- 03 Oct, 2023 4 commits
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Filipe Manana authored
At btrfs_cow_block() we have these checks to verify we are not using a stale transaction (a past transaction with an unblocked state or higher), and the only thing we do is to trigger a WARN with a message and a stack trace. This however is a critical problem, highly unexpected and if it happens it's most likely due to a bug, so we should error out and turn the fs into error state so that such issue is much more easily noticed if it's triggered. The problem is critical because using such stale transaction will lead to not persisting the extent buffer used for the COW operation, as allocating a tree block adds the range of the respective extent buffer to the ->dirty_pages iotree of the transaction, and a stale transaction, in the unlocked state or higher, will not flush dirty extent buffers anymore, therefore resulting in not persisting the tree block and resource leaks (not cleaning the dirty_pages iotree for example). So do the following changes: 1) Return -EUCLEAN if we find a stale transaction; 2) Turn the fs into error state, with error -EUCLEAN, so that no transaction can be committed, and generate a stack trace; 3) Combine both conditions into a single if statement, as both are related and have the same error message; 4) Mark the check as unlikely, since this is not expected to ever happen. Signed-off-by:
Filipe Manana <fdmanana@suse.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
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Filipe Manana authored
Commit b7af0635 ("btrfs: print transaction aborted messages with an error level") changed the log level of transaction aborted messages from a debug level to an error level, so that such messages are always visible even on production systems where the log level is normally above the debug level (and also on some syzbot reports). Later, commit fccf0c84 ("btrfs: move btrfs_abort_transaction to transaction.c") changed the log level back to debug level when the error number for a transaction abort should not have a stack trace printed. This happened for absolutely no reason. It's always useful to print transaction abort messages with an error level, regardless of whether the error number should cause a stack trace or not. So change back the log level to error level. Fixes: fccf0c84 ("btrfs: move btrfs_abort_transaction to transaction.c") CC: stable@vger.kernel.org # 6.5+ Reviewed-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Qu Wenruo authored
[BUG] The following script would allow invalid mount options to be specified (although such invalid options would just be ignored): # mkfs.btrfs -f $dev # mount $dev $mnt1 <<< Successful mount expected # mount $dev $mnt2 -o junk <<< Failed mount expected # echo $? 0 [CAUSE] For the 2nd mount, since the fs is already mounted, we won't go through open_ctree() thus no btrfs_parse_options(), but only through btrfs_parse_subvol_options(). However we do not treat unrecognized options from valid but irrelevant options, thus those invalid options would just be ignored by btrfs_parse_subvol_options(). [FIX] Add the handling for Opt_err to handle invalid options and error out, while still ignore other valid options inside btrfs_parse_subvol_options(). Reported-by:
Anand Jain <anand.jain@oracle.com> CC: stable@vger.kernel.org # 4.14+ Signed-off-by:
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Josef Bacik authored
Jens reported the following warnings from -Wmaybe-uninitialized recent Linus' branch. In file included from ./include/asm-generic/rwonce.h:26, from ./arch/arm64/include/asm/rwonce.h:71, from ./include/linux/compiler.h:246, from ./include/linux/export.h:5, from ./include/linux/linkage.h:7, from ./include/linux/kernel.h:17, from fs/btrfs/ioctl.c:6: In function ‘instrument_copy_from_user_before’, inlined from ‘_copy_from_user’ at ./include/linux/uaccess.h:148:3, inlined from ‘copy_from_user’ at ./include/linux/uaccess.h:183:7, inlined from ‘btrfs_ioctl_space_info’ at fs/btrfs/ioctl.c:2999:6, inlined from ‘btrfs_ioctl’ at fs/btrfs/ioctl.c:4616:10: ./include/linux/kasan-checks.h:38:27: warning: ‘space_args’ may be used uninitialized [-Wmaybe-uninitialized] 38 | #define kasan_check_write __kasan_check_write ./include/linux/instrumented.h:129:9: note: in expansion of macro ‘kasan_check_write’ 129 | kasan_check_write(to, n); | ^~~~~~~~~~~~~~~~~ ./include/linux/kasan-checks.h: In function ‘btrfs_ioctl’: ./include/linux/kasan-checks.h:20:6: note: by argument 1 of type ‘const volatile void *’ to ‘__kasan_check_write’ declared here 20 | bool __kasan_check_write(const volatile void *p, unsigned int size); | ^~~~~~~~~~~~~~~~~~~ fs/btrfs/ioctl.c:2981:39: note: ‘space_args’ declared here 2981 | struct btrfs_ioctl_space_args space_args; | ^~~~~~~~~~ In function ‘instrument_copy_from_user_before’, inlined from ‘_copy_from_user’ at ./include/linux/uaccess.h:148:3, inlined from ‘copy_from_user’ at ./include/linux/uaccess.h:183:7, inlined from ‘_btrfs_ioctl_send’ at fs/btrfs/ioctl.c:4343:9, inlined from ‘btrfs_ioctl’ at fs/btrfs/ioctl.c:4658:10: ./include/linux/kasan-checks.h:38:27: warning: ‘args32’ may be used uninitialized [-Wmaybe-uninitialized] 38 | #define kasan_check_write __kasan_check_write ./include/linux/instrumented.h:129:9: note: in expansion of macro ‘kasan_check_write’ 129 | kasan_check_write(to, n); | ^~~~~~~~~~~~~~~~~ ./include/linux/kasan-checks.h: In function ‘btrfs_ioctl’: ./include/linux/kasan-checks.h:20:6: note: by argument 1 of type ‘const volatile void *’ to ‘__kasan_check_write’ declared here 20 | bool __kasan_check_write(const volatile void *p, unsigned int size); | ^~~~~~~~~~~~~~~~~~~ fs/btrfs/ioctl.c:4341:49: note: ‘args32’ declared here 4341 | struct btrfs_ioctl_send_args_32 args32; | ^~~~~~ This was due to his config options and having KASAN turned on, which adds some extra checks around copy_from_user(), which then triggered the -Wmaybe-uninitialized checker for these cases. Fix the warnings by initializing the different structs we're copying into. Reported-by:Jens Axboe <axboe@kernel.dk> Signed-off-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
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- 21 Sep, 2023 2 commits
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Josef Bacik authored
Jens reported a compiler warning when using CONFIG_CC_OPTIMIZE_FOR_SIZE=y that looks like this fs/btrfs/tree-log.c: In function ‘btrfs_log_prealloc_extents’: fs/btrfs/tree-log.c:4828:23: warning: ‘start_slot’ may be used uninitialized [-Wmaybe-uninitialized] 4828 | ret = copy_items(trans, inode, dst_path, path, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 4829 | start_slot, ins_nr, 1, 0); | ~~~~~~~~~~~~~~~~~~~~~~~~~ fs/btrfs/tree-log.c:4725:13: note: ‘start_slot’ was declared here 4725 | int start_slot; | ^~~~~~~~~~ The compiler is incorrect, as we only use this code when ins_len > 0, and when ins_len > 0 we have start_slot properly initialized. However we generally find the -Wmaybe-uninitialized warnings valuable, so initialize start_slot to get rid of the warning. Reported-by:
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Josef Bacik authored
Jens reported a compiler error when using CONFIG_CC_OPTIMIZE_FOR_SIZE=y that looks like this In function ‘gather_device_info’, inlined from ‘btrfs_create_chunk’ at fs/btrfs/volumes.c:5507:8: fs/btrfs/volumes.c:5245:48: warning: ‘dev_offset’ may be used uninitialized [-Wmaybe-uninitialized] 5245 | devices_info[ndevs].dev_offset = dev_offset; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~ fs/btrfs/volumes.c: In function ‘btrfs_create_chunk’: fs/btrfs/volumes.c:5196:13: note: ‘dev_offset’ was declared here 5196 | u64 dev_offset; This occurs because find_free_dev_extent is responsible for setting dev_offset, however if we get an -ENOMEM at the top of the function we'll return without setting the value. This isn't actually a problem because we will see the -ENOMEM in gather_device_info() and return and not use the uninitialized value, however we also just don't want the compiler warning so rework the code slightly in find_free_dev_extent() to make sure it's always setting *start and *len to avoid the compiler warning. Reported-by:
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- 20 Sep, 2023 7 commits
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Qu Wenruo authored
Commit f98b6215 ("btrfs: extent_io: do extra check for extent buffer read write functions") changed how we handle invalid extent buffer range for read_extent_buffer(). Previously if the range is invalid we just set the destination to zero, but after the patch we do nothing and error out. This can lead to smatch static checker errors like: fs/btrfs/print-tree.c:186 print_uuid_item() error: uninitialized symbol 'subvol_id'. fs/btrfs/tests/extent-io-tests.c:338 check_eb_bitmap() error: uninitialized symbol 'has'. fs/btrfs/tests/extent-io-tests.c:353 check_eb_bitmap() error: uninitialized symbol 'has'. fs/btrfs/uuid-tree.c:203 btrfs_uuid_tree_remove() error: uninitialized symbol 'read_subid'. fs/btrfs/uuid-tree.c:353 btrfs_uuid_tree_iterate() error: uninitialized symbol 'subid_le'. fs/btrfs/uuid-tree.c:72 btrfs_uuid_tree_lookup() error: uninitialized symbol 'data'. fs/btrfs/volumes.c:7415 btrfs_dev_stats_value() error: uninitialized symbol 'val'. Fix those warnings by reverting back to the old memset() behavior. By this we keep the static checker happy and would still make a lot of noise when such invalid ranges are passed in. Reported-by:
Dan Carpenter <dan.carpenter@linaro.org> Fixes: f98b6215 ("btrfs: extent_io: do extra check for extent buffer read write functions") Signed-off-by:
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Josef Bacik authored
A user reported some issues with smaller file systems that get very full. While investigating this issue I noticed that df wasn't showing 100% full, despite having 0 chunk space and having < 1MiB of available metadata space. This turns out to be an overflow issue, we're doing: total_available_metadata_space - SZ_4M < global_block_rsv_size to determine if there's not enough space to make metadata allocations, which overflows if total_available_metadata_space is < 4M. Fix this by checking to see if our available space is greater than the 4M threshold. This makes df properly report 100% usage on the file system. CC: stable@vger.kernel.org # 4.14+ Signed-off-by:
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Filipe Manana authored
When running a delayed extent operation, if we don't find the extent item in the extent tree we just return -EIO without any logged message. This indicates some bug or possibly a memory or fs corruption, so the return value should not be -EIO but -EUCLEAN instead, and since it's not expected to ever happen, print an informative error message so that if it happens we have some idea of what went wrong, where to look at. Reviewed-by:
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Filipe Manana authored
At __btrfs_inc_extent_ref() we are doing a BUG_ON() if we are dealing with a tree block reference that has a reference count that is different from 1, but we have already dealt with this case at run_delayed_tree_ref(), making it useless. So remove the BUG_ON(). Reviewed-by:
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Filipe Manana authored
When running a delayed tree reference, if we find a ref count different from 1, we return -EIO. This isn't an IO error, as it indicates either a bug in the delayed refs code or a memory corruption, so change the error code from -EIO to -EUCLEAN. Also tag the branch as 'unlikely' as this is not expected to ever happen, and change the error message to print the tree block's bytenr without the parenthesis (and there was a missing space between the 'block' word and the opening parenthesis), for consistency as that's the style we used everywhere else. Reviewed-by:
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Filipe Manana authored
When starting a transaction, with a non-zero number of items, we reserve metadata space for that number of items and for delayed refs by doing a call to btrfs_block_rsv_add(), with the transaction block reserve passed as the block reserve argument. This reserves metadata space and adds it to the transaction block reserve. Later we migrate the space we reserved for delayed references from the transaction block reserve into the delayed refs block reserve, by calling btrfs_migrate_to_delayed_refs_rsv(). btrfs_migrate_to_delayed_refs_rsv() decrements the number of bytes to migrate from the source block reserve, and this however may result in an underflow in case the space added to the transaction block reserve ended up being used by another task that has not reserved enough space for its own use - examples are tasks doing reflinks or hole punching because they end up calling btrfs_replace_file_extents() -> btrfs_drop_extents() and may need to modify/COW a variable number of leaves/paths, so they keep trying to use space from the transaction block reserve when they need to COW an extent buffer, and may end up trying to use more space then they have reserved (1 unit/path only for removing file extent items). This can be avoided by simply reserving space first without adding it to the transaction block reserve, then add the space for delayed refs to the delayed refs block reserve and finally add the remaining reserved space to the transaction block reserve. This also makes the code a bit shorter and simpler. So just do that. Reviewed-by:
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Filipe Manana authored
If we have two (or more) tasks attempting to refill the delayed refs block reserve we can end up with the delayed block reserve being over reserved, that is, with a reserved space greater than its size. If this happens, we are holding to more reserved space than necessary for a while. The race happens like this: 1) The delayed refs block reserve has a size of 8M and a reserved space of 6M for example; 2) Task A calls btrfs_delayed_refs_rsv_refill(); 3) Task B also calls btrfs_delayed_refs_rsv_refill(); 4) Task A sees there's a 2M difference between the size and the reserved space of the delayed refs rsv, so it will reserve 2M of space by calling btrfs_reserve_metadata_bytes(); 5) Task B also sees that 2M difference, and like task A, it reserves another 2M of metadata space; 6) Both task A and task B increase the reserved space of block reserve by 2M, by calling btrfs_block_rsv_add_bytes(), so the block reserve ends up with a size of 8M and a reserved space of 10M; 7) The extra, over reserved space will eventually be freed by some task calling btrfs_delayed_refs_rsv_release() -> btrfs_block_rsv_release() -> block_rsv_release_bytes(), as there we will detect the over reserve and release that space. So fix this by checking if we still need to add space to the delayed refs block reserve after reserving the metadata space, and if we don't, just release that space immediately. Signed-off-by:
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- 14 Sep, 2023 3 commits
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Filipe Manana authored
When opening a directory (opendir(3)) or rewinding it (rewinddir(3)), we are not holding the directory's inode locked, and this can result in later attempting to add two entries to the directory with the same index number, resulting in a transaction abort, with -EEXIST (-17), when inserting the second delayed dir index. This results in a trace like the following: Sep 11 22:34:59 myhostname kernel: BTRFS error (device dm-3): err add delayed dir index item(name: cockroach-stderr.log) into the insertion tree of the delayed node(root id: 5, inode id: 4539217, errno: -17) Sep 11 22:34:59 myhostname kernel: ------------[ cut here ]------------ Sep 11 22:34:59 myhostname kernel: kernel BUG at fs/btrfs/delayed-inode.c:1504! Sep 11 22:34:59 myhostname kernel: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI Sep 11 22:34:59 myhostname kernel: CPU: 0 PID: 7159 Comm: cockroach Not tainted 6.4.15-200.fc38.x86_64 #1 Sep 11 22:34:59 myhostname kernel: Hardware name: ASUS ESC500 G3/P9D WS, BIOS 2402 06/27/2018 Sep 11 22:34:59 myhostname kernel: RIP: 0010:btrfs_insert_delayed_dir_index+0x1da/0x260 Sep 11 22:34:59 myhostname kernel: Code: eb dd 48 (...) Sep 11 22:34:59 myhostname kernel: RSP: 0000:ffffa9980e0fbb28 EFLAGS: 00010282 Sep 11 22:34:59 myhostname kernel: RAX: 0000000000000000 RBX: ffff8b10b8f4a3c0 RCX: 0000000000000000 Sep 11 22:34:59 myhostname kernel: RDX: 0000000000000000 RSI: ffff8b177ec21540 RDI: ffff8b177ec21540 Sep 11 22:34:59 myhostname kernel: RBP: ffff8b110cf80888 R08: 0000000000000000 R09: ffffa9980e0fb938 Sep 11 22:34:59 myhostname kernel: R10: 0000000000000003 R11: ffffffff86146508 R12: 0000000000000014 Sep 11 22:34:59 myhostname kernel: R13: ffff8b1131ae5b40 R14: ffff8b10b8f4a418 R15: 00000000ffffffef Sep 11 22:34:59 myhostname kernel: FS: 00007fb14a7fe6c0(0000) GS:ffff8b177ec00000(0000) knlGS:0000000000000000 Sep 11 22:34:59 myhostname kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Sep 11 22:34:59 myhostname kernel: CR2: 000000c00143d000 CR3: 00000001b3b4e002 CR4: 00000000001706f0 Sep 11 22:34:59 myhostname kernel: Call Trace: Sep 11 22:34:59 myhostname kernel: <TASK> Sep 11 22:34:59 myhostname kernel: ? die+0x36/0x90 Sep 11 22:34:59 myhostname kernel: ? do_trap+0xda/0x100 Sep 11 22:34:59 myhostname kernel: ? btrfs_insert_delayed_dir_index+0x1da/0x260 Sep 11 22:34:59 myhostname kernel: ? do_error_trap+0x6a/0x90 Sep 11 22:34:59 myhostname kernel: ? btrfs_insert_delayed_dir_index+0x1da/0x260 Sep 11 22:34:59 myhostname kernel: ? exc_invalid_op+0x50/0x70 Sep 11 22:34:59 myhostname kernel: ? btrfs_insert_delayed_dir_index+0x1da/0x260 Sep 11 22:34:59 myhostname kernel: ? asm_exc_invalid_op+0x1a/0x20 Sep 11 22:34:59 myhostname kernel: ? btrfs_insert_delayed_dir_index+0x1da/0x260 Sep 11 22:34:59 myhostname kernel: ? btrfs_insert_delayed_dir_index+0x1da/0x260 Sep 11 22:34:59 myhostname kernel: btrfs_insert_dir_item+0x200/0x280 Sep 11 22:34:59 myhostname kernel: btrfs_add_link+0xab/0x4f0 Sep 11 22:34:59 myhostname kernel: ? ktime_get_real_ts64+0x47/0xe0 Sep 11 22:34:59 myhostname kernel: btrfs_create_new_inode+0x7cd/0xa80 Sep 11 22:34:59 myhostname kernel: btrfs_symlink+0x190/0x4d0 Sep 11 22:34:59 myhostname kernel: ? schedule+0x5e/0xd0 Sep 11 22:34:59 myhostname kernel: ? __d_lookup+0x7e/0xc0 Sep 11 22:34:59 myhostname kernel: vfs_symlink+0x148/0x1e0 Sep 11 22:34:59 myhostname kernel: do_symlinkat+0x130/0x140 Sep 11 22:34:59 myhostname kernel: __x64_sys_symlinkat+0x3d/0x50 Sep 11 22:34:59 myhostname kernel: do_syscall_64+0x5d/0x90 Sep 11 22:34:59 myhostname kernel: ? syscall_exit_to_user_mode+0x2b/0x40 Sep 11 22:34:59 myhostname kernel: ? do_syscall_64+0x6c/0x90 Sep 11 22:34:59 myhostname kernel: entry_SYSCALL_64_after_hwframe+0x72/0xdc The race leading to the problem happens like this: 1) Directory inode X is loaded into memory, its ->index_cnt field is initialized to (u64)-1 (at btrfs_alloc_inode()); 2) Task A is adding a new file to directory X, holding its vfs inode lock, and calls btrfs_set_inode_index() to get an index number for the entry. Because the inode's index_cnt field is set to (u64)-1 it calls btrfs_inode_delayed_dir_index_count() which fails because no dir index entries were added yet to the delayed inode and then it calls btrfs_set_inode_index_count(). This functions finds the last dir index key and then sets index_cnt to that index value + 1. It found that the last index key has an offset of 100. However before it assigns a value of 101 to index_cnt... 3) Task B calls opendir(3), ending up at btrfs_opendir(), where the VFS lock for inode X is not taken, so it calls btrfs_get_dir_last_index() and sees index_cnt still with a value of (u64)-1. Because of that it calls btrfs_inode_delayed_dir_index_count() which fails since no dir index entries were added to the delayed inode yet, and then it also calls btrfs_set_inode_index_count(). This also finds that the last index key has an offset of 100, and before it assigns the value 101 to the index_cnt field of inode X... 4) Task A assigns a value of 101 to index_cnt. And then the code flow goes to btrfs_set_inode_index() where it increments index_cnt from 101 to 102. Task A then creates a delayed dir index entry with a sequence number of 101 and adds it to the delayed inode; 5) Task B assigns 101 to the index_cnt field of inode X; 6) At some later point when someone tries to add a new entry to the directory, btrfs_set_inode_index() will return 101 again and shortly after an attempt to add another delayed dir index key with index number 101 will fail with -EEXIST resulting in a transaction abort. Fix this by locking the inode at btrfs_get_dir_last_index(), which is only only used when opening a directory or attempting to lseek on it. Reported-by:
ken <ken@bllue.org> Link: https://lore.kernel.org/linux-btrfs/CAE6xmH+Lp=Q=E61bU+v9eWX8gYfLvu6jLYxjxjFpo3zHVPR0EQ@mail.gmail.com/ Reported-by: syzbot+d13490c82ad5353c779d@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/00000000000036e1290603e097e0@google.com/ Fixes: 9b378f6a ("btrfs: fix infinite directory reads") CC: stable@vger.kernel.org # 6.5+ Signed-off-by:
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Filipe Manana authored
When opening a directory we find what's the index of its last entry and then store it in the directory's file handle private data (struct btrfs_file_private::last_index), so that in the case new directory entries are added to a directory after an opendir(3) call we don't end up in an infinite loop (see commit 9b378f6a ("btrfs: fix infinite directory reads")) when calling readdir(3). However once rewinddir(3) is called, POSIX states [1] that any new directory entries added after the previous opendir(3) call, must be returned by subsequent calls to readdir(3): "The rewinddir() function shall reset the position of the directory stream to which dirp refers to the beginning of the directory. It shall also cause the directory stream to refer to the current state of the corresponding directory, as a call to opendir() would have done." We currently don't refresh the last_index field of the struct btrfs_file_private associated to the directory, so after a rewinddir(3) we are not returning any new entries added after the opendir(3) call. Fix this by finding the current last index of the directory when llseek is called against the directory. This can be reproduced by the following C program provided by Ian Johnson: #include <dirent.h> #include <stdio.h> int main(void) { DIR *dir = opendir("test"); FILE *file; file = fopen("test/1", "w"); fwrite("1", 1, 1, file); fclose(file); file = fopen("test/2", "w"); fwrite("2", 1, 1, file); fclose(file); rewinddir(dir); struct dirent *entry; while ((entry = readdir(dir))) { printf("%s\n", entry->d_name); } closedir(dir); return 0; } Reported-by:
Ian Johnson <ian@ianjohnson.dev> Link: https://lore.kernel.org/linux-btrfs/YR1P0S.NGASEG570GJ8@ianjohnson.dev/ Fixes: 9b378f6a ("btrfs: fix infinite directory reads") CC: stable@vger.kernel.org # 6.5+ Signed-off-by:
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Filipe Manana authored
When opening a directory for reading it, we set the last index where we stop iteration to the value in struct btrfs_inode::index_cnt. That value does not match the index of the most recently added directory entry but it's instead the index number that will be assigned the next directory entry. This means that if after the call to opendir(3) new directory entries are added, a readdir(3) call will return the first new directory entry. This is fine because POSIX says the following [1]: "If a file is removed from or added to the directory after the most recent call to opendir() or rewinddir(), whether a subsequent call to readdir() returns an entry for that file is unspecified." For example for the test script from commit 9b378f6a ("btrfs: fix infinite directory reads"), where we have 2000 files in a directory, ext4 doesn't return any new directory entry after opendir(3), while xfs returns the first 13 new directory entries added after the opendir(3) call. If we move to a shorter example with an empty directory when opendir(3) is called, and 2 files added to the directory after the opendir(3) call, then readdir(3) on btrfs will return the first file, ext4 and xfs return the 2 files (but in a different order). A test program for this, reported by Ian Johnson, is the following: #include <dirent.h> #include <stdio.h> int main(void) { DIR *dir = opendir("test"); FILE *file; file = fopen("test/1", "w"); fwrite("1", 1, 1, file); fclose(file); file = fopen("test/2", "w"); fwrite("2", 1, 1, file); fclose(file); struct dirent *entry; while ((entry = readdir(dir))) { printf("%s\n", entry->d_name); } closedir(dir); return 0; } To make this less odd, change the behaviour to never return new entries that were added after the opendir(3) call. This is done by setting the last_index field of the struct btrfs_file_private attached to the directory's file handle with a value matching btrfs_inode::index_cnt minus 1, since that value always matches the index of the next new directory entry and not the index of the most recently added entry. [1] https://pubs.opengroup.org/onlinepubs/007904875/functions/readdir_r.html Link: https://lore.kernel.org/linux-btrfs/YR1P0S.NGASEG570GJ8@ianjohnson.dev/ CC: stable@vger.kernel.org # 6.5+ Signed-off-by:
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- 13 Sep, 2023 3 commits
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Josef Bacik authored
We have been consistently seeing hangs with generic/648 in our subpage GitHub CI setup. This is a classic deadlock, we are calling btrfs_read_folio() on a folio, which requires holding the folio lock on the folio, and then finding a ordered extent that overlaps that range and calling btrfs_start_ordered_extent(), which then tries to write out the dirty page, which requires taking the folio lock and then we deadlock. The hang happens because we're writing to range [1271750656, 1271767040), page index [77621, 77622], and page 77621 is !Uptodate. It is also Dirty, so we call btrfs_read_folio() for 77621 and which does btrfs_lock_and_flush_ordered_range() for that range, and we find an ordered extent which is [1271644160, 1271746560), page index [77615, 77621]. The page indexes overlap, but the actual bytes don't overlap. We're holding the page lock for 77621, then call btrfs_lock_and_flush_ordered_range() which tries to flush the dirty page, and tries to lock 77621 again and then we deadlock. The byte ranges do not overlap, but with subpage support if we clear uptodate on any portion of the page we mark the entire thing as not uptodate. We have been clearing page uptodate on write errors, but no other file system does this, and is in fact incorrect. This doesn't hurt us in the !subpage case because we can't end up with overlapped ranges that don't also overlap on the page. Fix this by not clearing uptodate when we have a write error. The only thing we should be doing in this case is setting the mapping error and carrying on. This makes it so we would no longer call btrfs_read_folio() on the page as it's uptodate and eliminates the deadlock. With this patch we're now able to make it through a full fstests run on our subpage blocksize VMs. Note for stable backports: this probably goes beyond 6.1 but the code has been cleaned up and clearing the uptodate bit must be verified on each version independently. CC: stable@vger.kernel.org # 6.1+ Reviewed-by:
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Bernd Schubert authored
This was noticed by Miklos that file_remove_privs might call into notify_change(), which requires to hold an exclusive lock. The problem exists in FUSE and btrfs. We can fix it without any additional helpers from VFS, in case the privileges would need to be dropped, change the lock type to be exclusive and redo the loop. Fixes: e9adabb9 ("btrfs: use shared lock for direct writes within EOF") CC: Miklos Szeredi <miklos@szeredi.hu> CC: stable@vger.kernel.org # 5.15+ Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Bernd Schubert <bschubert@ddn.com> Reviewed-by:
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Matthew Wilcox (Oracle) authored
Remove a number of hidden calls to compound_head() by using a folio throughout. Also follow core kernel coding style by adding the folio to the page cache immediately after allocation instead of doing the read first, then adding it to the page cache. This ordering makes subsequent readers block waiting for the first reader instead of duplicating the work only to throw it away when they find out they lost the race. Reviewed-by:
Boris Burkov <boris@bur.io> Signed-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by:
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- 08 Sep, 2023 10 commits
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Bhaskar Chowdhury authored
The wiki has been archived and is not updated anymore. Remove or replace the links in files that contain it (MAINTAINERS, Kconfig, docs). Signed-off-by:
Bhaskar Chowdhury <unixbhaskar@gmail.com> Reviewed-by:
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Filipe Manana authored
When removing a delayed item, or releasing which will remove it as well, we will modify one of the delayed node's rbtrees and item counter if the delayed item is in one of the rbtrees. This require having the delayed node's mutex locked, otherwise we will race with other tasks modifying the rbtrees and the counter. This is motivated by a previous version of another patch actually calling btrfs_release_delayed_item() after unlocking the delayed node's mutex and against a delayed item that is in a rbtree. So assert at __btrfs_remove_delayed_item() that the delayed node's mutex is locked. Reviewed-by:
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Filipe Manana authored
Instead of calling BUG() when we fail to insert a delayed dir index item into the delayed node's tree, we can just release all the resources we have allocated/acquired before and return the error to the caller. This is fine because all existing call chains undo anything they have done before calling btrfs_insert_delayed_dir_index() or BUG_ON (when creating pending snapshots in the transaction commit path). So remove the BUG() call and do proper error handling. This relates to a syzbot report linked below, but does not fix it because it only prevents hitting a BUG(), it does not fix the issue where somehow we attempt to use twice the same index number for different index items. Link: https://lore.kernel.org/linux-btrfs/00000000000036e1290603e097e0@google.com/ CC: stable@vger.kernel.org # 5.4+ Reviewed-by:
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Filipe Manana authored
If we fail to add a delayed dir index item because there's already another item with the same index number, we print an error message (and then BUG). However that message isn't very helpful to debug anything because we don't know what's the index number and what are the values of index counters in the inode and its delayed inode (index_cnt fields of struct btrfs_inode and struct btrfs_delayed_node). So update the error message to include the index number and counters. We actually had a recent case where this issue was hit by a syzbot report (see the link below). Link: https://lore.kernel.org/linux-btrfs/00000000000036e1290603e097e0@google.com/Reviewed-by:
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Qu Wenruo authored
[BUG] After commit 72a69cd0 ("btrfs: subpage: pack all subpage bitmaps into a larger bitmap"), the DEBUG section of btree_dirty_folio() would no longer compile. [CAUSE] If DEBUG is defined, we would do extra checks for btree_dirty_folio(), mostly to make sure the range we marked dirty has an extent buffer and that extent buffer is dirty. For subpage, we need to iterate through all the extent buffers covered by that page range, and make sure they all matches the criteria. However commit 72a69cd0 ("btrfs: subpage: pack all subpage bitmaps into a larger bitmap") changes how we store the bitmap, we pack all the 16 bits bitmaps into a larger bitmap, which would save some space. This means we no longer have btrfs_subpage::dirty_bitmap, instead the dirty bitmap is starting at btrfs_subpage_info::dirty_offset, and has a length of btrfs_subpage_info::bitmap_nr_bits. [FIX] Although I'm not sure if it still makes sense to maintain such code, at least let it compile. This patch would let us test the bits one by one through the bitmaps. CC: stable@vger.kernel.org # 6.1+ Signed-off-by:
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Josef Bacik authored
If we do fast tree logging we increment a counter on the current transaction for every ordered extent we need to wait for. This means we expect the transaction to still be there when we clear pending on the ordered extent. However if we happen to abort the transaction and clean it up, there could be no running transaction, and thus we'll trip the "ASSERT(trans)" check. This is obviously incorrect, and the code properly deals with the case that the transaction doesn't exist. Fix this ASSERT() to only fire if there's no trans and we don't have BTRFS_FS_ERROR() set on the file system. CC: stable@vger.kernel.org # 4.14+ Reviewed-by:
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Filipe Manana authored
When running delayed items we are holding a delayed node's mutex and then we will attempt to modify a subvolume btree to insert/update/delete the delayed items. However if have an error during the insertions for example, btrfs_insert_delayed_items() may return with a path that has locked extent buffers (a leaf at the very least), and then we attempt to release the delayed node at __btrfs_run_delayed_items(), which requires taking the delayed node's mutex, causing an ABBA type of deadlock. This was reported by syzbot and the lockdep splat is the following: WARNING: possible circular locking dependency detected 6.5.0-rc7-syzkaller-00024-g93f5de5f #0 Not tainted ------------------------------------------------------ syz-executor.2/13257 is trying to acquire lock: ffff88801835c0c0 (&delayed_node->mutex){+.+.}-{3:3}, at: __btrfs_release_delayed_node+0x9a/0xaa0 fs/btrfs/delayed-inode.c:256 but task is already holding lock: ffff88802a5ab8e8 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_lock+0x3c/0x2a0 fs/btrfs/locking.c:198 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (btrfs-tree-00){++++}-{3:3}: __lock_release kernel/locking/lockdep.c:5475 [inline] lock_release+0x36f/0x9d0 kernel/locking/lockdep.c:5781 up_write+0x79/0x580 kernel/locking/rwsem.c:1625 btrfs_tree_unlock_rw fs/btrfs/locking.h:189 [inline] btrfs_unlock_up_safe+0x179/0x3b0 fs/btrfs/locking.c:239 search_leaf fs/btrfs/ctree.c:1986 [inline] btrfs_search_slot+0x2511/0x2f80 fs/btrfs/ctree.c:2230 btrfs_insert_empty_items+0x9c/0x180 fs/btrfs/ctree.c:4376 btrfs_insert_delayed_item fs/btrfs/delayed-inode.c:746 [inline] btrfs_insert_delayed_items fs/btrfs/delayed-inode.c:824 [inline] __btrfs_commit_inode_delayed_items+0xd24/0x2410 fs/btrfs/delayed-inode.c:1111 __btrfs_run_delayed_items+0x1db/0x430 fs/btrfs/delayed-inode.c:1153 flush_space+0x269/0xe70 fs/btrfs/space-info.c:723 btrfs_async_reclaim_metadata_space+0x106/0x350 fs/btrfs/space-info.c:1078 process_one_work+0x92c/0x12c0 kernel/workqueue.c:2600 worker_thread+0xa63/0x1210 kernel/workqueue.c:2751 kthread+0x2b8/0x350 kernel/kthread.c:389 ret_from_fork+0x2e/0x60 arch/x86/kernel/process.c:145 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 -> #0 (&delayed_node->mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3142 [inline] check_prevs_add kernel/locking/lockdep.c:3261 [inline] validate_chain kernel/locking/lockdep.c:3876 [inline] __lock_acquire+0x39ff/0x7f70 kernel/locking/lockdep.c:5144 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5761 __mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 __btrfs_release_delayed_node+0x9a/0xaa0 fs/btrfs/delayed-inode.c:256 btrfs_release_delayed_node fs/btrfs/delayed-inode.c:281 [inline] __btrfs_run_delayed_items+0x2b5/0x430 fs/btrfs/delayed-inode.c:1156 btrfs_commit_transaction+0x859/0x2ff0 fs/btrfs/transaction.c:2276 btrfs_sync_file+0xf56/0x1330 fs/btrfs/file.c:1988 vfs_fsync_range fs/sync.c:188 [inline] vfs_fsync fs/sync.c:202 [inline] do_fsync fs/sync.c:212 [inline] __do_sys_fsync fs/sync.c:220 [inline] __se_sys_fsync fs/sync.c:218 [inline] __x64_sys_fsync+0x196/0x1e0 fs/sync.c:218 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(btrfs-tree-00); lock(&delayed_node->mutex); lock(btrfs-tree-00); lock(&delayed_node->mutex); *** DEADLOCK *** 3 locks held by syz-executor.2/13257: #0: ffff88802c1ee370 (btrfs_trans_num_writers){++++}-{0:0}, at: spin_unlock include/linux/spinlock.h:391 [inline] #0: ffff88802c1ee370 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0xb87/0xe00 fs/btrfs/transaction.c:287 #1: ffff88802c1ee398 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0xbb2/0xe00 fs/btrfs/transaction.c:288 #2: ffff88802a5ab8e8 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_lock+0x3c/0x2a0 fs/btrfs/locking.c:198 stack backtrace: CPU: 0 PID: 13257 Comm: syz-executor.2 Not tainted 6.5.0-rc7-syzkaller-00024-g93f5de5f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 check_noncircular+0x375/0x4a0 kernel/locking/lockdep.c:2195 check_prev_add kernel/locking/lockdep.c:3142 [inline] check_prevs_add kernel/locking/lockdep.c:3261 [inline] validate_chain kernel/locking/lockdep.c:3876 [inline] __lock_acquire+0x39ff/0x7f70 kernel/locking/lockdep.c:5144 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5761 __mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 __btrfs_release_delayed_node+0x9a/0xaa0 fs/btrfs/delayed-inode.c:256 btrfs_release_delayed_node fs/btrfs/delayed-inode.c:281 [inline] __btrfs_run_delayed_items+0x2b5/0x430 fs/btrfs/delayed-inode.c:1156 btrfs_commit_transaction+0x859/0x2ff0 fs/btrfs/transaction.c:2276 btrfs_sync_file+0xf56/0x1330 fs/btrfs/file.c:1988 vfs_fsync_range fs/sync.c:188 [inline] vfs_fsync fs/sync.c:202 [inline] do_fsync fs/sync.c:212 [inline] __do_sys_fsync fs/sync.c:220 [inline] __se_sys_fsync fs/sync.c:218 [inline] __x64_sys_fsync+0x196/0x1e0 fs/sync.c:218 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f3ad047cae9 Code: 28 00 00 00 75 (...) RSP: 002b:00007f3ad12510c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004a RAX: ffffffffffffffda RBX: 00007f3ad059bf80 RCX: 00007f3ad047cae9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 00007f3ad04c847a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f3ad059bf80 R15: 00007ffe56af92f8 </TASK> ------------[ cut here ]------------ Fix this by releasing the path before releasing the delayed node in the error path at __btrfs_run_delayed_items(). Reported-by: syzbot+a379155f07c134ea9879@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/000000000000abba27060403b5bd@google.com/ CC: stable@vger.kernel.org # 4.14+ Signed-off-by:
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Josef Bacik authored
Internally I got a report of very long stalls on normal operations like creating a new file when auto relocation was running. The reporter used the 'bpf offcputime' tracer to show that we would get stuck in start_transaction for 5 to 30 seconds, and were always being woken up by the transaction commit. Using my timing-everything script, which times how long a function takes and what percentage of that total time is taken up by its children, I saw several traces like this 1083 took 32812902424 ns 29929002926 ns 91.2110% wait_for_commit_duration 25568 ns 7.7920e-05% commit_fs_roots_duration 1007751 ns 0.00307% commit_cowonly_roots_duration 446855602 ns 1.36182% btrfs_run_delayed_refs_duration 271980 ns 0.00082% btrfs_run_delayed_items_duration 2008 ns 6.1195e-06% btrfs_apply_pending_changes_duration 9656 ns 2.9427e-05% switch_commit_roots_duration 1598 ns 4.8700e-06% btrfs_commit_device_sizes_duration 4314 ns 1.3147e-05% btrfs_free_log_root_tree_duration Here I was only tracing functions that happen where we are between START_COMMIT and UNBLOCKED in order to see what would be keeping us blocked for so long. The wait_for_commit() we do is where we wait for a previous transaction that hasn't completed it's commit. This can include all of the unpin work and other cleanups, which tends to be the longest part of our transaction commit. There is no reason we should be blocking new things from entering the transaction at this point, it just adds to random latency spikes for no reason. Fix this by adding a PREP stage. This allows us to properly deal with multiple committers coming in at the same time, we retain the behavior that the winner waits on the previous transaction and the losers all wait for this transaction commit to occur. Nothing else is blocked during the PREP stage, and then once the wait is complete we switch to COMMIT_START and all of the same behavior as before is maintained. Reviewed-by: -
Filipe Manana authored
During the ino lookup ioctl we can end up calling btrfs_iget() to get an inode reference while we are holding on a root's btree. If btrfs_iget() needs to lookup the inode from the root's btree, because it's not currently loaded in memory, then it will need to lock another or the same path in the same root btree. This may result in a deadlock and trigger the following lockdep splat: WARNING: possible circular locking dependency detected 6.5.0-rc7-syzkaller-00004-gf7757129 #0 Not tainted ------------------------------------------------------ syz-executor277/5012 is trying to acquire lock: ffff88802df41710 (btrfs-tree-01){++++}-{3:3}, at: __btrfs_tree_read_lock+0x2f/0x220 fs/btrfs/locking.c:136 but task is already holding lock: ffff88802df418e8 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x2f/0x220 fs/btrfs/locking.c:136 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (btrfs-tree-00){++++}-{3:3}: down_read_nested+0x49/0x2f0 kernel/locking/rwsem.c:1645 __btrfs_tree_read_lock+0x2f/0x220 fs/btrfs/locking.c:136 btrfs_search_slot+0x13a4/0x2f80 fs/btrfs/ctree.c:2302 btrfs_init_root_free_objectid+0x148/0x320 fs/btrfs/disk-io.c:4955 btrfs_init_fs_root fs/btrfs/disk-io.c:1128 [inline] btrfs_get_root_ref+0x5ae/0xae0 fs/btrfs/disk-io.c:1338 btrfs_get_fs_root fs/btrfs/disk-io.c:1390 [inline] open_ctree+0x29c8/0x3030 fs/btrfs/disk-io.c:3494 btrfs_fill_super+0x1c7/0x2f0 fs/btrfs/super.c:1154 btrfs_mount_root+0x7e0/0x910 fs/btrfs/super.c:1519 legacy_get_tree+0xef/0x190 fs/fs_context.c:611 vfs_get_tree+0x8c/0x270 fs/super.c:1519 fc_mount fs/namespace.c:1112 [inline] vfs_kern_mount+0xbc/0x150 fs/namespace.c:1142 btrfs_mount+0x39f/0xb50 fs/btrfs/super.c:1579 legacy_get_tree+0xef/0x190 fs/fs_context.c:611 vfs_get_tree+0x8c/0x270 fs/super.c:1519 do_new_mount+0x28f/0xae0 fs/namespace.c:3335 do_mount fs/namespace.c:3675 [inline] __do_sys_mount fs/namespace.c:3884 [inline] __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (btrfs-tree-01){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3142 [inline] check_prevs_add kernel/locking/lockdep.c:3261 [inline] validate_chain kernel/locking/lockdep.c:3876 [inline] __lock_acquire+0x39ff/0x7f70 kernel/locking/lockdep.c:5144 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5761 down_read_nested+0x49/0x2f0 kernel/locking/rwsem.c:1645 __btrfs_tree_read_lock+0x2f/0x220 fs/btrfs/locking.c:136 btrfs_tree_read_lock fs/btrfs/locking.c:142 [inline] btrfs_read_lock_root_node+0x292/0x3c0 fs/btrfs/locking.c:281 btrfs_search_slot_get_root fs/btrfs/ctree.c:1832 [inline] btrfs_search_slot+0x4ff/0x2f80 fs/btrfs/ctree.c:2154 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:412 btrfs_read_locked_inode fs/btrfs/inode.c:3892 [inline] btrfs_iget_path+0x2d9/0x1520 fs/btrfs/inode.c:5716 btrfs_search_path_in_tree_user fs/btrfs/ioctl.c:1961 [inline] btrfs_ioctl_ino_lookup_user+0x77a/0xf50 fs/btrfs/ioctl.c:2105 btrfs_ioctl+0xb0b/0xd40 fs/btrfs/ioctl.c:4683 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(btrfs-tree-00); lock(btrfs-tree-01); lock(btrfs-tree-00); rlock(btrfs-tree-01); *** DEADLOCK *** 1 lock held by syz-executor277/5012: #0: ffff88802df418e8 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x2f/0x220 fs/btrfs/locking.c:136 stack backtrace: CPU: 1 PID: 5012 Comm: syz-executor277 Not tainted 6.5.0-rc7-syzkaller-00004-gf7757129 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 check_noncircular+0x375/0x4a0 kernel/locking/lockdep.c:2195 check_prev_add kernel/locking/lockdep.c:3142 [inline] check_prevs_add kernel/locking/lockdep.c:3261 [inline] validate_chain kernel/locking/lockdep.c:3876 [inline] __lock_acquire+0x39ff/0x7f70 kernel/locking/lockdep.c:5144 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5761 down_read_nested+0x49/0x2f0 kernel/locking/rwsem.c:1645 __btrfs_tree_read_lock+0x2f/0x220 fs/btrfs/locking.c:136 btrfs_tree_read_lock fs/btrfs/locking.c:142 [inline] btrfs_read_lock_root_node+0x292/0x3c0 fs/btrfs/locking.c:281 btrfs_search_slot_get_root fs/btrfs/ctree.c:1832 [inline] btrfs_search_slot+0x4ff/0x2f80 fs/btrfs/ctree.c:2154 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:412 btrfs_read_locked_inode fs/btrfs/inode.c:3892 [inline] btrfs_iget_path+0x2d9/0x1520 fs/btrfs/inode.c:5716 btrfs_search_path_in_tree_user fs/btrfs/ioctl.c:1961 [inline] btrfs_ioctl_ino_lookup_user+0x77a/0xf50 fs/btrfs/ioctl.c:2105 btrfs_ioctl+0xb0b/0xd40 fs/btrfs/ioctl.c:4683 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f0bec94ea39 Fix this simply by releasing the path before calling btrfs_iget() as at point we don't need the path anymore. Reported-by: syzbot+bf66ad948981797d2f1d@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/00000000000045fa140603c4a969@google.com/ Fixes: 23d0b79d ("btrfs: Add unprivileged version of ino_lookup ioctl") CC: stable@vger.kernel.org # 4.19+ Reviewed-by:
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Filipe Manana authored
Commit 675dfe12 ("btrfs: fix block group item corruption after inserting new block group") fixed one race that resulted in not persisting a block group's item when its "used" bytes field decreases to zero. However there's another race that can happen in a much shorter time window that results in the same problem. The following sequence of steps explains how it can happen: 1) Task A creates a metadata block group X, its "used" and "commit_used" fields are initialized to 0; 2) Two extents are allocated from block group X, so its "used" field is updated to 32K, and its "commit_used" field remains as 0; 3) Transaction commit starts, by some task B, and it enters btrfs_start_dirty_block_groups(). There it tries to update the block group item for block group X, which currently has its "used" field with a value of 32K and its "commit_used" field with a value of 0. However that fails since the block group item was not yet inserted, so at update_block_group_item(), the btrfs_search_slot() call returns 1, and then we set 'ret' to -ENOENT. Before jumping to the label 'fail'... 4) The block group item is inserted by task A, when for example btrfs_create_pending_block_groups() is called when releasing its transaction handle. This results in insert_block_group_item() inserting the block group item in the extent tree (or block group tree), with a "used" field having a value of 32K and setting "commit_used", in struct btrfs_block_group, to the same value (32K); 5) Task B jumps to the 'fail' label and then resets the "commit_used" field to 0. At btrfs_start_dirty_block_groups(), because -ENOENT was returned from update_block_group_item(), we add the block group again to the list of dirty block groups, so that we will try again in the critical section of the transaction commit when calling btrfs_write_dirty_block_groups(); 6) Later the two extents from block group X are freed, so its "used" field becomes 0; 7) If no more extents are allocated from block group X before we get into btrfs_write_dirty_block_groups(), then when we call update_block_group_item() again for block group X, we will not update the block group item to reflect that it has 0 bytes used, because the "used" and "commit_used" fields in struct btrfs_block_group have the same value, a value of 0. As a result after committing the transaction we have an empty block group with its block group item having a 32K value for its "used" field. This will trigger errors from fsck ("btrfs check" command) and after mounting again the fs, the cleaner kthread will not automatically delete the empty block group, since its "used" field is not 0. Possibly there are other issues due to this inconsistency. When this issue happens, the error reported by fsck is like this: [1/7] checking root items [2/7] checking extents block group [1104150528 1073741824] used 39796736 but extent items used 0 ERROR: errors found in extent allocation tree or chunk allocation (...) So fix this by not resetting the "commit_used" field of a block group when we don't find the block group item at update_block_group_item(). Fixes: 7248e0ce ("btrfs: skip update of block group item if used bytes are the same") CC: stable@vger.kernel.org # 6.2+ Reviewed-by:
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- 22 Aug, 2023 1 commit
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Naohiro Aota authored
When doing a relocation, there is a chance that at the time of btrfs_reloc_clone_csums(), there is no checksum for the corresponding region. In this case, btrfs_finish_ordered_zoned()'s sum points to an invalid item and so ordered_extent's logical is set to some invalid value. Then, btrfs_lookup_block_group() in btrfs_zone_finish_endio() failed to find a block group and will hit an assert or a null pointer dereference as following. This can be reprodcued by running btrfs/028 several times (e.g, 4 to 16 times) with a null_blk setup. The device's zone size and capacity is set to 32 MB and the storage size is set to 5 GB on my setup. KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f] CPU: 6 PID: 3105720 Comm: kworker/u16:13 Tainted: G W 6.5.0-rc6-kts+ #1 Hardware name: Supermicro Super Server/X10SRL-F, BIOS 2.0 12/17/2015 Workqueue: btrfs-endio-write btrfs_work_helper [btrfs] RIP: 0010:btrfs_zone_finish_endio.part.0+0x34/0x160 [btrfs] Code: 41 54 49 89 fc 55 48 89 f5 53 e8 57 7d fc ff 48 8d b8 88 00 00 00 48 89 c3 48 b8 00 00 00 00 00 > 3c 02 00 0f 85 02 01 00 00 f6 83 88 00 00 00 01 0f 84 a8 00 00 RSP: 0018:ffff88833cf87b08 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000011 RSI: 0000000000000004 RDI: 0000000000000088 RBP: 0000000000000002 R08: 0000000000000001 R09: ffffed102877b827 R10: ffff888143bdc13b R11: ffff888125b1cbc0 R12: ffff888143bdc000 R13: 0000000000007000 R14: ffff888125b1cba8 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88881e500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3ed85223d5 CR3: 00000001519b4005 CR4: 00000000001706e0 Call Trace: <TASK> ? die_addr+0x3c/0xa0 ? exc_general_protection+0x148/0x220 ? asm_exc_general_protection+0x22/0x30 ? btrfs_zone_finish_endio.part.0+0x34/0x160 [btrfs] ? btrfs_zone_finish_endio.part.0+0x19/0x160 [btrfs] btrfs_finish_one_ordered+0x7b8/0x1de0 [btrfs] ? rcu_is_watching+0x11/0xb0 ? lock_release+0x47a/0x620 ? btrfs_finish_ordered_zoned+0x59b/0x800 [btrfs] ? __pfx_btrfs_finish_one_ordered+0x10/0x10 [btrfs] ? btrfs_finish_ordered_zoned+0x358/0x800 [btrfs] ? __smp_call_single_queue+0x124/0x350 ? rcu_is_watching+0x11/0xb0 btrfs_work_helper+0x19f/0xc60 [btrfs] ? __pfx_try_to_wake_up+0x10/0x10 ? _raw_spin_unlock_irq+0x24/0x50 ? rcu_is_watching+0x11/0xb0 process_one_work+0x8c1/0x1430 ? __pfx_lock_acquire+0x10/0x10 ? __pfx_process_one_work+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? _raw_spin_lock_irq+0x52/0x60 worker_thread+0x100/0x12c0 ? __kthread_parkme+0xc1/0x1f0 ? __pfx_worker_thread+0x10/0x10 kthread+0x2ea/0x3c0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x30/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> On the zoned mode, writing to pre-allocated region means data relocation write. Such write always uses WRITE command so there is no need of splitting and rewriting logical address. Thus, we can just skip the function for the case. Fixes: cbfce4c7 ("btrfs: optimize the logical to physical mapping for zoned writes") Signed-off-by:Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by:
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- 21 Aug, 2023 10 commits
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Josef Bacik authored
This reproduces the bug fixed by "btrfs: fix incorrect splitting in btrfs_drop_extent_map_range", we were improperly calculating the range for the split extent. Add a test that exercises this scenario and validates that we get the correct resulting extent_maps in our tree. Reviewed-by:
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Josef Bacik authored
This helper is different from the normal add_extent_mapping in that it will stuff an em into a gap that exists between overlapping em's in the tree. It appeared there was a bug so I wrote a self test to validate it did the correct thing when it worked with two side by side ems. Thankfully it is correct, but more testing is better. Reviewed-by:
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Josef Bacik authored
While investigating weird problems with the extent_map I wrote a self test testing the various edge cases of btrfs_drop_extent_map_range. This can split in different ways and behaves different in each case, so test the various edge cases to make sure everything is functioning properly. Reviewed-by:
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Qu Wenruo authored
Currently the scrub_stripe_read_repair_worker() only does reads to rebuild the corrupted sectors, it doesn't do any writeback. The design is mostly to put writeback into a more ordered manner, to co-operate with dev-replace with zoned mode, which requires every write to be submitted in their bytenr order. However the writeback for repaired sectors into the original mirror doesn't need such strong sync requirement, as it can only happen for non-zoned devices. This patch would move the writeback for repaired sectors into scrub_stripe_read_repair_worker(), which removes two calls sites for repaired sectors writeback. (one from flush_scrub_stripes(), one from scrub_raid56_parity_stripe()) Signed-off-by:
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Qu Wenruo authored
The workqueue fs_info->scrub_worker would go ordered workqueue if it's a device replace operation. However the scrub is relying on multiple workers to do data csum verification, and we always submit several read requests in a row. Thus there is no need to use ordered workqueue just for dev-replace. We have extra synchronization (the main thread will always submit-and-wait for dev-replace writes) to handle it for zoned devices. Signed-off-by:
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Qu Wenruo authored
[REGRESSION] There are several regression reports about the scrub performance with v6.4 kernel. On a PCIe 3.0 device, the old v6.3 kernel can go 3GB/s scrub speed, but v6.4 can only go 1GB/s, an obvious 66% performance drop. [CAUSE] Iostat shows a very different behavior between v6.3 and v6.4 kernel: Device r/s rkB/s rrqm/s %rrqm r_await rareq-sz aqu-sz %util nvme0n1p3 9731.00 3425544.00 17237.00 63.92 2.18 352.02 21.18 100.00 nvme0n1p3 15578.00 993616.00 5.00 0.03 0.09 63.78 1.32 100.00 The upper one is v6.3 while the lower one is v6.4. There are several obvious differences: - Very few read merges This turns out to be a behavior change that we no longer do bio plug/unplug. - Very low aqu-sz This is due to the submit-and-wait behavior of flush_scrub_stripes(), and extra extent/csum tree search. Both behaviors are not that obvious on SATA SSDs, as SATA SSDs have NCQ to merge the reads, while SATA SSDs can not handle high queue depth well either. [FIX] For now this patch focuses on the read speed fix. Dev-replace replace speed needs more work. For the read part, we go two directions to fix the problems: - Re-introduce blk plug/unplug to merge read requests This is pretty simple, and the behavior is pretty easy to observe. This would enlarge the average read request size to 512K. - Introduce multi-group reads and no longer wait for each group Instead of the old behavior, which submits 8 stripes and waits for them, here we would enlarge the total number of stripes to 16 * 8. Which is 8M per device, the same limit as the old scrub in-flight bios size limit. Now every time we fill a group (8 stripes), we submit them and continue to next stripes. Only when the full 16 * 8 stripes are all filled, we submit the remaining ones (the last group), and wait for all groups to finish. Then submit the repair writes and dev-replace writes. This should enlarge the queue depth. This would greatly improve the merge rate (thus read block size) and queue depth: Before (with regression, and cached extent/csum path): Device r/s rkB/s rrqm/s %rrqm r_await rareq-sz aqu-sz %util nvme0n1p3 20666.00 1318240.00 10.00 0.05 0.08 63.79 1.63 100.00 After (with all patches applied): nvme0n1p3 5165.00 2278304.00 30557.00 85.54 0.55 441.10 2.81 100.00 i.e. 1287 to 2224 MB/s. CC: stable@vger.kernel.org # 6.4+ Signed-off-by:
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Qu Wenruo authored
One of the bottleneck of the new scrub code is the extra csum tree search. The old code would only do the csum tree search for each scrub bio, which can be as large as 512KiB, thus they can afford to allocate a new path each time. But the new scrub code is doing csum tree search for each stripe, which is only 64KiB, this means we'd better re-use the same csum path during each search. This patch would introduce a per-sctx path for csum tree search, as we don't need to re-allocate the path every time we need to do a csum tree search. With this change we can further improve the queue depth and improve the scrub read performance: Before (with regression and cached extent tree path): Device r/s rkB/s rrqm/s %rrqm r_await rareq-sz aqu-sz %util nvme0n1p3 15875.00 1013328.00 12.00 0.08 0.08 63.83 1.35 100.00 After (with both cached extent/csum tree path): nvme0n1p3 17759.00 1133280.00 10.00 0.06 0.08 63.81 1.50 100.00 Fixes: e02ee89b ("btrfs: scrub: switch scrub_simple_mirror() to scrub_stripe infrastructure") CC: stable@vger.kernel.org # 6.4+ Signed-off-by:
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Qu Wenruo authored
Since commit e02ee89b ("btrfs: scrub: switch scrub_simple_mirror() to scrub_stripe infrastructure"), scrub no longer re-use the same path for extent tree search. This can lead to unnecessary extent tree search, especially for the new stripe based scrub, as we have way more stripes to prepare. This patch would re-introduce a shared path for extent tree search, and properly release it when the block group is scrubbed. This change alone can improve scrub performance slightly by reducing the time spend preparing the stripe thus improving the queue depth. Before (with regression): Device r/s rkB/s rrqm/s %rrqm r_await rareq-sz aqu-sz %util nvme0n1p3 15578.00 993616.00 5.00 0.03 0.09 63.78 1.32 100.00 After (with this patch): nvme0n1p3 15875.00 1013328.00 12.00 0.08 0.08 63.83 1.35 100.00 Fixes: e02ee89b ("btrfs: scrub: switch scrub_simple_mirror() to scrub_stripe infrastructure") CC: stable@vger.kernel.org # 6.4+ Signed-off-by:
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Lee Trager authored
btrfs supports creating nested subvolumes however snapshots are not recursive. When a snapshot is taken of a volume which contains a subvolume the subvolume is replaced with a stub subvolume which has the same name and uses inode number 2[1]. The stub subvolume kept the directory name but did not set the time or permissions of the stub subvolume. This resulted in all time information being the current time and ownership defaulting to root. When subvolumes and snapshots are created using unshare this results in a snapshot directory the user created but has no permissions for. Test case: [vmuser@archvm ~]# sudo -i [root@archvm ~]# mkdir -p /mnt/btrfs/test [root@archvm ~]# chown vmuser:users /mnt/btrfs/test/ [root@archvm ~]# exit logout [vmuser@archvm ~]$ cd /mnt/btrfs/test [vmuser@archvm test]$ unshare --user --keep-caps --map-auto --map-root-user [root@archvm test]# btrfs subvolume create subvolume Create subvolume './subvolume' [root@archvm test]# btrfs subvolume create subvolume/subsubvolume Create subvolume 'subvolume/subsubvolume' [root@archvm test]# btrfs subvolume snapshot subvolume snapshot Create a snapshot of 'subvolume' in './snapshot' [root@archvm test]# exit logout [vmuser@archvm test]$ tree -ug [vmuser users ] . ├── [vmuser users ] snapshot │ └── [vmuser users ] subsubvolume <-- Without patch perm is root:root └── [vmuser users ] subvolume └── [vmuser users ] subsubvolume 5 directories, 0 files [1] https://btrfs.readthedocs.io/en/latest/btrfs-subvolume.html#nested-subvolumesSigned-off-by:Lee Trager <lee@trager.us> Signed-off-by:
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Filipe Manana authored
At btrfs_readdir_delayed_dir_index(), called when reading a directory, we have this check for an empty list to return immediately, but it's not needed since list_for_each_entry_safe(), called immediately after, is prepared to deal with an empty list, it simply does nothing. So remove the empty list check. Besides shorter source code, it also slightly reduces the binary text size: Before this change: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1609408 167269 16864 1793541 1b5e05 fs/btrfs/btrfs.ko After this change: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1609392 167269 16864 1793525 1b5df5 fs/btrfs/btrfs.ko Signed-off-by:
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