This patch adds issued read IO counts which is under block layer.

Chao modified a bit, since:

Below race can cause reversed reference on F2FS_RD_DATA, there is
the same issue in f2fs_submit_page_bio(), fix them by relocate
__submit_bio() and inc_page_count.

Thread A			Thread B
- f2fs_write_begin
 - f2fs_submit_page_read
 - __submit_bio
				- f2fs_read_end_io
				 - __read_end_io
				 - dec_page_count(, F2FS_RD_DATA)
 - inc_page_count(, F2FS_RD_DATA)

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Note that, it requires "f2fs: return correct errno in f2fs_gc".

This adds a lightweight non-persistent snapshotting scheme to f2fs.

To use, mount with the option checkpoint=disable, and to return to
normal operation, remount with checkpoint=enable. If the filesystem
is shut down before remounting with checkpoint=enable, it will revert
back to its apparent state when it was first mounted with
checkpoint=disable. This is useful for situations where you wish to be
able to roll back the state of the disk in case of some critical
failure.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
[Jaegeuk Kim: use SB_RDONLY instead of MS_RDONLY]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

This patch adds to account skip count of background GC, and show stat
info via 'status' debugfs entry.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

This patch supports to account meta IO, it enables to show write IO
from f2fs more comprehensively via 'status' debugfs entry.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Remove the verbose license text from f2fs files and replace them with
SPDX tags.  This does not change the license of any of the code.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

https://bugzilla.kernel.org/show_bug.cgi?id=200951

These is a NULL pointer dereference issue reported in bugzilla:

Hi,
in the setup there is a SATA SSD connected to a SATA-to-USB bridge.

The disc is "Samsung SSD 850 PRO 256G" which supports TRIM.
There are four partitions:
 sda1: FAT  /boot
 sda2: F2FS /
 sda3: F2FS /home
 sda4: F2FS

The bridge is ASMT1153e which uses the "uas" driver.
There is no TRIM pass-through, so, when mounting it reports:
 mounting with "discard" option, but the device does not support discard

The USB host is USB3.0 and UASP capable. It is the one on RK3399.

Given this everything works fine, except there is no TRIM support.

In order to enable TRIM a new UDEV rule is added [1]:
 /etc/udev/rules.d/10-sata-bridge-trim.rules:
 ACTION=="add|change", ATTRS{idVendor}=="174c", ATTRS{idProduct}=="55aa", SUBSYSTEM=="scsi_disk", ATTR{provisioning_mode}="unmap"
After reboot any F2FS write hangs forever and dmesg reports:
 Unable to handle kernel NULL pointer dereference

Also tested on a x86_64 system: works fine even with TRIM enabled.
 same disc
 same bridge
 different usb host controller
 different cpu architecture
 not root filesystem

Regards,
  Vicenç.

[1] Post #5 in https://bbs.archlinux.org/viewtopic.php?id=236280

 Unable to handle kernel NULL pointer dereference at virtual address 000000000000003e
 Mem abort info:
   ESR = 0x96000004
   Exception class = DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
 Data abort info:
   ISV = 0, ISS = 0x00000004
   CM = 0, WnR = 0
 user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000626e3122
 [000000000000003e] pgd=0000000000000000
 Internal error: Oops: 96000004 [#1] SMP
 Modules linked in: overlay snd_soc_hdmi_codec rc_cec dw_hdmi_i2s_audio dw_hdmi_cec snd_soc_simple_card snd_soc_simple_card_utils snd_soc_rockchip_i2s rockchip_rga snd_soc_rockchip_pcm rockchipdrm videobuf2_dma_sg v4l2_mem2mem rtc_rk808 videobuf2_memops analogix_dp videobuf2_v4l2 videobuf2_common dw_hdmi dw_wdt cec rc_core videodev drm_kms_helper media drm rockchip_thermal rockchip_saradc realtek drm_panel_orientation_quirks syscopyarea sysfillrect sysimgblt fb_sys_fops dwmac_rk stmmac_platform stmmac pwm_bl squashfs loop crypto_user gpio_keys hid_kensington
 CPU: 5 PID: 957 Comm: nvim Not tainted 4.19.0-rc1-1-ARCH #1
 Hardware name: Sapphire-RK3399 Board (DT)
 pstate: 00000005 (nzcv daif -PAN -UAO)
 pc : update_sit_entry+0x304/0x4b0
 lr : update_sit_entry+0x108/0x4b0
 sp : ffff00000ca13bd0
 x29: ffff00000ca13bd0 x28: 000000000000003e
 x27: 0000000000000020 x26: 0000000000080000
 x25: 0000000000000048 x24: ffff8000ebb85cf8
 x23: 0000000000000253 x22: 00000000ffffffff
 x21: 00000000000535f2 x20: 00000000ffffffdf
 x19: ffff8000eb9e6800 x18: ffff8000eb9e6be8
 x17: 0000000007ce6926 x16: 000000001c83ffa8
 x15: 0000000000000000 x14: ffff8000f602df90
 x13: 0000000000000006 x12: 0000000000000040
 x11: 0000000000000228 x10: 0000000000000000
 x9 : 0000000000000000 x8 : 0000000000000000
 x7 : 00000000000535f2 x6 : ffff8000ebff3440
 x5 : ffff8000ebff3440 x4 : ffff8000ebe3a6c8
 x3 : 00000000ffffffff x2 : 0000000000000020
 x1 : 0000000000000000 x0 : ffff8000eb9e5800
 Process nvim (pid: 957, stack limit = 0x0000000063a78320)
 Call trace:
  update_sit_entry+0x304/0x4b0
  f2fs_invalidate_blocks+0x98/0x140
  truncate_node+0x90/0x400
  f2fs_remove_inode_page+0xe8/0x340
  f2fs_evict_inode+0x2b0/0x408
  evict+0xe0/0x1e0
  iput+0x160/0x260
  do_unlinkat+0x214/0x298
  __arm64_sys_unlinkat+0x3c/0x68
  el0_svc_handler+0x94/0x118
  el0_svc+0x8/0xc
 Code: f9400800 b9488400 36080140 f9400f01 (387c4820)
 ---[ end trace a0f21a307118c477 ]---

The reason is it is possible to enable discard flag on block queue via
UDEV, but during mount, f2fs will initialize se->discard_map only if
this flag is set, once the flag is set after mount, f2fs may dereference
NULL pointer on se->discard_map.

So this patch does below changes to fix this issue:
- initialize and update se->discard_map all the time.
- don't clear DISCARD option if device has no QUEUE_FLAG_DISCARD flag
during mount.
- don't issue small discard on zoned block device.
- introduce some functions to enhance the readability.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Tested-by: Vicente Bergas <vicencb@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

This patch used f2fs_bitmap_size macro to calculate mem used by
free nid bitmap, and stat used mem including aligned part.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

f2fs doesn't allow abuse on atomic write class interface, so except
limiting in-mem pages' total memory usage capacity, we need to limit
atomic-write usage as well when filesystem is seriously fragmented,
otherwise we may run into infinite loop during foreground GC because
target blocks in victim segment are belong to atomic opened file for
long time.

Now, we will detect failure due to atomic write in foreground GC, if
the count exceeds threshold, we will drop all atomic written data in
cache, by this, I expect it can keep our system running safely to
prevent Dos attack.

In addition, his patch adds to show GC skip information in debugfs,
now it just shows count of skipped caused by atomic write.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

This patch introduces f2fs_kzalloc based on f2fs_kmalloc in order to
support error injection for kzalloc().

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

We forgot to remov memory footprint accounting of per-cpu type
variables, fix it.

Fixes: 35782b233f37 ("f2fs: remove percpu_count due to performance regression")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>