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path: root/fs/f2fs/segment.c
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2014-04-07f2fs: introduce f2fs_issue_flush to avoid redundant flush issueJaegeuk Kim
Some storage devices show relatively high latencies to complete cache_flush commands, even though their normal IO speed is prettry much high. In such the case, it needs to merge cache_flush commands as much as possible to avoid issuing them redundantly. So, this patch introduces a mount option, "-o flush_merge", to mitigate such the overhead. If this option is enabled by user, F2FS merges the cache_flush commands and then issues just one cache_flush on behalf of them. Once the single command is finished, F2FS sends a completion signal to all the pending threads. Note that, this option can be used under a workload consisting of very intensive concurrent fsync calls, while the storage handles cache_flush commands slowly. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-04-02f2fs: fix to cover io->bio with io_rwsemJaegeuk Kim
In the f2fs_wait_on_page_writeback, io->bio should be covered by io_rwsem. Otherwise, the bio pointer can become a dangling pointer due to data races. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-04-02f2fs: use list_for_each_entry{_safe} for simplyfying codeChao Yu
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>
2014-04-01f2fs: avoid unnecessary bio submit when wait page writebackChao Yu
This patch introduce is_merged_page() to check whether current page is merged in f2fs bio cache. When page is not in cache, we can avoid submitting bio cache, resulting in having more chance to merge pages. Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-20f2fs: change reclaim rate in percentageJaegeuk Kim
It is more reasonable to determine the reclaiming rate of prefree segments according to the volume size, which is set to 5% by default. For example, if the volume is 128GB, the prefree segments are reclaimed when the number reaches to 6.4GB. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-18f2fs: avoid to return incorrect errno of read_normal_summariesChao Yu
We should return error number of read_normal_summaries instead of -EINVAL when read_normal_summaries failed. Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-10f2fs: optimize restore_node_summary slightlyGu Zheng
Previously, we ra_sum_pages to pre-read contiguous pages as more as possible, and if we fail to alloc more pages, an ENOMEM error will be reported upstream, even though we have alloced some pages yet. In fact, we can use the available pages to do the job partly, and continue the rest in the following circle. Only reporting ENOMEM upstream if we really can not alloc any available page. And another fix is ignoring dealing with the following pages if an EIO occurs when reading page from page_list. Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Reviewed-by: Chao Yu <chao2.yu@samsung.com> [Jaegeuk Kim: modify the flow for better neat code] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-03-10f2fs: remove the unused ctor argument of f2fs_kmem_cache_create()Gu Zheng
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-17f2fs: introduce ra_meta_pages to readahead CP/NAT/SIT pagesChao Yu
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>
2014-02-17f2fs: clean up with a macroJaegeuk Kim
This patch adds GET_BLKOFF_FROM_SEG0 to clean up some codes. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-02-17f2fs: handle dirty segments inside refresh_sit_entryJaegeuk Kim
This patch cleans up the refresh_sit_entry to handle locate_dirty_segments. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-22f2fs: add help function META_MAPPINGGu Zheng
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>
2014-01-20f2fs: clean checkpatch warningsChris Fries
Fixed a variety of trivial checkpatch warnings. The only delta should be some minor formatting on log strings that were split / too long. Signed-off-by: Chris Fries <cfries@motorola.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-14f2fs: remove the needless parameter of f2fs_wait_on_page_writebackYuan Zhong
"boo sync" parameter is never referenced in f2fs_wait_on_page_writeback. We should remove this parameter. Signed-off-by: Yuan Zhong <yuan.mark.zhong@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2014-01-08f2fs: improve write performance under frequent fsync callsJaegeuk Kim
When considering a bunch of data writes with very frequent fsync calls, we are able to think the following performance regression. N: Node IO, D: Data IO, IO scheduler: cfq Issue pending IOs D1 D2 D3 D4 D1 D2 D3 D4 N1 D2 D3 D4 N1 N2 N1 D3 D4 N2 D1 --> N1 can be selected by cfq becase of the same priority of N and D. Then D3 and D4 would be delayed, resuling in performance degradation. So, when processing the fsync call, it'd better give higher priority to data IOs than node IOs by assigning WRITE and WRITE_SYNC respectively. This patch improves the random wirte performance with frequent fsync calls by up to 10%. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: remove the rw_flag domain from f2fs_io_infoGu Zheng
When using the f2fs_io_info in the low level, we still need to merge the rw and rw_flag, so use the rw to hold all the io flags directly, and remove the rw_flag field. ps.It is based on the previous patch: f2fs: move all the bio initialization into __bio_alloc Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: introduce a new direct_IO write pathJaegeuk Kim
Previously, f2fs doesn't support direct IOs with high performance, which throws every write requests via the buffered write path, resulting in highly performance degradation due to memory opeations like copy_from_user. This patch introduces a new direct IO path in which every write requests are processed by generic blockdev_direct_IO() with enhanced get_block function. The get_data_block() in f2fs handles: 1. if original data blocks are allocates, then give them to blockdev. 2. otherwise, a. preallocate requested block addresses b. do not use extent cache for better performance c. give the block addresses to blockdev This policy induces that: - new allocated data are sequentially written to the disk - updated data are randomly written to the disk. - f2fs gives consistency on its file meta, not file data. Reviewed-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: introduce sysfs entry to control in-place-update policyJaegeuk Kim
This patch introduces new sysfs entries for users to control the policy of in-place-updates, namely IPU, in f2fs. Sometimes f2fs suffers from performance degradation due to its out-of-place update policy that produces many additional node block writes. If the storage performance is very dependant on the amount of data writes instead of IO patterns, we'd better drop this out-of-place update policy. This patch suggests 5 polcies and their triggering conditions as follows. [sysfs entry name = ipu_policy] 0: F2FS_IPU_FORCE all the time, 1: F2FS_IPU_SSR if SSR mode is activated, 2: F2FS_IPU_UTIL if FS utilization is over threashold, 3: F2FS_IPU_SSR_UTIL if SSR mode is activated and FS utilization is over threashold, 4: F2FS_IPU_DISABLE disable IPU. (=default option) [sysfs entry name = min_ipu_util] This parameter controls the threshold to trigger in-place-updates. The number indicates percentage of the filesystem utilization, and used by F2FS_IPU_UTIL and F2FS_IPU_SSR_UTIL policies. For more details, see need_inplace_update() in segment.h. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: refactor bio->rw handlingJaegeuk Kim
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>
2013-12-23f2fs: merge pages with the same sync_mode flagFan Li
Previously f2fs submits most of write requests using WRITE_SYNC, but f2fs_write_data_pages submits last write requests by sync_mode flags callers pass. This causes a performance problem since continuous pages with different sync flags can't be merged in cfq IO scheduler(thanks yu chao for pointing it out), and synchronous requests often take more time. This patch makes the following modifies to DATA writebacks: 1. every page will be written back using the sync mode caller pass. 2. only pages with the same sync mode can be merged in one bio request. These changes are restricted to DATA pages.Other types of writebacks are modified To remain synchronous. In my test with tiotest, f2fs sequence write performance is improved by about 7%-10% , and this patch has no obvious impact on other performance tests. Signed-off-by: Fan Li <fanofcode.li@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: refactor bio-related operationsJaegeuk Kim
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>
2013-12-23f2fs: remove the own bi_private allocationJaegeuk Kim
Previously f2fs allocates its own bi_private data structure all the time even though we don't use it. But, can we remove this bi_private allocation? This patch removes such the additional bi_private allocation. 1. Retrieve f2fs_sb_info from its page->mapping->host->i_sb. - This removes the usecases of bi_private in end_io. 2. Use bi_private only when we really need it. - The bi_private is used only when the checkpoint procedure is conducted. - When conducting the checkpoint, f2fs submits a META_FLUSH bio to wait its bio completion. - Since we have no dependancies to remove bi_private now, let's just use bi_private pointer as the completion pointer. Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: bug fix on bit overflow from 32bits to 64bitsJaegeuk Kim
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>
2013-12-23f2fs: send REQ_META or REQ_PRIO when reading meta areaChangman Lee
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>
2013-12-23f2fs: add detailed information of bio types in the tracepointsJaegeuk Kim
This patch inserts information of bio types in more detail. So, we can now see REQ_META and REQ_PRIO too. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: read contiguous sit entry pages by merging for mount performanceChao Yu
Previously we read sit entries page one by one, this method lost the chance of reading contiguous page together. So we read pages as contiguous as possible for better mount performance. change log: o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng suggested. o add mark_page_accessed() before release page to delay VM reclaiming. o remove '*order' for simplification of function as Jaegeuk Kim suggested. Signed-off-by: Chao Yu <chao2.yu@samsung.com> [Jaegeuk Kim: fix a bug on the block address calculation] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: adds a tracepoint for f2fs_submit_read_bioChao Yu
This patch adds a tracepoint for f2fs_submit_read_bio. Signed-off-by: Chao Yu <chao2.yu@samsung.com> [Jaegeuk Kim: integrate tracepoints of f2fs_submit_read(_write)_bio] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: adds a tracepoint for submit_read_pageChao Yu
This patch adds a tracepoint for submit_read_page. Signed-off-by: Chao Yu <chao2.yu@samsung.com> [Jaegeuk Kim: integrate tracepoints of f2fs_submit_read(_write)_page] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: introduce a bio array for per-page write biosJaegeuk Kim
The f2fs has three bio types, NODE, DATA, and META, and manages some data structures per each bio types. The codes are a little bit messy, thus, this patch introduces a bio array which groups individual data structures as follows. struct f2fs_bio_info { struct bio *bio; /* bios to merge */ sector_t last_block_in_bio; /* last block number */ struct mutex io_mutex; /* mutex for bio */ }; struct f2fs_sb_info { ... struct f2fs_bio_info write_io[NR_PAGE_TYPE]; /* for write bios */ ... }; The code changes from this new data structure are trivial. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: use sbi->write_mutex for write biosJaegeuk Kim
This patch removes an unnecessary semaphore (i.e., sbi->bio_sem). There is no reason to use the semaphore when f2fs submits read and write IOs. Instead, let's use a write mutex and cover the sbi->bio[] by the lock. Change log from v1: o split write_mutex suggested by Chao Yu Chao described, "All DATA/NODE/META bio buffers in superblock is protected by 'sbi->write_mutex', but each bio buffer area is independent, So we should split write_mutex to three for DATA/NODE/META." Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: clean up the do_submit_bio flowJaegeuk Kim
This patch introduces PAGE_TYPE_OF_BIO() and cleans up do_submit_bio() with it. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: add a tracepoint for f2fs_issue_discardJaegeuk Kim
This patch adds a tracepoint for f2fs_issue_discard. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: introduce f2fs_issue_discard() to clean upJaegeuk Kim
Change log from v1: o fix 32bit drops reported by Dan Carpenter This patch adds f2fs_issue_discard() to clean up blkdev_issue_discard() flows. Dan carpenter reported: "block_t is a 32 bit type and sector_t is a 64 bit type. The upper 32 bits of the sector_t are not used because the shift will wrap." Bug-Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: add key functions for small discardsJaegeuk Kim
This patch adds key functions to activate the small discard feature. Note that this procedure is conducted during the checkpoint only. In flush_sit_entries(), when a new dirty sit entry is flushed, f2fs calls add_discard_addrs() which searches candidates to be discarded. The candidates should be marked *invalidated* and also previous checkpoint recognizes it as *valid*. At the end of a checkpoint procedure, f2fs throws discards based on the discard entry list. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: add a slab cache entry for small discardsJaegeuk Kim
This patch adds a slab cache entry for small discards. Each entry consists of: struct discard_entry { struct list_head list; /* list head */ block_t blkaddr; /* block address to be discarded */ int len; /* # of consecutive blocks of the discard */ }; Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: improve searching speed of __next_free_blkoffChangman Lee
To find a zero bit using the result of OR operation between ckpt_valid_map and cur_valid_map is more fast than find a zero bit in each bitmap. Signed-off-by: Changman Lee <cm224.lee@samsung.com> [Jaegeuk Kim: adjust changed function name] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-12-23f2fs: introduce __find_rev_next(_zero)_bitChangman Lee
When f2fs_set_bit is used, in a byte MSB and LSB is reversed, in that case we can use __find_rev_next_bit or __find_rev_next_zero_bit. Signed-off-by: Changman Lee <cm224.lee@samsung.com> [Jaegeuk Kim: change the function names] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-11-11f2fs: issue more large discard commandChangman Lee
o Changes from v1 Use find_next(_zero)_bit suggested by jg.kim When f2fs issues discard command, if segment is contiguous, let's issue more large segment to gather adjacent segments. ** blktrace ** 179,1 0 5859 42.619023770 971 C D 131072 + 2097152 [0] 179,1 0 33665 108.840475468 971 C D 2228224 + 2494464 [0] 179,1 0 33671 109.131616427 971 C D 14909440 + 344064 [0] 179,1 0 33677 109.137100677 971 C D 15261696 + 4096 [0] Signed-off-by: Changman Lee <cm224.lee@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-11-08f2fs: cleanup waiting routine for writeback pages in cpChangman Lee
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>
2013-11-06f2fs: avoid to use a NULL point in destroy_segment_managerChao Yu
A NULL point should avoid to be used in destroy_segment_manager after allocating memory fail for f2fs_sm_info. Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-30f2fs: change the method of calculating the number summary blocksFan Li
npages_for_summary_flush uses (SUMMARY_SIZE + 1) as the size of a f2fs_summary while its actual size is SUMMARY_SIZE. So the result sometimes is bigger than actual number by one, which causes checkpoint can't be written into disk contiguously, and sometimes summary blocks can't be compacted like they should. Besides, when writing summary blocks into pages, if remain space in a page isn't big enough for one f2fs_summary, it will be left unused, current code seems not to take it into account. Signed-off-by: Fan Li <fanofcode.li@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-29f2fs: add an option to avoid unnecessary BUG_ONsJaegeuk Kim
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>
2013-10-28f2fs: remove unnecessary segment bitmap updatesChangman Lee
Only one dirty type is set in __locate_dirty_segment and we can know dirty type of segment. So we don't need to check other dirty types. Signed-off-by: Changman Lee <cm224.lee@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25f2fs: remove redundant set_page_dirty from write_compacted_summariesChao Yu
Previously, set_page_dirty is called every time after writting one summary info into compacted summary page, To avoid redundant set_page_dirty, we only call set_page_dirty before release page. Signed-off-by: Yu Chao <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25f2fs: introduce f2fs_balance_fs_bg for some background jobsJaegeuk Kim
This patch merges some background jobs into this new function. Signed-off-by: Changman Lee <cm224.lee@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25f2fs: reclaim prefree segments periodicallyJaegeuk Kim
Previously, f2fs postpones reclaiming prefree segments into free segments as much as possible. However, if user writes and deletes a bunch of data without any sync or fsync calls, some flash storages can suffer from garbage collections. So, this patch adds the reclaiming codes to f2fs_write_node_pages and background GC thread. If there are a lot of prefree segments, let's do checkpoint so that f2fs submits discard commands for the prefree regions to the flash storage. Signed-off-by: Changman Lee <cm224.lee@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-25f2fs: clean up several status-related operationsJaegeuk Kim
This patch cleans up improper definitions that update some status information. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-22f2fs: no need to check other dirty_segmap when the seg has been foundHaicheng Li
Because one dirty seg can only be mapped to one dirty_type. Otherwise, it's a bug. Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> [Jaegeuk Kim: modify a comment related to this patch] Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-22f2fs: use true and false for boolean valueHaicheng Li
Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-10-18f2fs: avoid wait if IO end up when do_checkpoint for better performanceGu Zheng
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>