o Deadlock case #1

Thread 1:
- writeback_sb_inodes
 - do_writepages
  - f2fs_write_data_pages
   - write_cache_pages
    - f2fs_write_data_page
     - f2fs_balance_fs
      - wait mutex_lock(gc_mutex)

Thread 2:
- f2fs_balance_fs
 - mutex_lock(gc_mutex)
 - f2fs_gc
  - f2fs_iget
   - wait iget_locked(inode->i_lock)

Thread 3:
- do_unlinkat
 - iput
  - lock(inode->i_lock)
   - evict
    - inode_wait_for_writeback

o Deadlock case #2

Thread 1:
- __writeback_single_inode
 : set I_SYNC
  - do_writepages
   - f2fs_write_data_page
    - f2fs_balance_fs
     - f2fs_gc
      - iput
       - evict
        - inode_wait_for_writeback(I_SYNC)

In order to avoid this, even though iput is called with the zero-reference
count, we need to stop the eviction procedure if the inode is on writeback.
So this patch links f2fs_drop_inode which checks the I_SYNC flag.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

When testing f2fs on an SSD, I found some 128 page IOs followed by 1 page IO
were issued by f2fs_write_node_pages.
This means that there were some mishandling flows which degrades performance.

Previous f2fs_write_node_pages determines the number of pages to be written,
nr_to_write, as follows.

1. The bio_get_nr_vecs returns 129 pages.
2. The bio_alloc makes a room for 128 pages.
3. The initial 128 pages go into one bio.
4. The existing bio is submitted, and a new bio is prepared for the last 1 page.
5. Finally, sync_node_pages submits the last 1 page bio.

The problem is from the use of bio_get_nr_vecs, so this patch replace it
with max_hw_blocks using queue_max_sectors.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

try_to_free_nats() is usually called with parameter nr_shrink as
	"nm_i->nat_cnt - NM_WOUT_THRESHOLD"
by flush_nat_entries() during checkpointing process.

However, this is inconsistent with the actual threshold check as
	"if (nm_i->nat_cnt < 2 * NM_WOUT_THRESHOLD)"
, which will ignore the free_nats requests when
	NM_WOUT_THRESHOLD < nm_i->nat_cnt < 2 * NM_WOUT_THRESHOLD

So fix the threshold check condition.

Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

We call lock_page when we need to update a page after readpage.
Between grab and lock page, the page can be truncated by other thread.
So, we should check the page after lock_page whether it was truncated or not.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

In order to avoid build_free_nid lock contention, let's change the order of
function calls as follows.

At first, check whether there is enough free nids.
 - If available, just get a free nid with spin_lock without any overhead.
 - Otherwise, conduct build_free_nids.
  : scan nat pages, journal nat entries, and nat cache entries.

We should consider carefullly not to serve free nids intermediately made by
build_free_nids.
We can get stable free nids only after build_free_nids is done.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

This can help when debugging the free nid allocation flows.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

It is more obvious that add_free_nid checks whether the free nid is zero or not.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Adding REQ_META for all the metadata requests can help in improving the
FS performance, if the underlying device supports TAGGING.
So, when considering the submit_bio path for all the f2fs requests. We can
add REQ_META for all the META requests.
As a precursor to this change we considered the commit
4265900e

 'mmc: MMC-4.5 Data Tag Support'

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Previously, background GC submits many 4KB read requests to load victim blocks
and/or its (i)node blocks.

...
f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb61, blkaddr = 0x3b964ed
f2fs_gc : block_rq_complete: 8,16 R () 499854968 + 8 [0]
f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb6f, blkaddr = 0x3b964ee
f2fs_gc : block_rq_complete: 8,16 R () 499854976 + 8 [0]
f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb79, blkaddr = 0x3b964ef
f2fs_gc : block_rq_complete: 8,16 R () 499854984 + 8 [0]
...

However, by the fact that many IOs are sequential, we can give a chance to merge
the IOs by IO scheduler.
In order to do that, let's use blk_plug.

...
f2fs_gc : f2fs_iget: ino = 143
f2fs_gc : f2fs_readpage: ino = 143, page_index = 0x1c6, blkaddr = 0x2e6ee
f2fs_gc : f2fs_iget: ino = 143
f2fs_gc : f2fs_readpage: ino = 143, page_index = 0x1c7, blkaddr = 0x2e6ef
<idle> : block_rq_complete: 8,16 R () 1519616 + 8 [0]
<idle> : block_rq_complete: 8,16 R () 1519848 + 8 [0]
<idle> : block_rq_complete: 8,16 R () 1520432 + 96 [0]
<idle> : block_rq_complete: 8,16 R () 1520536 + 104 [0]
<idle> : block_rq_complete: 8,16 R () 1521008 + 112 [0]
<idle> : block_rq_complete: 8,16 R () 1521440 + 152 [0]
<idle> : block_rq_complete: 8,16 R () 1521688 + 144 [0]
<idle> : block_rq_complete: 8,16 R () 1522128 + 192 [0]
<idle> : block_rq_complete: 8,16 R () 1523256 + 328 [0]
...

Note that this issue should be addressed in checkpoint, and some readahead
flows too.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

If there is no victim segments selected by background GC, let's wait
a little bit longer time to collect dirty segments.
By default, let's give 5 minutes.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Add tracepoints to debug checkpoint request.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: change expressions]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Add tracepoints to debug the various page write operation
like data pages, meta pages.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: remove unnecessary tracepoints]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Add tracepoints to debug the block allocation & fallocate.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: enhance information]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Add tracepoints for tracing the garbage collector
threads in f2fs with status of collection & type.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: modify slightly to show information]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Add tracepoints for page i/o operations and block allocation
tracing during page read operation.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: combine and modify the tracepoint structures]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

add tracepoints for tracing the truncate operations
like truncate node/data blocks, f2fs_truncate etc.

Tracepoints are added at entry and exit of operation
to trace the success & failure of operation.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: combine and modify the tracepoint structures]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Add tracepoints in f2fs for tracing the syncing
operations like filesystem sync, file sync enter/exit.
It will helf to trace the code under debugging scenarios.

Also add tracepoints for tracing the various inode operations
like building inode, eviction of inode, link/unlike of
inodes.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: combine and modify the tracepoint structures]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

The code conditions put inside the function is_multimedia_file are
reverse to the name i.e, we need to negate the return to actually
check if the file is a multimedia file. So, change the code and usage
path to align both the name and comparision conditions.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Fix to return a negative error code from the error handling
case instead of 0, as returned elsewhere in this function.
Introduce by commit c0d39e(f2fs: fix return values from validate superblock)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Fix typo mistakes.
1. I think that it should be 'L' instead of 'V'.
2. and try to fix 'Front' instead of 'Frone'

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

In order to be aware of prefree and free sections during FG_GC, let's start with
write_checkpoint().

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

If (ofs % (NIDS_PER_BLOCK + 1) == 0), the node is an indirect node block.

Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

In the previous version, f2fs uses global locks according to the usage types,
such as directory operations, block allocation, block write, and so on.

Reference the following lock types in f2fs.h.
enum lock_type {
	RENAME,		/* for renaming operations */
	DENTRY_OPS,	/* for directory operations */
	DATA_WRITE,	/* for data write */
	DATA_NEW,	/* for data allocation */
	DATA_TRUNC,	/* for data truncate */
	NODE_NEW,	/* for node allocation */
	NODE_TRUNC,	/* for node truncate */
	NODE_WRITE,	/* for node write */
	NR_LOCK_TYPE,
};

In that case, we lose the performance under the multi-threading environment,
since every types of operations must be conducted one at a time.

In order to address the problem, let's share the locks globally with a mutex
array regardless of any types.
So, let users grab a mutex and perform their jobs in parallel as much as
possbile.

For this, I propose a new global lock scheme as follows.

0. Data structure
 - f2fs_sb_info -> mutex_lock[NR_GLOBAL_LOCKS]
 - f2fs_sb_info -> node_write

1. mutex_lock_op(sbi)
 - try to get an avaiable lock from the array.
 - returns the index of the gottern lock variable.

2. mutex_unlock_op(sbi, index of the lock)
 - unlock the given index of the lock.

3. mutex_lock_all(sbi)
 - grab all the locks in the array before the checkpoint.

4. mutex_unlock_all(sbi)
 - release all the locks in the array after checkpoint.

5. block_operations()
 - call mutex_lock_all()
 - sync_dirty_dir_inodes()
 - grab node_write
 - sync_node_pages()

Note that,
 the pairs of mutex_lock_op()/mutex_unlock_op() and
 mutex_lock_all()/mutex_unlock_all() should be used together.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Move the f2fs_balance_fs out of the truncate_hole function and only
perform that in punch_hole use case.  The commit:

  ed60b1644e7f7e5dd67d21caf7e4425dff05dad0

intended to do this but moved it into truncate_hole to cover more
cases.  However, a deadlock scenario is possible when deleting an inode
entry under specific conditions:

 f2fs_delete_entry()
     mutex_lock_op(sbi, DENTRY_OPS);
     truncate_hole()
         f2fs_balance_fs()
             mutex_lock(&sbi->gc_mutex);
             f2fs_gc()
                 write_checkpoint()
                     block_operations()
                         mutex_lock_op(sbi, DENTRY_OPS);

Lets move it into the punch_hole case to cover the original intent of
avoiding it during fallocate's expand_inode_data case.

Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
Signed-off-by: Jason Hrycay <jason.hrycay@motorola.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

This patch reduces redundant spin_lock operations in alloc_nid_failed().
The alloc_nid_failed() does not need to delete entry and add one again
by triggering spin_lock and spin_unlock redundantly.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

 o mkfs.f2fs supports no discard option.
 o fixed volume label size in 512 bytes.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Commit - fa9150a8 - replaces a call to generic_writepages() in
f2fs_write_data_pages() with write_cache_pages(), with a function pointer
argument pointing to routine: __f2fs_writepage.

  -> https://git.kernel.org/linus/fa9150a84ca333f68127097c4fa1eda4b3913a22



  This patch adds a NULL pointer check in f2fs_write_data_pages() to avoid
  a possible NULL pointer dereference, in case if - mapping->a_ops->writepage -
  is NULL.

Signed-off-by: P J P <ppandit@redhat.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Like below, there are 8 segment bitmaps for SSR victim candidates.

enum dirty_type {
	DIRTY_HOT_DATA,		/* dirty segments assigned as hot data logs */
	DIRTY_WARM_DATA,	/* dirty segments assigned as warm data logs */
	DIRTY_COLD_DATA,	/* dirty segments assigned as cold data logs */
	DIRTY_HOT_NODE,		/* dirty segments assigned as hot node logs */
	DIRTY_WARM_NODE,	/* dirty segments assigned as warm node logs */
	DIRTY_COLD_NODE,	/* dirty segments assigned as cold node logs */
	DIRTY,			/* to count # of dirty segments */
	PRE,			/* to count # of entirely obsolete segments */
	NR_DIRTY_TYPE
};

The upper 6 bitmaps indicates segments dirtied by active log areas respectively.
And, the DIRTY bitmap integrates all the 6 bitmaps.

For example,
 o DIRTY_HOT_DATA : 1010000
 o DIRTY_WARM_DATA: 0100000
 o DIRTY_COLD_DATA: 0001000
 o DIRTY_HOT_NODE : 0000010
 o DIRTY_WARM_NODE: 0000001
 o DIRTY_COLD_NODE: 0000000
In this case,
 o DIRTY          : 1111011,

 which means that we should guarantee the consistency between DIRTY and other
 bitmaps concreately.

However, the SSR mode selects victims freely from any log types, which can set
multiple bits across the various bitmap types.

So, this patch eliminates this inconsistency.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

In order to do GC more reliably, I'd like to lock the vicitm summary page
until its GC is completed, and also prevent any checkpoint process.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

This patch adds a new condition that allocates free segments in the current
active section even if SSR is needed.
Otherwise, f2fs cannot allocate remained free segments in the section since
SSR finds dirty segments only.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

The foreground GCs are triggered under not enough free sections.
So, we should not skip moving valid blocks in the victim segments.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

This patch removes a bitmap for victim segments selected by foreground GC, and
modifies the other bitmap for victim segments selected by background GC.

1) foreground GC bitmap
 : We don't need to manage this, since we just only one previous victim section
   number instead of the whole victim history.
   The f2fs uses the victim section number in order not to allocate currently
   GC'ed section to current active logs.

2) background GC bitmap
 : This bitmap is used to avoid selecting victims repeatedly by background GCs.
   In addition, the victims are able to be selected by foreground GCs, since
   there is no need to read victim blocks during foreground GCs.

   By the fact that the foreground GC reclaims segments in a section unit, it'd
   be better to manage this bitmap based on the section granularity.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

When allocating a new segment under the LFS mode, we should keep the section
boundary.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

In get_node_page, we do not need to call lock_page all the time.

If the node page is cached as uptodate,

1. grab_cache_page locks the page,
2. read_node_page unlocks the page, and
3. lock_page is called for further process.

Let's avoid this.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Let's use a macro to get the total number of sections.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

A macro should not use duplicate parameter names.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Use kmemdup instead of kzalloc and memcpy.

Signed-off-by: Alexandru Gheorghiu <gheorghiuandru@gmail.com>
Acked-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

When we recover fsync'ed data after power-off-recovery, we should guarantee
that any parent inode number should be correct for each direct inode blocks.

So, let's make the following rules.

- The fsync should do checkpoint to all the inodes that were experienced hard
links.

- So, the only normal files can be recovered by roll-forward.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

In the checkpoint flow, the f2fs investigates the total nat cache entries.
Previously, if an entry has NULL_ADDR, f2fs drops the entry and adds the
obsolete nid to the free nid list.
However, this free nid will be reused sooner, resulting in its nat entry miss.
In order to avoid this, we don't need to drop the nat cache entry at this moment.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>