when get fiemap starting from MAX_LFS_FILESIZE, (maxbytes - *len) < start will always true , then *len set zero. because of start offset is byhond file size, for erofs filesystem it will always return iomap.length with zero,iomap iterate will be infinite loop. In order to avoid this situation, it is better to calculate the actual mapping length at first. If the len is 0, there is no need to continue the operation. ------------[ cut here ]------------ WARNING: CPU: 7 PID: 905 at fs/iomap/iter.c:35 iomap_iter+0x97f/0xc70 Modules linked in: xfs erofs CPU: 7 PID: 905 Comm: iomap Tainted: G W 5.17.0-rc8 #27 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:iomap_iter+0x97f/0xc70 Code: 85 a1 fc ff ff e8 71 be 9c ff 0f 1f 44 00 00 e9 92 fc ff ff e8 62 be 9c ff 0f 0b b8 fb ff ff ff e9 fc f8 ff ff e8 51 be 9c ff <0f> 0b e9 2b fc ff ff e8 45 be 9c ff 0f 0b e9 e1 fb ff ff e8 39 be RSP: 0018:ffff888060a37ab0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff888060a37bb0 RCX: 0000000000000000 RDX: ffff88807e19a900 RSI: ffffffff81a7da7f RDI: ffff888060a37be0 RBP: 7fffffffffffffff R08: 0000000000000000 R09: ffff888060a37c20 R10: ffff888060a37c67 R11: ffffed100c146f8c R12: 7fffffffffffffff R13: 0000000000000000 R14: ffff888060a37bd8 R15: ffff888060a37c20 FS: 00007fd3cca01540(0000) GS:ffff888108780000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020010820 CR3: 0000000054b92000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> iomap_fiemap+0x1c9/0x2f0 erofs_fiemap+0x64/0x90 [erofs] do_vfs_ioctl+0x40d/0x12e0 __x64_sys_ioctl+0xaa/0x1c0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae </TASK> ---[ end trace 0000000000000000 ]--- watchdog: BUG: soft lockup - CPU#7 stuck for 26s! [iomap:905] Reported-by: Hulk Robot <hulkci@xxxxxxxxxx> Signed-off-by: Guo Xuenan <guoxuenan@xxxxxxxxxx> --- fs/ioctl.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/ioctl.c b/fs/ioctl.c index 1ed097e94af2..7f70e90766ed 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -171,8 +171,6 @@ int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo, u32 incompat_flags; int ret = 0; - if (*len == 0) - return -EINVAL; if (start > maxbytes) return -EFBIG; @@ -182,6 +180,9 @@ int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo, if (*len > maxbytes || (maxbytes - *len) < start) *len = maxbytes - start; + if (*len == 0) + return -EINVAL; + supported_flags |= FIEMAP_FLAG_SYNC; supported_flags &= FIEMAP_FLAGS_COMPAT; incompat_flags = fieinfo->fi_flags & ~supported_flags; -- 2.22.0
