Under heavy fsstress, we may triggle panic while issuing discard,
because __check_sit_bitmap() detects that discard command may earse
valid data blocks, the root cause is as below race stack described,
since we removed lock when flushing quota data, quota data writeback
may race with write_checkpoint(), so that it causes inconsistency in
between cached discard entry and segment bitmap.

- f2fs_write_checkpoint
 - block_operations
  - set_sbi_flag(sbi, SBI_QUOTA_SKIP_FLUSH)
 - f2fs_flush_sit_entries
  - add_discard_addrs
   - __set_bit_le(i, (void *)de->discard_map);
						- f2fs_write_data_pages
						 - f2fs_write_single_data_page
						   : inode is quota one, cp_rwsem won't be locked
						  - f2fs_do_write_data_page
						   - f2fs_allocate_data_block
						    - f2fs_wait_discard_bio
						      : discard entry has not been added yet.
						    - update_sit_entry
 - f2fs_clear_prefree_segments
  - f2fs_issue_discard
  : add discard entry

In order to fix this, this patch uses node_write to serialize
f2fs_allocate_data_block and checkpoint.

Fixes: 435cbab95e39 ("f2fs: fix quota_sync failure due to f2fs_lock_op")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

We never use return value of __insert_discard_tree(), so remove it.

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

When a discard_cmd needs to be split due to dpolicy->max_requests, then
for the remaining length it will be either merged into another cmd or a
new discard_cmd will be created. In this case, there is double
accounting of dcc->undiscard_blks for the remaining len, due to which
it shows incorrect value in stats.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

In case a discard_cmd is split into several bios, the dc->error
must not be overwritten once an error is reported by a bio. Also,
move it under dc->lock.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

F2FS already has a default timeout of 5 secs for discards that
can be issued during umount, but it can take more than the 5 sec
timeout if the underlying UFS device queue is already full and there
are no more available free tags to be used. Fix this by submitting a
small batch of discard requests so that it won't cause the device
queue to be full at any time and thus doesn't incur its wait time
in the umount context.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

While checking discard timeout, we use specified type
UMOUNT_DISCARD_TIMEOUT, so just replace doplicy.timeout with
it, and switch doplicy.timeout to bool type.

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

Data flush can generate heavy IO and cause long latency during
flush, so it's not appropriate to trigger it in foreground
operation.

And also, we may face below potential deadlock during data flush:
- f2fs_write_multi_pages
 - f2fs_write_raw_pages
  - f2fs_write_single_data_page
   - f2fs_balance_fs
    - f2fs_balance_fs_bg
     - f2fs_sync_dirty_inodes
      - filemap_fdatawrite   -- stuck on flush same cluster

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

In order to avoid polluting global slab cache namespace.

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

As Geert Uytterhoeven reported:

for parameter HZ/50 in congestion_wait(BLK_RW_ASYNC, HZ/50);

On some platforms, HZ can be less than 50, then unexpected 0 timeout
jiffies will be set in congestion_wait().

This patch introduces a macro DEFAULT_IO_TIMEOUT to wrap a determinate
value with msecs_to_jiffies(20) to instead HZ/50 to avoid such issue.

Quoted from Geert Uytterhoeven:

"A timeout of HZ means 1 second.
HZ/50 means 20 ms, but has the risk of being zero, if HZ < 50.

If you want to use a timeout of 20 ms, you best use msecs_to_jiffies(20),
as that takes care of the special cases, and never returns 0."

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

This patch removes F2FS_MOUNT_ADAPTIVE and F2FS_MOUNT_LFS mount options,
and add F2FS_OPTION.fs_mode with below two status to indicate filesystem
mode.

enum {
	FS_MODE_ADAPTIVE,	/* use both lfs/ssr allocation */
	FS_MODE_LFS,		/* use lfs allocation only */
};

It can enhance code readability and fs mode's scalability.

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