FS/F2FS : Initial implementation
f2fs: fix to report newly allocate region as extent

Previous get_block in f2fs didn't report the newly allocated region which has
NEW_ADDR.
For reader, it should not report, but fiemap needs this.
So, this patch introduces two get_block sharing core function.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: recover fallocated data and its i_size together

This patch arranges the f2fs_locks to cover the fallocated data and its i_size.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: fix not to allocate unnecessary blocks during fallocate

This patch fixes the fallocate bug like below. (See xfstests/255)

In fallocate(fd, 0, 20480),
expand_inode_data processes
	for (index = pg_start; index <= pg_end; index++) {
		f2fs_reserve_block();
		...
	}

So, even though fallocate requests 20480, 5 blocks, f2fs allocates 6 blocks
including pg_end.
So, this patch adds one condition to avoid block allocation.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: remove unused variables in f2fs_sm_info

Remove unused variables in struct f2fs_sm_info.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: check lower bound nid value in check_nid_range

This patch add lower bound verification for nid in check_nid_range, so nids
reserved like 0, node, meta passed by caller could be checked there.

And then check_nid_range could be used in f2fs_nfs_get_inode for simplifying
code.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: fix error path in init_inode_metadata

If we fail in this path:
->init_inode_metadata
  ->make_empty_dir
    ->get_new_data_page
      ->grab_cache_page return -ENOMEM

We will bug on in error path of init_inode_metadata when call remove_inode_page
because i_block = 2 (one inode block will be released later & one dentry block).

We should release the dentry block in init_inode_metadata to avoid this BUG_ON,
and avoid leak of dentry block resource, because we never have second chance to
release that block in ->evict_inode as in upper error path we make this inode
'bad'.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: release new entry page correctly in error path of f2fs_rename

This patch correct releasing code of new_page to avoid BUG_ON in error patch of
f2fs_rename.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: do checkpoint for the renamed inode

If an inode is renamed, it should be registered as file_lost_pino to conduct
checkpoint at f2fs_sync_file.
Otherwise, the inode cannot be recovered due to no dent_mark in the following
scenario.

Note that, this scenario is from xfstests/322.

1. create "a"
2. fsync "a"
3. rename "a" to "b"
4. fsync "b"
5. Sudden power-cut

After recovery is done, "b" should be seen.
However, the result shows "a", since the recovery procedure does not enter
recover_dentry due to no dent_mark.

The reason is like below.
- The nid of "a" is checkpointed during #2, f2fs_sync_file.
- The inode page for "b" produced by #3 is written without dent_mark by
sync_node_pages.

So, this patch fixes this bug by assinging file_lost_pino to the "a"'s inode.
If the pino is lost, f2fs_sync_file conducts checkpoint, and then recovers
the latest pino and its dentry information for further recovery.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: check bdi->dirty_exceeded when trying to skip data writes

If we don't check the current backing device status, balance_dirty_pages can
fall into infinite pausing routine.

This can be occurred when a lot of directories make a small number of dirty
dentry pages including files.

Reported-by: Brian Chadwick <brianchad@westnet.com.au>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: avoid to access NULL pointer in issue_flush_thread

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=75861

Denis 2014-05-10 11:28:59 UTC reported:
"F2FS-fs (mmcblk0p28): mounting..
 Unable to handle kernel NULL pointer dereference at virtual address 00000018
 ...
 [<c0a2f678>] (_raw_spin_lock+0x3c/0x70) from [<c03a0330>] (issue_flush_thread+0x50/0x17c)
 [<c03a0330>] (issue_flush_thread+0x50/0x17c) from [<c01b4064>] (kthread+0x98/0xa4)
 [<c01b4064>] (kthread+0x98/0xa4) from [<c0108060>] (kernel_thread_exit+0x0/0x8)"

This patch assign cmd_control_info in sm_info before issue_flush_thread is being
created, so this make sure that issue flush thread will have no chance to access
invalid info in fcc.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: avoid unneeded SetPageUptodate in f2fs_write_end

We have already set page update in ->write_begin, so we should remove redundant
SetPageUptodate in ->write_end.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: avoid to truncate non-updated page partially

After we call find_data_page in truncate_partial_data_page, we could not
guarantee this page is updated or not as error may occurred in lower layer.

We'd better check status of the page to avoid this no updated page be
writebacked to device.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: introduce f2fs_do_tmpfile for code consistency

This patch adds f2fs_do_tmpfile to eliminate the redundant init_inode_metadata
flow.
Throught this, we can provide the consistent lock usage, e.g., fi->i_sem,  and
this will enable better debugging stuffs.

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

Conflicts:
	fs/f2fs/namei.c
f2fs: refactor flush_nat_entries codes for reducing NAT writes

Although building NAT journal in cursum reduce the read/write work for NAT
block, but previous design leave us lower performance when write checkpoint
frequently for these cases:
1. if journal in cursum has already full, it's a bit of waste that we flush all
   nat entries to page for persistence, but not to cache any entries.
2. if journal in cursum is not full, we fill nat entries to journal util
   journal is full, then flush the left dirty entries to disk without merge
   journaled entries, so these journaled entries may be flushed to disk at next
   checkpoint but lost chance to flushed last time.

In this patch we merge dirty entries located in same NAT block to nat entry set,
and linked all set to list, sorted ascending order by entries' count of set.
Later we flush entries in sparse set into journal as many as we can, and then
flush merged entries to disk. In this way we can not only gain in performance,
but also save lifetime of flash device.

In my testing environment, it shows this patch can help to reduce NAT block
writes obviously. In hard disk test case: cost time of fsstress is stablely
reduced by about 5%.

1. virtual machine + hard disk:
fsstress -p 20 -n 200 -l 5
		node num	cp count	nodes/cp
based		4599.6		1803.0		2.551
patched		2714.6		1829.6		1.483

2. virtual machine + 32g micro SD card:
fsstress -p 20 -n 200 -l 1 -w -f chown=0 -f creat=4 -f dwrite=0
-f fdatasync=4 -f fsync=4 -f link=0 -f mkdir=4 -f mknod=4 -f rename=5
-f rmdir=5 -f symlink=0 -f truncate=4 -f unlink=5 -f write=0 -S

		node num	cp count	nodes/cp
based		84.5		43.7		1.933
patched		49.2		40.0		1.23

Our latency of merging op shows not bad when handling extreme case like:
merging a great number of dirty nats:
latency(ns)	dirty nat count
3089219		24922
5129423		27422
4000250		24523

change log from v1:
 o fix wrong logic in add_nat_entry when grab a new nat entry set.
 o swith to create slab cache in create_node_manager_caches.
 o use GFP_ATOMIC instead of GFP_NOFS to avoid potential long latency.

change log from v2:
 o make comment position more appropriate suggested by Jaegeuk Kim.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: replace count*size kzalloc by kcalloc

kcalloc manages count*sizeof overflow.

Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Cc: linux-f2fs-devel@lists.sourceforge.net
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: check name_len of dir entry to prevent from deadloop

We assume that modification of some special application could result in zeroed
name_len, or it is consciously made by somebody. We will deadloop in
find_in_block when name_len of dir entry is zero.

This patch is added for preventing deadloop in above scenario.

change log from v1:
 o use f2fs_bug_on rather than break out from searching dir entry suggested by
Jaegeuk Kim.

Jaegeuk describe:
"Well, IMO, it would be good to add f2fs_bug_on() here with a specific comment.
In the current phase of f2fs, it is more important to investigate the file
system bugs, rather than workarounds for any corrupted images.
And, definitely it needs to stop the kernel if any corrupted image was mounted,
so that we can figure out where the bugs are occurred."

Suggested-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: reduce region of f2fs_lock_op covered for better concurrency

In our rename process, region of f2fs_lock_op covered is too big as some of the
code like f2fs_empty_dir/f2fs_find_entry are not needed to protect by this lock.

So in the extreme case like doing checkpoint when we rename old inode to exist
inode in a large directory could cause lower concurrency.

Let's reduce the region of f2fs_lock_op to fix this.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: remove the unused stat_lock

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: clean up an unused parameter and assignment

This patch cleans up simple unnecessary codes.

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