Commit Graph

75 Commits

Author SHA1 Message Date
Changman Lee
1dbe415216 f2fs: large volume support
f2fs's cp has one page which consists of struct f2fs_checkpoint and
version bitmap of sit and nat. To support lots of segments, we need more
blocks for sit bitmap. So let's arrange sit bitmap as following:
+-----------------+------------+
| f2fs_checkpoint | sit bitmap |
| + nat bitmap    |            |
+-----------------+------------+
0                 4k        N blocks

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
[Jaegeuk Kim: simple code change for readability]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2014-06-04 13:34:30 +09:00
Chao Yu
e574843438 f2fs: add a tracepoint for f2fs_write_{meta,node,data}_pages
This patch adds a tracepoint for f2fs_write_{meta,node,data}_pages to trace when
pages are fsyncing/flushing.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:59 +09:00
Chao Yu
ecda0de343 f2fs: add a tracepoint for f2fs_write_{meta,node,data}_page
This patch adds a tracepoint for f2fs_write_{meta,node,data}_page to trace when
page is writting out.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:59 +09:00
Jaegeuk Kim
bde446866c f2fs: no need to wait on page writebck to meta pages
This patch removes grab_cache_page_write_begin for meta pages.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:58 +09:00
Fabian Frederick
b49ad51e6d f2fs: add static to get_max_meta_blks
inline get_max_meta_blks is only used in checkpoint.c
Use standard static inline format.

Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:55 +09:00
Jaegeuk Kim
ed57c27f73 f2fs: remove costly dirty_dir_inode operations
This patch removes list opeations in handling dirty dir inodes.
Previously, F2FS traverses whole the list of dirty dir inodes to check whether
there is an existing inode or not, resulting in heavy CPU overheads.

So this patch removes such the traverse operations by adding FI_DIRTY_DIR to
indicate the inode lies on the list or not.
Through this simple flag, we can remove redundant operations gracefully.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:54 +09:00
Jaegeuk Kim
76f60268e7 f2fs: call redirty_page_for_writepage
This patch replace some general codes with redirty_page_for_writepage, which
can be enabled after consideration on additional procedure like counting dirty
pages appropriately.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:54 +09:00
Jaegeuk Kim
1e87a78d95 f2fs: avoid to conduct roll-forward due to the remained garbage blocks
The f2fs always scans the next chain of direct node blocks.
But some garbage blocks are able to be remained due to no discard support or
SSR triggers.
This occasionally wreaks recovering wrong inodes that were used or BUG_ONs
due to reallocating node ids as follows.

When mount this f2fs image:
http://linuxtesting.org/downloads/f2fs_fault_image.zip
BUG_ON is triggered in f2fs driver (messages below are generated on
kernel 3.13.2; for other kernels output is similar):

kernel BUG at fs/f2fs/node.c:215!
 Call Trace:
 [<ffffffffa032ebad>] recover_inode_page+0x1fd/0x3e0 [f2fs]
 [<ffffffff811446e7>] ? __lock_page+0x67/0x70
 [<ffffffff81089990>] ? autoremove_wake_function+0x50/0x50
 [<ffffffffa0337788>] recover_fsync_data+0x1398/0x15d0 [f2fs]
 [<ffffffff812b9e5c>] ? selinux_d_instantiate+0x1c/0x20
 [<ffffffff811cb20b>] ? d_instantiate+0x5b/0x80
 [<ffffffffa0321044>] f2fs_fill_super+0xb04/0xbf0 [f2fs]
 [<ffffffff811b861e>] ? mount_bdev+0x7e/0x210
 [<ffffffff811b8769>] mount_bdev+0x1c9/0x210
 [<ffffffffa0320540>] ? validate_superblock+0x210/0x210 [f2fs]
 [<ffffffffa031cf8d>] f2fs_mount+0x1d/0x30 [f2fs]
 [<ffffffff811b9497>] mount_fs+0x47/0x1c0
 [<ffffffff81166e00>] ? __alloc_percpu+0x10/0x20
 [<ffffffff811d4032>] vfs_kern_mount+0x72/0x110
 [<ffffffff811d6763>] do_mount+0x493/0x910
 [<ffffffff811615cb>] ? strndup_user+0x5b/0x80
 [<ffffffff811d6c70>] SyS_mount+0x90/0xe0
 [<ffffffff8166f8d9>] system_call_fastpath+0x16/0x1b

Found by Linux File System Verification project (linuxtesting.org).

Reported-by: Andrey Tsyvarev <tsyvarev@ispras.ru>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-05-07 10:21:54 +09:00
Chao Yu
2d7b822ad9 f2fs: use list_for_each_entry{_safe} for simplyfying code
This patch use list_for_each_entry{_safe} instead of list_for_each{_safe} for
simplfying code.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-04-02 09:56:27 +09:00
Chao Yu
cf0ee0f09b f2fs: avoid free slab cache under spinlock
Move kmem_cache_free out of spinlock protection region for better performance.

Change log from v1:
 o remove spinlock protection for kmem_cache_free in destroy_node_manager
suggested by Jaegeuk Kim.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-04-02 09:56:12 +09:00
Jaegeuk Kim
3cb5ad152b f2fs: call f2fs_wait_on_page_writeback instead of native function
If a page is on writeback, f2fs can face with deadlock due to under writepages.
This is caused by merging IOs inside f2fs, so if it comes to detect, let's throw
merged IOs, which is implemented by f2fs_wait_on_page_writeback.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-20 22:10:04 +09:00
Jaegeuk Kim
50c8cdb35a f2fs: introduce nr_pages_to_write for segment alignment
This patch introduces nr_pages_to_write to align page writes to the segment
or other operational unit size, which can be tuned according to the system
environment.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-18 16:37:53 +09:00
Jaegeuk Kim
d3baf95da5 f2fs: increase pages_skipped when skipping writepages
This patch increases pages_skipped when skipping writepages.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-18 16:37:16 +09:00
Jaegeuk Kim
87d6f89094 f2fs: avoid small data writes by skipping writepages
This patch introduces nr_pages_to_skip(sbi, type) to determine writepages can
be skipped.
The dentry, node, and meta pages can be conrolled by F2FS without breaking the
FS consistency.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-18 13:58:59 +09:00
Jaegeuk Kim
f8b2c1f940 f2fs: introduce get_dirty_dents for readability
The get_dirty_dents gives us the number of dirty dentry pages.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-18 12:34:30 +09:00
Gu Zheng
e8512d2e0c f2fs: remove the unused ctor argument of f2fs_kmem_cache_create()
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-10 18:45:14 +09:00
Chao Yu
9cf3c3898a f2fs: fix dirty page accounting when redirty
We should de-account dirty counters for page when redirty in ->writepage().

Wu Fengguang described in 'commit 971767caf632190f77a40b4011c19948232eed75':
"writeback: fix dirtied pages accounting on redirty
De-account the accumulative dirty counters on page redirty.

Page redirties (very common in ext4) will introduce mismatch between
counters (a) and (b)

a) NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied
b) NR_WRITTEN, BDI_WRITTEN

This will introduce systematic errors in balanced_rate and result in
dirty page position errors (ie. the dirty pages are no longer balanced
around the global/bdi setpoints)."

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-28 13:09:08 +09:00
Chao Yu
81c1a0f13e f2fs: readahead contiguous SSA blocks for f2fs_gc
If there are multi segments in one section, we will read those SSA blocks which
have contiguous address one by one in f2fs_gc. It may lost performance, let's
read ahead SSA blocks by merge multi read request.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-27 20:40:36 +09:00
Changman Lee
942e0be621 f2fs: show counts of checkpoint in status
This patch shows the counts of checkpoint in f2fs' status.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-17 14:58:53 +09:00
Chao Yu
662befda25 f2fs: introduce ra_meta_pages to readahead CP/NAT/SIT pages
This patch help us to cleanup the readahead code by merging ra_{sit,nat}_pages
function into ra_meta_pages.
Additionally the new function is used to readahead cp block in
recover_orphan_inodes.

Change log from v1:
 o fix a deadloop bug pointed by Jaegeuk Kim.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-17 14:58:53 +09:00
Jaegeuk Kim
1fe54f9dd3 f2fs: clean up redundant function call
This patch integrates inode_[inc|dec]_dirty_dents with inc_page_count to remove
redundant calls.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-17 14:58:53 +09:00
Jaegeuk Kim
203681f65b f2fs: fix f2fs_write_meta_page at no checkpoint status
If f2fs entered errorneous checkpoint status, it should skip writing meta
pages instead of redirtying the pages out.
Otherwise, it cannot unmount the partition even though f2fs is under read-only
status.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-17 14:58:53 +09:00
Jaegeuk Kim
4ef51a8fcc f2fs: introduce NODE_MAPPING for code consistency
This patch adds NODE_MAPPING which is similar as META_MAPPING introduced by
Gu Zheng.

Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-22 18:41:08 +09:00
Gu Zheng
63f5384c9a f2fs: remove the orphan block page array
As the orphan_blocks may be max to 504, so it is not security
and rigorous to store such a large array in the kernel stack
as Dan Carpenter said.
In fact, grab_meta_page has locked the page in the page cache,
and we can use find_get_page() to fetch the page safely in the
downstream, so we can remove the page array directly.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-22 18:41:08 +09:00
Gu Zheng
9df27d982d f2fs: add help function META_MAPPING
Introduce help function META_MAPPING() to get the cache meta blocks'
address space.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-22 18:41:07 +09:00
Gu Zheng
17b692f60e f2fs: use spinlock rather than mutex for better speed
With the 2 previous changes, all the long time operations are moved out
of the protection region, so here we can use spinlock rather than mutex
(orphan_inode_mutex) for lower overhead.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-14 18:12:05 +09:00
Gu Zheng
c1ef372572 f2fs: move alloc new orphan node out of lock protection region
Move alloc new orphan node out of lock protection region.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-14 18:12:04 +09:00
Gu Zheng
4531929e39 f2fs: move grabing orphan pages out of protection region
Move grabing orphan block page out of protection region, and grab all
the orphan block pages ahead.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
[Jaegeuk Kim: remove unnecessary code pointed by Chao Yu]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-14 18:11:20 +09:00
Gu Zheng
0d47c1adc2 f2fs: convert max_orphans to a field of f2fs_sb_info
Previously, we need to calculate the max orphan num when we try to acquire an
orphan inode, but it's a stable value since the super block was inited. So
converting it to a field of f2fs_sb_info and use it directly when needed seems
a better choose.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-26 20:37:52 +09:00
Jaegeuk Kim
5459aa9770 f2fs: write dirty meta pages collectively
This patch enhances writing dirty meta pages collectively in background.
During the file data writes, it'd better avoid to write small dirty meta pages
frequently.
So let's give a chance to collect a number of dirty meta pages for a while.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:07 +09:00
Jaegeuk Kim
458e6197c3 f2fs: refactor bio->rw handling
This patch introduces f2fs_io_info to mitigate the complex parameter list.

struct f2fs_io_info {
	enum page_type type;		/* contains DATA/NODE/META/META_FLUSH */
	int rw;				/* contains R/RS/W/WS */
	int rw_flag;			/* contains REQ_META/REQ_PRIO */
}

1. f2fs_write_data_pages
 - DATA
 - WRITE_SYNC is set when wbc->WB_SYNC_ALL.

2. sync_node_pages
 - NODE
 - WRITE_SYNC all the time

3. sync_meta_pages
 - META
 - WRITE_SYNC all the time
 - REQ_META | REQ_PRIO all the time

 ** f2fs_submit_merged_bio() handles META_FLUSH.

4. ra_nat_pages, ra_sit_pages, ra_sum_pages
 - META
 - READ_SYNC

Cc: Fan Li <fanofcode.li@samsung.com>
Cc: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:06 +09:00
Jaegeuk Kim
6bacf52fb5 f2fs: add unlikely() macro for compiler more aggressively
This patch adds unlikely() macro into the most of codes.
The basic rule is to add that when:
- checking unusual errors,
- checking page mappings,
- and the other unlikely conditions.

Change log from v1:
 - Don't add unlikely for the NULL test and error test: advised by Andi Kleen.

Cc: Chao Yu <chao2.yu@samsung.com>
Cc: Andi Kleen <andi@firstfloor.org>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:06 +09:00
Chao Yu
cfb271d485 f2fs: add unlikely() macro for compiler optimization
As we know, some of our branch condition will rarely be true. So we could add
'unlikely' to let compiler optimize these code, by this way we could drop
unneeded 'jump' assemble code to improve performance.

change log:
 o add *unlikely* as many as possible across the whole source files at once
   suggested by Jaegeuk Kim.

Suggested-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:06 +09:00
Jaegeuk Kim
93dfe2ac51 f2fs: refactor bio-related operations
This patch integrates redundant bio operations on read and write IOs.

1. Move bio-related codes to the top of data.c.
2. Replace f2fs_submit_bio with f2fs_submit_merged_bio, which handles read
   bios additionally.
3. Introduce __submit_merged_bio to submit the merged bio.
4. Change f2fs_readpage to f2fs_submit_page_bio.
5. Introduce f2fs_submit_page_mbio to integrate previous submit_read_page and
   submit_write_page.

Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com >
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:05 +09:00
Chao Yu
8f99a946f3 f2fs: convert recover_orphan_inodes to void
The recover_orphan_inodes() returns no error all the time, so we don't need to
check its errors.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
[Jaegeuk Kim: add description]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:05 +09:00
Chao Yu
6947eea957 f2fs: avoid to calculate incorrect max orphan number
Because we will write node summaries when do_checkpoint with umount flag,
our number of max orphan blocks should minus NR_CURSEG_NODE_TYPE additional.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Shu Tan <shu.tan@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:04 +09:00
Jaegeuk Kim
f9a4e6df52 f2fs: bug fix on bit overflow from 32bits to 64bits
This patch fixes some bit overflows by the shift operations.

Dan Carpenter reported potential bugs on bit overflows as follows.

fs/f2fs/segment.c:910 submit_write_page()
	warn: should 'blk_addr << ((sbi)->log_blocksize - 9)' be a 64 bit type?
fs/f2fs/checkpoint.c:429 get_valid_checkpoint()
	warn: should '1 << ()' be a 64 bit type?
fs/f2fs/data.c:408 f2fs_readpage()
	warn: should 'blk_addr << ((sbi)->log_blocksize - 9)' be a 64 bit type?
fs/f2fs/data.c:457 submit_read_page()
	warn: should 'blk_addr << ((sbi)->log_blocksize - 9)' be a 64 bit type?
fs/f2fs/data.c:525 get_data_block_ro()
	warn: should 'i << blkbits' be a 64 bit type?

Bug-Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:04 +09:00
Gu Zheng
3679556794 f2fs: fix a potential out of range issue
Fix a potential out of range issue introduced by commit:
22fb72225a
f2fs: simplify write_orphan_inodes for better readable

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:04 +09:00
Changman Lee
03232305ff f2fs: send REQ_META or REQ_PRIO when reading meta area
Let's send REQ_META or REQ_PRIO when reading meta area such as NAT/SIT
etc.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:03 +09:00
Gu Zheng
ce3b7d80ed f2fs: move the list_head initialization into the lock protection region
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:02 +09:00
Gu Zheng
502c6e0bcd f2fs: simplify write_orphan_inodes for better readable
Simplify write_orphan_inodes for better readable. Because we hold the
orphan_inode_mutex, so it's safe to use list_for_each_entry instead of
list_for_each_safe.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23 10:18:01 +09:00
Changman Lee
fb51b5ef9c f2fs: cleanup waiting routine for writeback pages in cp
use genernal method supported by kernel

 o changes from v1
   If any waiter exists at end io, wake up it.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-11-08 14:10:29 +09:00
Jaegeuk Kim
5d56b6718a f2fs: add an option to avoid unnecessary BUG_ONs
If you want to remove unnecessary BUG_ONs, you can just turn off F2FS_CHECK_FS
in your kernel config.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-29 15:44:38 +09:00
Jaegeuk Kim
26c6b88799 f2fs: add tracepoint for set_page_dirty
This patch adds a tracepoint for set_page_dirty.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25 16:54:40 +09:00
Haicheng Li
aabe51364f f2fs: use bool for booleans
Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25 16:54:37 +09:00
Jaegeuk Kim
dcdfff6527 f2fs: clean up several status-related operations
This patch cleans up improper definitions that update some status information.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25 16:54:08 +09:00
Gu Zheng
7bd59381c8 f2fs: introduce f2fs_kmem_cache_alloc to hide the unfailed, kmem cache allocation
Introduce the unfailed version of kmem_cache_alloc named f2fs_kmem_cache_alloc
to hide the retry routine and make the code a bit cleaner.

v2:
   Fix the wrong use of 'retry' tag pointed out by Gao feng.
   Use more neat code to remove redundant tag suggested by Haicheng Li.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-22 20:16:02 +09:00
Jaegeuk Kim
87a9bd2656 f2fs: avoid to write during the recovery
This patch enhances the recovery routine not to write any data/node/meta until
its completion.
If any writes are sent to the disk, it could contaminate the written history
that will be used for further recovery.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-18 09:44:14 +09:00
Gu Zheng
e234088758 f2fs: avoid wait if IO end up when do_checkpoint for better performance
Previously, do_checkpoint() will call congestion_wait() for waiting the pages
(previous submitted node/meta/data pages) to be written back.
Because congestion_wait() will set a regular period (e.g. HZ / 50 ) for waiting, and
no additional wake up mechanism was introduced if IO ends up before regular period costed.
Yuan Zhong found there is a situation that after the pages have been written back,
but the checkpoint thread still wait for congestion_wait to exit.

So here we store checkpoint task into f2fs_sb when doing checkpoint, it'll wait for IO completes
if there's IO going on, and in the end IO path, wake up checkpoint task when IO ends up.

Thanks to Yuan Zhong's pre work about this problem.

Reported-by: Yuan Zhong <yuan.mark.zhong@samsung.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-18 09:44:14 +09:00
Gu Zheng
e479556bfd f2fs: use rw_sem instead of fs_lock(locks mutex)
The fs_locks is used to block other ops(ex, recovery) when doing checkpoint.
And each other operate routine(besides checkpoint) needs to acquire a fs_lock,
there is a terrible problem here, if these are too many concurrency threads acquiring
fs_lock, so that they will block each other and may lead to some performance problem,
but this is not the phenomenon we want to see.
Though there are some optimization patches introduced to enhance the usage of fs_lock,
but the thorough solution is using a *rw_sem* to replace the fs_lock.
Checkpoint routine takes write_sem, and other ops take read_sem, so that we can block
other ops(ex, recovery) when doing checkpoint, and other ops will not disturb each other,
this can avoid the problem described above completely.
Because of the weakness of rw_sem, the above change may introduce a potential problem
that the checkpoint thread might get starved if other threads are intensively locking
the read semaphore for I/O.(Pointed out by Xu Jin)
In order to avoid this, a wait_list is introduced, the appending read semaphore ops
will be dropped into the wait_list if checkpoint thread is waiting for write semaphore,
and will be waked up when checkpoint thread gives up write semaphore.
Thanks to Kim's previous review and test, and will be very glad to see other guys'
performance tests about this patch.

V2:
  -fix the potential starvation problem.
  -use more suitable func name suggested by Xu Jin.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: adjust minor coding standard]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-07 11:33:05 +09:00