LKP reported -36.3% regression of fsmark.files_per_sec due to this patch.
I've confirmed that fxmark [1] has also slight regression for DWAL.

[1] https://github.com/sslab-gatech/fxmark

This reverts commit ec795418.

Datas in file can be operated by GC and DIO simultaneously, so we will
face race case as below:

For write case:
Thread A				Thread B
- generic_file_direct_write
 - invalidate_inode_pages2_range
 - f2fs_direct_IO
  - do_blockdev_direct_IO
   - do_direct_IO
    - get_more_blocks
					- f2fs_gc
					 - do_garbage_collect
					  - gc_data_segment
					   - move_data_page
					    - do_write_data_page
					    migrate data block to new block address
   - dio_bio_submit
   update user data to old block address

For read case:
Thread A                                Thread B
- generic_file_direct_write
 - invalidate_inode_pages2_range
 - f2fs_direct_IO
  - do_blockdev_direct_IO
   - do_direct_IO
    - get_more_blocks
					- f2fs_balance_fs
					 - f2fs_gc
					  - do_garbage_collect
					   - gc_data_segment
					    - move_data_page
					     - do_write_data_page
					     migrate data block to new block address
					  - write_checkpoint
					   - do_checkpoint
					    - clear_prefree_segments
					     - f2fs_issue_discard
                                             discard old block adress
   - dio_bio_submit
   update user buffer from obsolete block address

In order to fix this, for one file, we should let DIO and GC getting exclusion
against with each other.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Let's check inode's dirtiness before calling mark_inode_dirty.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

As manual described, f_bfree indicates total free blocks in fs, in f2fs, it
includes two parts: visible free blocks and over-provision blocks. This
patch corrrects the calculation.

fsblkcnt_t   f_bfree;   /* free blocks in fs */
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch replaces rw_semaphore with percpu_rw_semaphore for:
sbi->cp_rwsem
nm_i->nat_tree_lock
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds 'nodiscard' mount option.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

If mkfs.f2fs gives a feature flag for host-managed SMR, we can set mode=lfs
by default.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Let's store orphan inode pages right away.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This mount option is to enable original log-structured filesystem forcefully.
So, there should be no random writes for main area.

Especially, this supports host-managed SMR device.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

There is a data race between allocate_data_block() and f2fs_sbumit_page_mbio(),
which incur unnecessary reversed bio submission.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

We don't need lock parameter, which is always true.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

The number should be covered by spin_lock. Otherwise we can see wrong count
in f2fs_stat.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch removes writepages lock.
We can improve multi-threading performance.

tiobench, 32 threads, 4KB write per fsync on SSD
Before: 25.88 MB/s
After: 28.03 MB/s
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch sets flush_merge by default.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds lazytime support.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

If roll-forward recovery can recover i_size, we don't need to update inode's
metadata during fsync.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch registers all the inodes which have dirty metadata to sync when
checkpoint is doing.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch introduces f2fs_i_size_write() to call mark_inode_dirty_sync() with
i_size_write().
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch refactors to use inode pointer for set_inode_flag and
clear_inode_flag.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

it's not needed for file_operations of inodes located on fs defined
in the hosting module and for file_operations that go into procfs.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

init_f2fs_fs does:
    1) f2fs_build_trace_ios
    2) init_inodecache
    3) create_node_manager_caches
    4) create_segment_manager_caches
    5) create_checkpoint_caches
    6) create_extent_cache
    7) kset_create_and_add
    8) kobject_init_and_add
    9) register_shrinker
    10) register_filesystem
    11) f2fs_create_root_stats
    12) proc_mkdir

exit_f2fs_fs should do cleanup in the reverse order
to make the code more clear.
Signed-off-by: NTiezhu Yang <kernelpatch@126.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch uses percpu_counter to avoid stat_lock.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch uses percpu_count for sbi->alloc_valid_block_count.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds percpu_counter for # of dirty pages in inode.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch substitutes percpu_counter for atomic_counter when counting
various types of pages.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This can reduce page counting overhead.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch introduces a new struct f2fs_fault_info and a global f2fs_fault
to save fault injection status. Fault injection entries are created in
/sys/fs/f2fs/fault_injection/ during initializing f2fs module.
Signed-off-by: NSheng Yong <shengyong1@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Signed-off-by: NSheng Yong <shengyong1@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch allows fscrypto to handle a second key prefix given by filesystem.
The main reason is to provide backward compatibility, since previously f2fs
used "f2fs:" as a crypto prefix instead of "fscrypt:".
Later, ext4 should also provide key_prefix() to give "ext4:".

One concern decribed by Ted would be kinda double check overhead of prefixes.
In x86, for example, validate_user_key consumes 8 ms after boot-up, which turns
out derive_key_aes() consumed most of the time to load specific crypto module.
After such the cold miss, it shows almost zero latencies, which treats as a
negligible overhead.
Note that request_key() detects wrong prefix in prior to derive_key_aes() even.

Cc: Ted Tso <tytso@mit.edu>
Cc: stable@vger.kernel.org # v4.6
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

When unmounting filesystem, we should release all the ino entries.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch injects ENOSPC failures.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds page allocation failures.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch injects kmalloc failure given a fault injection rate.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds a mount option to select fault ratio.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds a new proc entry to show segment information in more detail.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This adds macros to be used multiple proc entries.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

When user remounts f2fs as read-only, we can mark the checkpoint as umount.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Once detecting something to recover, f2fs should stop mounting, given norecovery
and rw mount options.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds a sbi flag, SBI_NEED_SB_WRITE, which indicates it needs to
recover superblock when (re)mounting as RW. This is set only when f2fs is
mounted as RO.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>