Commit 48ea8b20 authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

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:
 <TASK>
 __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: f5a53edc ("f2fs: support aligned pinned file")
Reported-by: default avatar <syzbot+15669ec8c35ddf6c3d43@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/linux-f2fs-devel/675cd64e.050a0220.37aaf.00bb.GAE@google.com


Signed-off-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 5f95c181

fs/f2fs/file.c

+5 −3
Original line number Diff line number Diff line
@@ -1834,17 +1834,19 @@ 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, f2fs_sb_has_blkzoned(sbi) ?

			ZONED_PIN_SEC_REQUIRED_COUNT :

			GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {

			f2fs_down_write(&sbi->gc_lock);

			stat_inc_gc_call_count(sbi, FOREGROUND);

			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);

		}



		err = f2fs_allocate_pinning_section(sbi);

		if (err) {

fs/f2fs/segment.c

+10 −10
Original line number Diff line number Diff line
@@ -2806,7 +2806,7 @@ static int get_new_segment(struct f2fs_sb_info *sbi, 
							MAIN_SECS(sbi));

		if (secno >= MAIN_SECS(sbi)) {

			ret = -ENOSPC;

			f2fs_bug_on(sbi, 1);

			f2fs_bug_on(sbi, !pinning);

			goto out_unlock;

		}

	}
@@ -2848,7 +2848,7 @@ static int get_new_segment(struct f2fs_sb_info *sbi, 
out_unlock:

	spin_unlock(&free_i->segmap_lock);



	if (ret == -ENOSPC)

	if (ret == -ENOSPC && !pinning)

		f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_NO_SEGMENT);

	return ret;

}
@@ -2921,6 +2921,13 @@ static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type) 
	return curseg->segno;

}



static void reset_curseg_fields(struct curseg_info *curseg)

{

	curseg->inited = false;

	curseg->segno = NULL_SEGNO;

	curseg->next_segno = 0;

}



/*

 * Allocate a current working segment.

 * This function always allocates a free segment in LFS manner.
@@ -2939,7 +2946,7 @@ static int new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec) 
	ret = get_new_segment(sbi, &segno, new_sec, pinning);

	if (ret) {

		if (ret == -ENOSPC)

			curseg->segno = NULL_SEGNO;

			reset_curseg_fields(curseg);

		return ret;

	}
@@ -3710,13 +3717,6 @@ static void f2fs_randomize_chunk(struct f2fs_sb_info *sbi, 
		get_random_u32_inclusive(1, sbi->max_fragment_hole);

}



static void reset_curseg_fields(struct curseg_info *curseg)

{

	curseg->inited = false;

	curseg->segno = NULL_SEGNO;

	curseg->next_segno = 0;

}



int f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,

		block_t old_blkaddr, block_t *new_blkaddr,

		struct f2fs_summary *sum, int type,