From 64560e780e907dbd185ebd2de9192c2c80135ee0 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Tue, 11 Feb 2025 14:36:57 +0800 Subject: [PATCH] BACKPORT: FROMGIT: f2fs: fix to avoid panic once fallocation fails for pinfile syzbot reports a f2fs bug as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2746! CPU: 0 UID: 0 PID: 5323 Comm: syz.0.0 Not tainted 6.13.0-rc2-syzkaller-00018-g7cb1b4663150 #0 RIP: 0010:get_new_segment fs/f2fs/segment.c:2746 [inline] RIP: 0010:new_curseg+0x1f52/0x1f70 fs/f2fs/segment.c:2876 Call Trace: __allocate_new_segment+0x1ce/0x940 fs/f2fs/segment.c:3210 f2fs_allocate_new_section fs/f2fs/segment.c:3224 [inline] f2fs_allocate_pinning_section+0xfa/0x4e0 fs/f2fs/segment.c:3238 f2fs_expand_inode_data+0x696/0xca0 fs/f2fs/file.c:1830 f2fs_fallocate+0x537/0xa10 fs/f2fs/file.c:1940 vfs_fallocate+0x569/0x6e0 fs/open.c:327 do_vfs_ioctl+0x258c/0x2e40 fs/ioctl.c:885 __do_sys_ioctl fs/ioctl.c:904 [inline] __se_sys_ioctl+0x80/0x170 fs/ioctl.c:892 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 Concurrent pinfile allocation may run out of free section, result in panic in get_new_segment(), let's expand pin_sem lock coverage to include f2fs_gc(), so that we can make sure to reclaim enough free space for following allocation. In addition, do below changes to enhance error path handling: - call f2fs_bug_on() only in non-pinfile allocation path in get_new_segment(). - call reset_curseg_fields() to reset all fields of curseg in new_curseg() Fixes: f5a53edcf01e ("f2fs: support aligned pinned file") Reported-by: syzbot+15669ec8c35ddf6c3d43@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/675cd64e.050a0220.37aaf.00bb.GAE@google.com Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Bug: 399583169 (cherry picked from commit 48ea8b200414ac69ea96f4c231f5c7ef1fbeffef https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git dev) Link: https://lore.kernel.org/linux-f2fs-devel/20250211063657.405289-1-chao@kernel.org/ [Jaegeuk: apply the pin_sem control only.] Change-Id: Ie98beaed369e87f1fd14d10fb0e94b706f0bdd23 --- fs/f2fs/file.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index e8ba98a18598..f6b133f373db 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1808,16 +1808,18 @@ static int f2fs_expand_inode_data(struct inode *inode, loff_t offset, map.m_len = sec_blks; next_alloc: + f2fs_down_write(&sbi->pin_sem); + if (has_not_enough_free_secs(sbi, 0, GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) { f2fs_down_write(&sbi->gc_lock); err = f2fs_gc(sbi, &gc_control); - if (err && err != -ENODATA) + if (err && err != -ENODATA) { + f2fs_up_write(&sbi->pin_sem); goto out_err; + } } - f2fs_down_write(&sbi->pin_sem); - f2fs_lock_op(sbi); f2fs_allocate_new_section(sbi, CURSEG_COLD_DATA_PINNED, false); f2fs_unlock_op(sbi);