mm: shrinkers: provide shrinkers with namesRoman Gushchin
Currently shrinkers are anonymous objects. For debugging purposes they can be identified by count/scan function names, but it's not always useful: e.g. for superblock's shrinkers it's nice to have at least an idea of to which superblock the shrinker belongs. This commit adds names to shrinkers. register_shrinker() and prealloc_shrinker() functions are extended to take a format and arguments to master a name. In some cases it's not possible to determine a good name at the time when a shrinker is allocated. For such cases shrinker_debugfs_rename() is provided. The expected format is: <subsystem>-<shrinker_type>[:<instance>]-<id> For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair. After this change the shrinker debugfs directory looks like: $ cd /sys/kernel/debug/shrinker/ $ ls dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42 mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43 mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44 rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49 sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13 sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36 sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19 sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10 sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9 sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37 sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38 sb-dax-11 sb-proc-45 sb-tmpfs-35 sb-debugfs-7 sb-proc-46 sb-tmpfs-40 [roman.gushchin@linux.dev: fix build warnings] Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle Reported-by: kernel test robot <lkp@intel.com> Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Dave Chinner <dchinner@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-07btrfs: add error messages to all unrecognized mount optionsDavid Sterba
Almost none of the errors stemming from a valid mount option but wrong value prints a descriptive message which would help to identify why mount failed. Like in the linked report: $ uname -r v4.19 $ mount -o compress=zstd /dev/sdb /mnt mount: /mnt: wrong fs type, bad option, bad superblock on /dev/sdb, missing codepage or helper program, or other error. $ dmesg ... BTRFS error (device sdb): open_ctree failed Errors caused by memory allocation failures are left out as it's not a user error so reporting that would be confusing. Link: https://lore.kernel.org/linux-btrfs/9c3fec36-fc61-3a33-4977-a7e207c3fa4e@gmx.de/ CC: stable@vger.kernel.org # 4.9+ Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-06-06btrfs: prevent remounting to v1 space cache for subpage mountQu Wenruo
Upstream commit 9f73f1aef98b ("btrfs: force v2 space cache usage for subpage mount") forces subpage mount to use v2 cache, to avoid deprecated v1 cache which doesn't support subpage properly. But there is a loophole that user can still remount to v1 cache. The existing check will only give users a warning, but does not really prevent to do the remount. Although remounting to v1 will not cause any problems since the v1 cache will always be marked invalid when mounted with a different page size, it's still better to prevent v1 cache at all for subpage mounts. Fixes: 9f73f1aef98b ("btrfs: force v2 space cache usage for subpage mount") CC: stable@vger.kernel.org # 5.15+ Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-16btrfs: use normal workqueues for scrubChristoph Hellwig
All three scrub workqueues don't need ordered execution or thread disabling threshold (as the thresh parameter is less than DFT_THRESHOLD). Just switch to the normal workqueues that use a lot less resources, especially in the work_struct vs btrfs_work structures. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-16btrfs: simplify WQ_HIGHPRI handling in struct btrfs_workqueueChristoph Hellwig
Just let the one caller that wants optional WQ_HIGHPRI handling allocate a separate btrfs_workqueue for that. This allows to rename struct __btrfs_workqueue to btrfs_workqueue, remove a pointer indirection and separate allocation for all btrfs_workqueue users and generally simplify the code. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-16btrfs: add messages to printk indexJonathan Lassoff
In order for end users to quickly react to new issues that come up in production, it is proving useful to leverage this printk indexing system. This printk index enables kernel developers to use calls to printk() with changeable ad-hoc format strings, while still enabling end users to detect changes and develop a semi-stable interface for detecting and parsing these messages. So that detailed Btrfs messages are captured by this printk index, this patch wraps btrfs_printk and btrfs_handle_fs_error with macros. Example of the generated list: https://lore.kernel.org/lkml/12588e13d51a9c3bf59467d3fc1ac2162f1275c1.1647539056.git.jof@thejof.com Signed-off-by: Jonathan Lassoff <jof@thejof.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-03-14btrfs: add filesystems state details to error messagesSweet Tea Dorminy
When a filesystem goes read-only due to an error, multiple errors tend to be reported, some of which are knock-on failures. Logging fs_states, in btrfs_handle_fs_error() and btrfs_printk() helps distinguish the first error from subsequent messages which may only exist due to an error state. Under the new format, most initial errors will look like: `BTRFS: error (device loop0) in ...` while subsequent errors will begin with: `error (device loop0: state E) in ...` An initial transaction abort error will look like `error (device loop0: state A) in ...` and subsequent messages will contain `(device loop0: state EA) in ...` In addition to the error states we can also print other states that are temporary, like remounting, device replace, or indicate a global state that may affect functionality. Now implemented: E - filesystem error detected A - transaction aborted L - log tree errors M - remounting in progress R - device replace in progress C - data checksums not verified (mounted with ignoredatacsums) Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-03-14btrfs: disable space cache related mount options for extent tree v2Josef Bacik
We cannot fall back on the slow caching for extent tree v2, which means we can't just arbitrarily clear the free space trees at mount time. Furthermore we can't do v1 space cache with extent tree v2. Simply ignore these mount options for extent tree v2 as they aren't relevant. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-03-14btrfs: match stale devices by dev_tAnand Jain
After the commit "btrfs: harden identification of the stale device", we don't have to match the device path anymore. Instead, we match the dev_t. So pass in the dev_t instead of the device path, in the call chain btrfs_forget_devices()->btrfs_free_stale_devices(). Signed-off-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-22mm: remove cleancacheChristoph Hellwig
Patch series "remove Xen tmem leftovers". Since the removal of the Xen tmem driver in 2019, the cleancache hooks are entirely unused, as are large parts of frontswap. This series against linux-next (with the folio changes included) removes cleancaches, and cuts down frontswap to the bits actually used by zswap. This patch (of 13): The cleancache subsystem is unused since the removal of Xen tmem driver in commit 814bbf49dcd0 ("xen: remove tmem driver"). [akpm@linux-foundation.org: remove now-unreachable code] Link: https://lkml.kernel.org/r/20211224062246.1258487-1-hch@lst.de Link: https://lkml.kernel.org/r/20211224062246.1258487-2-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Juergen Gross <jgross@suse.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Vitaly Wool <vitaly.wool@konsulko.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-07btrfs: remove reada infrastructureQu Wenruo
Currently there is only one user for btrfs metadata readahead, and that's scrub. But even for the single user, it's not providing the correct functionality it needs, as scrub needs reada for commit root, which current readahead can't provide. (Although it's pretty easy to add such feature). Despite this, there are some extra problems related to metadata readahead: - Duplicated feature with btrfs_path::reada - Partly duplicated feature of btrfs_fs_info::buffer_radix Btrfs already caches its metadata in buffer_radix, while readahead tries to read the tree block no matter if it's already cached. - Poor layer separation Metadata readahead works kinda at device level. This is definitely not the correct layer it should be, since metadata is at btrfs logical address space, it should not bother device at all. This brings extra chance for bugs to sneak in, while brings unnecessary complexity. - Dead code In the very beginning of scrub.c we have #undef DEBUG, rendering all the debug related code useless and unable to test. Thus here I purpose to remove the metadata readahead mechanism completely. [BENCHMARK] There is a full benchmark for the scrub performance difference using the old btrfs_reada_add() and btrfs_path::reada. For the worst case (no dirty metadata, slow HDD), there could be a 5% performance drop for scrub. For other cases (even SATA SSD), there is no distinguishable performance difference. The number is reported scrub speed, in MiB/s. The resolution is limited by the reported duration, which only has a resolution of 1 second. Old New Diff SSD 455.3 466.332 +2.42% HDD 103.927 98.012 -5.69% Comprehensive test methodology is in the cover letter of the patch. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-10-26btrfs: add a BTRFS_FS_ERROR helperJosef Bacik
We have a few flags that are inconsistently used to describe the fs in different states of failure. As of 5963ffcaf383 ("btrfs: always abort the transaction if we abort a trans handle") we will always set BTRFS_FS_STATE_ERROR if we abort, so we don't have to check both ABORTED and ERROR to see if things have gone wrong. Add a helper to check BTRFS_FS_STATE_ERROR and then convert all checkers of FS_STATE_ERROR to use the helper. The TRANS_ABORTED bit check was added in af7227338135 ("Btrfs: clean up resources during umount after trans is aborted") but is not actually specific. Reviewed-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-10-26btrfs: use latest_dev in btrfs_show_devnameAnand Jain
The test case btrfs/238 reports the warning below: WARNING: CPU: 3 PID: 481 at fs/btrfs/super.c:2509 btrfs_show_devname+0x104/0x1e8 [btrfs] CPU: 2 PID: 1 Comm: systemd Tainted: G W O 5.14.0-rc1-custom #72 Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 Call trace: btrfs_show_devname+0x108/0x1b4 [btrfs] show_mountinfo+0x234/0x2c4 m_show+0x28/0x34 seq_read_iter+0x12c/0x3c4 vfs_read+0x29c/0x2c8 ksys_read+0x80/0xec __arm64_sys_read+0x28/0x34 invoke_syscall+0x50/0xf8 do_el0_svc+0x88/0x138 el0_svc+0x2c/0x8c el0t_64_sync_handler+0x84/0xe4 el0t_64_sync+0x198/0x19c Reason: While btrfs_prepare_sprout() moves the fs_devices::devices into fs_devices::seed_list, the btrfs_show_devname() searches for the devices and found none, leading to the warning as in above. Fix: latest_dev is updated according to the changes to the device list. That means we could use the latest_dev->name to show the device name in /proc/self/mounts, the pointer will be always valid as it's assigned before the device is deleted from the list in remove or replace. The RCU protection is sufficient as the device structure is freed after synchronization. Reported-by: Su Yue <l@damenly.su> Tested-by: Su Yue <l@damenly.su> Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-10-26btrfs: convert latest_bdev type to btrfs_device and renameAnand Jain
In preparation to fix a bug in btrfs_show_devname(). Convert fs_devices::latest_bdev type from struct block_device to struct btrfs_device and, rename the member to fs_devices::latest_dev. So that btrfs_show_devname() can use fs_devices::latest_dev::name. Tested-by: Su Yue <l@damenly.su> Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-08-23btrfs: allow idmapped mountChristian Brauner
Now that we converted btrfs internally to account for idmapped mounts allow the creation of idmapped mounts on by setting the FS_ALLOW_IDMAP flag. We only need to raise this flag on the btrfs_root_fs_type filesystem since btrfs_mount_root() is ultimately responsible for allocating the superblock and is called into from btrfs_mount() associated with btrfs_fs_type. The conversion of the btrfs inode operations was straightforward. Regarding btrfs specific ioctls that perform checks based on inode permissions only those have been allowed that are not filesystem wide operations and hence can be reasonably charged against a specific mount. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-08-23btrfs: introduce btrfs_search_backwards functionMarcos Paulo de Souza
It's a common practice to start a search using offset (u64)-1, which is the u64 maximum value, meaning that we want the search_slot function to be set in the last item with the same objectid and type. Once we are in this position, it's a matter to start a search backwards by calling btrfs_previous_item, which will check if we'll need to go to a previous leaf and other necessary checks, only to be sure that we are in last offset of the same object and type. The new btrfs_search_backwards function does the all these steps when necessary, and can be used to avoid code duplication. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-08-23btrfs: print if fsverity support is built in when loading moduleDavid Sterba
As fsverity support depends on a config option, print that at module load time like we do for similar features. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-08-23btrfs: initial fsverity supportBoris Burkov
Add support for fsverity in btrfs. To support the generic interface in fs/verity, we add two new item types in the fs tree for inodes with verity enabled. One stores the per-file verity descriptor and btrfs verity item and the other stores the Merkle tree data itself. Verity checking is done in end_page_read just before a page is marked uptodate. This naturally handles a variety of edge cases like holes, preallocated extents, and inline extents. Some care needs to be taken to not try to verity pages past the end of the file, which are accessed by the generic buffered file reading code under some circumstances like reading to the end of the last page and trying to read again. Direct IO on a verity file falls back to buffered reads. Verity relies on PageChecked for the Merkle tree data itself to avoid re-walking up shared paths in the tree. For this reason, we need to cache the Merkle tree data. Since the file is immutable after verity is turned on, we can cache it at an index past EOF. Use the new inode ro_flags to store verity on the inode item, so that we can enable verity on a file, then rollback to an older kernel and still mount the file system and read the file. Since we can't safely write the file anymore without ruining the invariants of the Merkle tree, we mark a ro_compat flag on the file system when a file has verity enabled. Acked-by: Eric Biggers <ebiggers@google.com> Co-developed-by: Chris Mason <clm@fb.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-08-23btrfs: allow read-write for 4K sectorsize on 64K page size systemsQu Wenruo
Since now we support data and metadata read-write for subpage, remove the RO requirement for subpage mount. There are some extra limitations though: - For now, subpage RW mount is still considered experimental Thus that mount warning will still be there. - No compression support There are still quite some PAGE_SIZE hard coded and quite some call sites use extent_clear_unlock_delalloc() to unlock locked_page. This will screw up subpage helpers. Now for subpage RW mount, no matter what mount option or inode attr is set, all writes will not be compressed. Although reading compressed data has no problem. - No defrag for subpage case The defrag support for subpage case will come in later patches, which will also rework the defrag workflow. - No inline extent will be created This is mostly due to the fact that filemap_fdatawrite_range() will trigger more write than the range specified. In fallocate calls, this behavior can make us to writeback which can be inlined, before we enlarge the i_size. This is a very special corner case, and even current btrfs check won't report error on such inline extent + regular extent. But considering how much effort has been put to prevent such inline + regular, I'd prefer to cut off inline extent completely until we have a good solution. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-08-23btrfs: constify and cleanup variables in comparatorsDavid Sterba
Comparators just read the data and thus get const parameters. This should be also preserved by the local variables, update all comparators passed to sort or bsearch. Cleanups: - unnecessary casts are dropped - btrfs_cmp_device_free_bytes is cleaned up to follow the common pattern and 'inline' is dropped as the function address is taken Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-22btrfs: shorten integrity checker extent data mount optionDavid Sterba
Subjectively, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA is quite long and calling it CHECK_INTEGRITY_DATA still keeps the meaning and matches the mount option name. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-21btrfs: always abort the transaction if we abort a trans handleJosef Bacik
While stress testing our error handling I noticed that sometimes we would still commit the transaction even though we had aborted the transaction. Currently we track if a trans handle has dirtied any metadata, and if it hasn't we mark the filesystem as having an error (so no new transactions can be started), but we will allow the current transaction to complete as we do not mark the transaction itself as having been aborted. This sounds good in theory, but we were not properly tracking IO errors in btrfs_finish_ordered_io, and thus committing the transaction with bogus free space data. This isn't necessarily a problem per-se with the free space cache, as the other guards in place would have kept us from accepting the free space cache as valid, but highlights a real world case where we had a bug and could have corrupted the filesystem because of it. This "skip abort on empty trans handle" is nice in theory, but assumes we have perfect error handling everywhere, which we clearly do not. Also we do not allow further transactions to be started, so all this does is save the last transaction that was happening, which doesn't necessarily gain us anything other than the potential for real corruption. Remove this particular bit of code, if we decide we need to abort the transaction then abort the current one and keep us from doing real harm to the file system, regardless of whether this specific trans handle dirtied anything or not. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-20btrfs: more graceful errors/warnings on 32bit systems when reaching limitsQu Wenruo
Btrfs uses internally mapped u64 address space for all its metadata. Due to the page cache limit on 32bit systems, btrfs can't access metadata at or beyond (ULONG_MAX + 1) << PAGE_SHIFT. See how MAX_LFS_FILESIZE and page::index are defined. This is 16T for 4K page size while 256T for 64K page size. Users can have a filesystem which doesn't have metadata beyond the boundary at mount time, but later balance can cause it to create metadata beyond the boundary. And modification to MM layer is unrealistic just for such minor use case. We can't do more than to prevent mounting such filesystem or warn early when the numbers are still within the limits. To address such problem, this patch will introduce the following checks: - Mount time rejection This will reject any fs which has metadata chunk at or beyond the boundary. - Mount time early warning If there is any metadata chunk beyond 5/8th of the boundary, we do an early warning and hope the end user will see it. - Runtime extent buffer rejection If we're going to allocate an extent buffer at or beyond the boundary, reject such request with EOVERFLOW. This is definitely going to cause problems like transaction abort, but we have no better ways. - Runtime extent buffer early warning If an extent buffer beyond 5/8th of the max file size is allocated, do an early warning. Above error/warning message will only be printed once for each fs to reduce dmesg flood. If the mount is rejected, the filesystem will be mountable only on a 64bit host. Link: https://lore.kernel.org/linux-btrfs/1783f16d-7a28-80e6-4c32-fdf19b705ed0@gmx.com/ Reported-by: Erik Jensen <erikjensen@rkjnsn.net> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-03-02btrfs: fix spurious free_space_tree remount warningBoris Burkov
The intended logic of the check is to catch cases where the desired free_space_tree setting doesn't match the mounted setting, and the remount is anything but ro->rw. However, it makes the mistake of checking equality on a masked integer (btrfs_test_opt) against a boolean (btrfs_fs_compat_ro). If you run the reproducer: $ mount -o space_cache=v2 dev mnt $ mount -o remount,ro mnt you would expect no warning, because the remount is not attempting to change the free space tree setting, but we do see the warning. To fix this, add explicit bool type casts to the condition. I tested a variety of transitions: sudo mount -o space_cache=v2 /dev/vg0/lv0 mnt/lol (fst enabled) mount -o remount,ro mnt/lol (no warning, no fst change) sudo mount -o remount,rw,space_cache=v1,clear_cache (no warning, ro->rw) sudo mount -o remount,rw,space_cache=v2 mnt (warning, rw->rw with change) sudo mount -o remount,ro mnt (no warning, no fst change) sudo mount -o remount,rw,space_cache=v2 mnt (no warning, no fst change) Reported-by: Chris Murphy <lists@colorremedies.com> CC: stable@vger.kernel.org # 5.11 Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>