From: Filipe Manana Date: Wed, 24 Sep 2025 15:10:38 +0000 (+0100) Subject: btrfs: fix clearing of BTRFS_FS_RELOC_RUNNING if relocation already running X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7e5a5983edda664e8e4bb20af17b80f5135c655c;p=users%2Fhch%2Fmisc.git btrfs: fix clearing of BTRFS_FS_RELOC_RUNNING if relocation already running When starting relocation, at reloc_chunk_start(), if we happen to find the flag BTRFS_FS_RELOC_RUNNING is already set we return an error (-EINPROGRESS) to the callers, however the callers call reloc_chunk_end() which will clear the flag BTRFS_FS_RELOC_RUNNING, which is wrong since relocation was started by another task and still running. Finding the BTRFS_FS_RELOC_RUNNING flag already set is an unexpected scenario, but still our current behaviour is not correct. Fix this by never calling reloc_chunk_end() if reloc_chunk_start() has returned an error, which is what logically makes sense, since the general widespread pattern is to have end functions called only if the counterpart start functions succeeded. This requires changing reloc_chunk_start() to clear BTRFS_FS_RELOC_RUNNING if there's a pending cancel request. Fixes: 907d2710d727 ("btrfs: add cancellable chunk relocation support") CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Boris Burkov Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 8dd8de6b9fb8..0765e06d00b8 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -3780,6 +3780,7 @@ out: /* * Mark start of chunk relocation that is cancellable. Check if the cancellation * has been requested meanwhile and don't start in that case. + * NOTE: if this returns an error, reloc_chunk_end() must not be called. * * Return: * 0 success @@ -3796,10 +3797,8 @@ static int reloc_chunk_start(struct btrfs_fs_info *fs_info) if (atomic_read(&fs_info->reloc_cancel_req) > 0) { btrfs_info(fs_info, "chunk relocation canceled on start"); - /* - * On cancel, clear all requests but let the caller mark - * the end after cleanup operations. - */ + /* On cancel, clear all requests. */ + clear_and_wake_up_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags); atomic_set(&fs_info->reloc_cancel_req, 0); return -ECANCELED; } @@ -3808,9 +3807,11 @@ static int reloc_chunk_start(struct btrfs_fs_info *fs_info) /* * Mark end of chunk relocation that is cancellable and wake any waiters. + * NOTE: call only if a previous call to reloc_chunk_start() succeeded. */ static void reloc_chunk_end(struct btrfs_fs_info *fs_info) { + ASSERT(test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)); /* Requested after start, clear bit first so any waiters can continue */ if (atomic_read(&fs_info->reloc_cancel_req) > 0) btrfs_info(fs_info, "chunk relocation canceled during operation"); @@ -4023,9 +4024,9 @@ out: if (err && rw) btrfs_dec_block_group_ro(rc->block_group); iput(rc->data_inode); + reloc_chunk_end(fs_info); out_put_bg: btrfs_put_block_group(bg); - reloc_chunk_end(fs_info); free_reloc_control(rc); return err; } @@ -4208,8 +4209,8 @@ out_clean: ret = ret2; out_unset: unset_reloc_control(rc); -out_end: reloc_chunk_end(fs_info); +out_end: free_reloc_control(rc); out: free_reloc_roots(&reloc_roots);