f2fs: fix to don't panic system for no free segment fault injection

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to don't panic system for no free segment fault injection

f2fs: fix to don't panic system for no free segment fault injection

syzbot reports a f2fs bug as below:

F2FS-fs (loop0): inject no free segment in get_new_segment of __allocate_new_segment+0x1ce/0x940 fs/f2fs/segment.c:3167 F2FS-fs (loop0): Stopped filesystem due to reason: 7 ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2748! CPU: 0 UID: 0 PID: 5109 Comm: syz-executor304 Not tainted 6.11.0-rc6-syzkaller-00363-g89f5e14d05b4 #0 RIP: 0010:get_new_segment fs/f2fs/segment.c:2748 [inline] RIP: 0010:new_curseg+0x1f61/0x1f70 fs/f2fs/segment.c:2836 Call Trace: __allocate_new_segment+0x1ce/0x940 fs/f2fs/segment.c:3167 f2fs_allocate_new_section fs/f2fs/segment.c:3181 [inline] f2fs_allocate_pinning_section+0xfa/0x4e0 fs/f2fs/segment.c:3195 f2fs_expand_inode_data+0x5d6/0xbb0 fs/f2fs/file.c:1799 f2fs_fallocate+0x448/0x960 fs/f2fs/file.c:1903 vfs_fallocate+0x553/0x6c0 fs/open.c:334 do_vfs_ioctl+0x2592/0x2e50 fs/ioctl.c:886 __do_sys_ioctl fs/ioctl.c:905 [inline] __se_sys_ioctl+0x81/0x170 fs/ioctl.c:893 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: 0010:get_new_segment fs/f2fs/segment.c:2748 [inline] RIP: 0010:new_curseg+0x1f61/0x1f70 fs/f2fs/segment.c:2836

The root cause is when we inject no free segment fault into f2fs, we should not panic system, fix it.