kernel/linux.git/fs/btrfs, branch v6.10.6

btrfs: fix double inode unlock for direct IO sync writes

2024-08-14T13:34:38+00:00

commit e0391e92f9ab4fb3dbdeb139c967dcfa7ac4b115 upstream. If we do a direct IO sync write, at btrfs_sync_file(), and we need to skip inode logging or we get an error starting a transaction or an error when flushing delalloc, we end up unlocking the inode when we shouldn't under the 'out_release_extents' label, and then unlock it again at btrfs_direct_write(). Fix that by checking if we have to skip inode unlocking under that label. Reported-by: syzbot+7dbbb74af6291b5a5a8b@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/000000000000dfd631061eaeb4bc@google.com/ Fixes: 939b656bc8ab ("btrfs: fix corruption after buffer fault in during direct IO append write") Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

btrfs: fix corruption after buffer fault in during direct IO append write

2024-08-14T13:34:37+00:00

commit 939b656bc8ab203fdbde26ccac22bcb7f0985be5 upstream. During an append (O_APPEND write flag) direct IO write if the input buffer was not previously faulted in, we can corrupt the file in a way that the final size is unexpected and it includes an unexpected hole. The problem happens like this: 1) We have an empty file, with size 0, for example; 2) We do an O_APPEND direct IO with a length of 4096 bytes and the input buffer is not currently faulted in; 3) We enter btrfs_direct_write(), lock the inode and call generic_write_checks(), which calls generic_write_checks_count(), and that function sets the iocb position to 0 with the following code: if (iocb->ki_flags & IOCB_APPEND) iocb->ki_pos = i_size_read(inode); 4) We call btrfs_dio_write() and enter into iomap, which will end up calling btrfs_dio_iomap_begin() and that calls btrfs_get_blocks_direct_write(), where we update the i_size of the inode to 4096 bytes; 5) After btrfs_dio_iomap_begin() returns, iomap will attempt to access the page of the write input buffer (at iomap_dio_bio_iter(), with a call to bio_iov_iter_get_pages()) and fail with -EFAULT, which gets returned to btrfs at btrfs_direct_write() via btrfs_dio_write(); 6) At btrfs_direct_write() we get the -EFAULT error, unlock the inode, fault in the write buffer and then goto to the label 'relock'; 7) We lock again the inode, do all the necessary checks again and call again generic_write_checks(), which calls generic_write_checks_count() again, and there we set the iocb's position to 4K, which is the current i_size of the inode, with the following code pointed above: if (iocb->ki_flags & IOCB_APPEND) iocb->ki_pos = i_size_read(inode); 8) Then we go again to btrfs_dio_write() and enter iomap and the write succeeds, but it wrote to the file range [4K, 8K), leaving a hole in the [0, 4K) range and an i_size of 8K, which goes against the expectations of having the data written to the range [0, 4K) and get an i_size of 4K. Fix this by not unlocking the inode before faulting in the input buffer, in case we get -EFAULT or an incomplete write, and not jumping to the 'relock' label after faulting in the buffer - instead jump to a location immediately before calling iomap, skipping all the write checks and relocking. This solves this problem and it's fine even in case the input buffer is memory mapped to the same file range, since only holding the range locked in the inode's io tree can cause a deadlock, it's safe to keep the inode lock (VFS lock), as was fixed and described in commit 51bd9563b678 ("btrfs: fix deadlock due to page faults during direct IO reads and writes"). A sample reproducer provided by a reporter is the following: $ cat test.c #ifndef _GNU_SOURCE #define _GNU_SOURCE #endif #include #include #include #include #include int main(int argc, char *argv[]) { if (argc < 2) { fprintf(stderr, "Usage: %s \n", argv[0]); return 1; } int fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT | O_APPEND, 0644); if (fd < 0) { perror("creating test file"); return 1; } char *buf = mmap(NULL, 4096, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); ssize_t ret = write(fd, buf, 4096); if (ret < 0) { perror("pwritev2"); return 1; } struct stat stbuf; ret = fstat(fd, &stbuf); if (ret < 0) { perror("stat"); return 1; } printf("size: %llu\n", (unsigned long long)stbuf.st_size); return stbuf.st_size == 4096 ? 0 : 1; } A test case for fstests will be sent soon. Reported-by: Hanna Czenczek Link: https://lore.kernel.org/linux-btrfs/0b841d46-12fe-4e64-9abb-871d8d0de271@redhat.com/ Fixes: 8184620ae212 ("btrfs: fix lost file sync on direct IO write with nowait and dsync iocb") CC: stable@vger.kernel.org # 6.1+ Tested-by: Hanna Czenczek Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

btrfs: avoid using fixed char array size for tree names

2024-08-14T13:34:34+00:00

commit 12653ec36112ab55fa06c01db7c4432653d30a8d upstream. [BUG] There is a bug report that using the latest trunk GCC 15, btrfs would cause unterminated-string-initialization warning: linux-6.6/fs/btrfs/print-tree.c:29:49: error: initializer-string for array of ‘char’ is too long [-Werror=unterminated-string-initialization] 29 | { BTRFS_BLOCK_GROUP_TREE_OBJECTID, "BLOCK_GROUP_TREE" }, | ^~~~~~~~~~~~~~~~~~ [CAUSE] To print tree names we have an array of root_name_map structure, which uses "char name[16];" to store the name string of a tree. But the following trees have names exactly at 16 chars length: - "BLOCK_GROUP_TREE" - "RAID_STRIPE_TREE" This means we will have no space for the terminating '\0', and can lead to unexpected access when printing the name. [FIX] Instead of "char name[16];" use "const char *" instead. Since the name strings are all read-only data, and are all NULL terminated by default, there is not much need to bother the length at all. Reported-by: Sam James Reported-by: Alejandro Colomar Fixes: edde81f1abf29 ("btrfs: add raid stripe tree pretty printer") Fixes: 9c54e80ddc6bd ("btrfs: add code to support the block group root") CC: stable@vger.kernel.org # 6.1+ Suggested-by: Alejandro Colomar Reviewed-by: Johannes Thumshirn Reviewed-by: Alejandro Colomar Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

btrfs: fix bitmap leak when loading free space cache on duplicate entry

2024-08-14T13:34:12+00:00

[ Upstream commit 320d8dc612660da84c3b70a28658bb38069e5a9a ] If we failed to link a free space entry because there's already a conflicting entry for the same offset, we free the free space entry but we don't free the associated bitmap that we had just allocated before. Fix that by freeing the bitmap before freeing the entry. Reviewed-by: Johannes Thumshirn Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: fix data race when accessing the last_trans field of a root

2024-08-14T13:34:11+00:00

[ Upstream commit ca84529a842f3a15a5f17beac6252aa11955923f ] KCSAN complains about a data race when accessing the last_trans field of a root: [ 199.553628] BUG: KCSAN: data-race in btrfs_record_root_in_trans [btrfs] / record_root_in_trans [btrfs] [ 199.555186] read to 0x000000008801e308 of 8 bytes by task 2812 on cpu 1: [ 199.555210] btrfs_record_root_in_trans+0x9a/0x128 [btrfs] [ 199.555999] start_transaction+0x154/0xcd8 [btrfs] [ 199.556780] btrfs_join_transaction+0x44/0x60 [btrfs] [ 199.557559] btrfs_dirty_inode+0x9c/0x140 [btrfs] [ 199.558339] btrfs_update_time+0x8c/0xb0 [btrfs] [ 199.559123] touch_atime+0x16c/0x1e0 [ 199.559151] pipe_read+0x6a8/0x7d0 [ 199.559179] vfs_read+0x466/0x498 [ 199.559204] ksys_read+0x108/0x150 [ 199.559230] __s390x_sys_read+0x68/0x88 [ 199.559257] do_syscall+0x1c6/0x210 [ 199.559286] __do_syscall+0xc8/0xf0 [ 199.559318] system_call+0x70/0x98 [ 199.559431] write to 0x000000008801e308 of 8 bytes by task 2808 on cpu 0: [ 199.559464] record_root_in_trans+0x196/0x228 [btrfs] [ 199.560236] btrfs_record_root_in_trans+0xfe/0x128 [btrfs] [ 199.561097] start_transaction+0x154/0xcd8 [btrfs] [ 199.561927] btrfs_join_transaction+0x44/0x60 [btrfs] [ 199.562700] btrfs_dirty_inode+0x9c/0x140 [btrfs] [ 199.563493] btrfs_update_time+0x8c/0xb0 [btrfs] [ 199.564277] file_update_time+0xb8/0xf0 [ 199.564301] pipe_write+0x8ac/0xab8 [ 199.564326] vfs_write+0x33c/0x588 [ 199.564349] ksys_write+0x108/0x150 [ 199.564372] __s390x_sys_write+0x68/0x88 [ 199.564397] do_syscall+0x1c6/0x210 [ 199.564424] __do_syscall+0xc8/0xf0 [ 199.564452] system_call+0x70/0x98 This is because we update and read last_trans concurrently without any type of synchronization. This should be generally harmless and in the worst case it can make us do extra locking (btrfs_record_root_in_trans()) trigger some warnings at ctree.c or do extra work during relocation - this would probably only happen in case of load or store tearing. So fix this by always reading and updating the field using READ_ONCE() and WRITE_ONCE(), this silences KCSAN and prevents load and store tearing. Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: reduce nesting for extent processing at btrfs_lookup_extent_info()

2024-08-14T13:34:11+00:00

[ Upstream commit 5c83b3beaee06aa88d4015408ac2d8bb35380b06 ] Instead of using an if-else statement when processing the extent item at btrfs_lookup_extent_info(), use a single if statement for the error case since it does a goto at the end and leave the success (expected) case following the if statement, reducing indentation and making the logic a bit easier to follow. Also make the if statement's condition as unlikely since it's not expected to ever happen, as it signals some corruption, making it clear and hint the compiler to generate more efficient code. Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: do not BUG_ON() when freeing tree block after error

2024-08-14T13:34:11+00:00

[ Upstream commit bb3868033a4cccff7be57e9145f2117cbdc91c11 ] When freeing a tree block, at btrfs_free_tree_block(), if we fail to create a delayed reference we don't deal with the error and just do a BUG_ON(). The error most likely to happen is -ENOMEM, and we have a comment mentioning that only -ENOMEM can happen, but that is not true, because in case qgroups are enabled any error returned from btrfs_qgroup_trace_extent_post() (can be -EUCLEAN or anything returned from btrfs_search_slot() for example) can be propagated back to btrfs_free_tree_block(). So stop doing a BUG_ON() and return the error to the callers and make them abort the transaction to prevent leaking space. Syzbot was triggering this, likely due to memory allocation failure injection. Reported-by: syzbot+a306f914b4d01b3958fe@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/000000000000fcba1e05e998263c@google.com/ Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: do not clear page dirty inside extent_write_locked_range()

2024-08-14T13:34:11+00:00

[ Upstream commit 97713b1a2ced1e4a2a6c40045903797ebd44d7e0 ] [BUG] For subpage + zoned case, the following workload can lead to rsv data leak at unmount time: # mkfs.btrfs -f -s 4k $dev # mount $dev $mnt # fsstress -w -n 8 -d $mnt -s 1709539240 0/0: fiemap - no filename 0/1: copyrange read - no filename 0/2: write - no filename 0/3: rename - no source filename 0/4: creat f0 x:0 0 0 0/4: creat add id=0,parent=-1 0/5: writev f0[259 1 0 0 0 0] [778052,113,965] 0 0/6: ioctl(FIEMAP) f0[259 1 0 0 224 887097] [1294220,2291618343991484791,0x10000] -1 0/7: dwrite - xfsctl(XFS_IOC_DIOINFO) f0[259 1 0 0 224 887097] return 25, fallback to stat() 0/7: dwrite f0[259 1 0 0 224 887097] [696320,102400] 0 # umount $mnt The dmesg includes the following rsv leak detection warning (all call trace skipped): ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8653 btrfs_destroy_inode+0x1e0/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8654 btrfs_destroy_inode+0x1a8/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8660 btrfs_destroy_inode+0x1a0/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): last unmount of filesystem 1b4abba9-de34-4f07-9e7f-157cf12a18d6 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): space_info DATA has 268218368 free, is not full BTRFS info (device sda): space_info total=268435456, used=204800, pinned=0, reserved=0, may_use=12288, readonly=0 zone_unusable=0 BTRFS info (device sda): global_block_rsv: size 0 reserved 0 BTRFS info (device sda): trans_block_rsv: size 0 reserved 0 BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): space_info METADATA has 267796480 free, is not full BTRFS info (device sda): space_info total=268435456, used=131072, pinned=0, reserved=0, may_use=262144, readonly=0 zone_unusable=245760 BTRFS info (device sda): global_block_rsv: size 0 reserved 0 BTRFS info (device sda): trans_block_rsv: size 0 reserved 0 BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0 Above $dev is a tcmu-runner emulated zoned HDD, which has a max zone append size of 64K, and the system has 64K page size. [CAUSE] I have added several trace_printk() to show the events (header skipped): > btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688 > btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288 > btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536 > btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864 The above lines show our buffered write has dirtied 3 pages of inode 259 of root 5: 704K 768K 832K 896K I |////I/////////////////I///////////| I 756K 868K |///| is the dirtied range using subpage bitmaps. and 'I' is the page boundary. Meanwhile all three pages (704K, 768K, 832K) have their PageDirty flag set. > btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400 Then direct IO write starts, since the range [680K, 780K) covers the beginning part of the above dirty range, we need to writeback the two pages at 704K and 768K. > cow_file_range: r/i=5/259 add ordered extent filepos=774144 len=65536 > extent_write_locked_range: r/i=5/259 locked page=720896 start=774144 len=65536 Now the above 2 lines show that we're writing back for dirty range [756K, 756K + 64K). We only writeback 64K because the zoned device has max zone append size as 64K. > extent_write_locked_range: r/i=5/259 clear dirty for page=786432 !!! The above line shows the root cause. !!! We're calling clear_page_dirty_for_io() inside extent_write_locked_range(), for the page 768K. This is because extent_write_locked_range() can go beyond the current locked page, here we hit the page at 768K and clear its page dirt. In fact this would lead to the desync between subpage dirty and page dirty flags. We have the page dirty flag cleared, but the subpage range [820K, 832K) is still dirty. After the writeback of range [756K, 820K), the dirty flags look like this, as page 768K no longer has dirty flag set. 704K 768K 832K 896K I I | I/////////////| I 820K 868K This means we will no longer writeback range [820K, 832K), thus the reserved data/metadata space would never be properly released. > extent_write_cache_pages: r/i=5/259 skip non-dirty folio=786432 Now even though we try to start writeback for page 768K, since the page is not dirty, we completely skip it at extent_write_cache_pages() time. > btrfs_direct_write: r/i=5/259 dio done filepos=696320 len=0 Now the direct IO finished. > cow_file_range: r/i=5/259 add ordered extent filepos=851968 len=36864 > extent_write_locked_range: r/i=5/259 locked page=851968 start=851968 len=36864 Now we writeback the remaining dirty range, which is [832K, 868K). Causing the range [820K, 832K) never to be submitted, thus leaking the reserved space. This bug only affects subpage and zoned case. For non-subpage and zoned case, we have exactly one sector for each page, thus no such partial dirty cases. For subpage and non-zoned case, we never go into run_delalloc_cow(), and normally all the dirty subpage ranges would be properly submitted inside __extent_writepage_io(). [FIX] Just do not clear the page dirty at all inside extent_write_locked_range(). As __extent_writepage_io() would do a more accurate, subpage compatible clear for page and subpage dirty flags anyway. Now the correct trace would look like this: > btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688 > btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288 > btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536 > btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864 The page dirty part is still the same 3 pages. > btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400 > cow_file_range: r/i=5/259 add ordered extent filepos=774144 len=65536 > extent_write_locked_range: r/i=5/259 locked page=720896 start=774144 len=65536 And the writeback for the first 64K is still correct. > cow_file_range: r/i=5/259 add ordered extent filepos=839680 len=49152 > extent_write_locked_range: r/i=5/259 locked page=786432 start=839680 len=49152 Now with the fix, we can properly writeback the range [820K, 832K), and properly release the reserved data/metadata space. Reviewed-by: Johannes Thumshirn Signed-off-by: Qu Wenruo Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: make cow_file_range_inline() honor locked_page on error

2024-08-11T10:57:58+00:00

commit 478574370bef7951fbd9ef5155537d6cbed49472 upstream. The btrfs buffered write path runs through __extent_writepage() which has some tricky return value handling for writepage_delalloc(). Specifically, when that returns 1, we exit, but for other return values we continue and end up calling btrfs_folio_end_all_writers(). If the folio has been unlocked (note that we check the PageLocked bit at the start of __extent_writepage()), this results in an assert panic like this one from syzbot: BTRFS: error (device loop0 state EAL) in free_log_tree:3267: errno=-5 IO failure BTRFS warning (device loop0 state EAL): Skipping commit of aborted transaction. BTRFS: error (device loop0 state EAL) in cleanup_transaction:2018: errno=-5 IO failure assertion failed: folio_test_locked(folio), in fs/btrfs/subpage.c:871 ------------[ cut here ]------------ kernel BUG at fs/btrfs/subpage.c:871! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 1 PID: 5090 Comm: syz-executor225 Not tainted 6.10.0-syzkaller-05505-gb1bc554e009e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 RIP: 0010:btrfs_folio_end_all_writers+0x55b/0x610 fs/btrfs/subpage.c:871 Code: e9 d3 fb ff ff e8 25 22 c2 fd 48 c7 c7 c0 3c 0e 8c 48 c7 c6 80 3d 0e 8c 48 c7 c2 60 3c 0e 8c b9 67 03 00 00 e8 66 47 ad 07 90 <0f> 0b e8 6e 45 b0 07 4c 89 ff be 08 00 00 00 e8 21 12 25 fe 4c 89 RSP: 0018:ffffc900033d72e0 EFLAGS: 00010246 RAX: 0000000000000045 RBX: 00fff0000000402c RCX: 663b7a08c50a0a00 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 RBP: ffffc900033d73b0 R08: ffffffff8176b98c R09: 1ffff9200067adfc R10: dffffc0000000000 R11: fffff5200067adfd R12: 0000000000000001 R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0001cbee80 FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5f076012f8 CR3: 000000000e134000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __extent_writepage fs/btrfs/extent_io.c:1597 [inline] extent_write_cache_pages fs/btrfs/extent_io.c:2251 [inline] btrfs_writepages+0x14d7/0x2760 fs/btrfs/extent_io.c:2373 do_writepages+0x359/0x870 mm/page-writeback.c:2656 filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:397 __filemap_fdatawrite_range mm/filemap.c:430 [inline] __filemap_fdatawrite mm/filemap.c:436 [inline] filemap_flush+0xdf/0x130 mm/filemap.c:463 btrfs_release_file+0x117/0x130 fs/btrfs/file.c:1547 __fput+0x24a/0x8a0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:222 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xa2f/0x27f0 kernel/exit.c:877 do_group_exit+0x207/0x2c0 kernel/exit.c:1026 __do_sys_exit_group kernel/exit.c:1037 [inline] __se_sys_exit_group kernel/exit.c:1035 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1035 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5f075b70c9 Code: Unable to access opcode bytes at 0x7f5f075b709f. I was hitting the same issue by doing hundreds of accelerated runs of generic/475, which also hits IO errors by design. I instrumented that reproducer with bpftrace and found that the undesirable folio_unlock was coming from the following callstack: folio_unlock+5 __process_pages_contig+475 cow_file_range_inline.constprop.0+230 cow_file_range+803 btrfs_run_delalloc_range+566 writepage_delalloc+332 __extent_writepage # inlined in my stacktrace, but I added it here extent_write_cache_pages+622 Looking at the bisected-to patch in the syzbot report, Josef realized that the logic of the cow_file_range_inline error path subtly changing. In the past, on error, it jumped to out_unlock in cow_file_range(), which honors the locked_page, so when we ultimately call folio_end_all_writers(), the folio of interest is still locked. After the change, we always unlocked ignoring the locked_page, on both success and error. On the success path, this all results in returning 1 to __extent_writepage(), which skips the folio_end_all_writers() call, which makes it OK to have unlocked. Fix the bug by wiring the locked_page into cow_file_range_inline() and only setting locked_page to NULL on success. Reported-by: syzbot+a14d8ac9af3a2a4fd0c8@syzkaller.appspotmail.com Fixes: 0586d0a89e77 ("btrfs: move extent bit and page cleanup into cow_file_range_inline") CC: stable@vger.kernel.org # 6.10+ Reviewed-by: Qu Wenruo Signed-off-by: Boris Burkov Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

btrfs: do not subtract delalloc from avail bytes

2024-08-11T10:57:57+00:00

commit d89c285d28491d8f10534c262ac9e6bdcbe1b4d2 upstream. The block group's avail bytes printed when dumping a space info subtract the delalloc_bytes. However, as shown in btrfs_add_reserved_bytes() and btrfs_free_reserved_bytes(), it is added or subtracted along with "reserved" for the delalloc case, which means the "delalloc_bytes" is a part of the "reserved" bytes. So, excluding it to calculate the avail space counts delalloc_bytes twice, which can lead to an invalid result. Fixes: e50b122b832b ("btrfs: print available space for a block group when dumping a space info") CC: stable@vger.kernel.org # 6.6+ Signed-off-by: Naohiro Aota Reviewed-by: Boris Burkov Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman