linux-toradex.git/fs/f2fs/node.c, branch v4.4.100

f2fs: export ra_nid_pages to sysfs

2015-10-12T21:03:43+00:00

After finishing building free nid cache, we will try to readahead
asynchronously 4 more pages for the next reloading, the count of
readahead nid pages is fixed.

In some case, like SMR drive, read less sectors with fixed count
each time we trigger RA may be low efficient, since we will face
high seeking overhead, so we'd better let user to configure this
parameter from sysfs in specific workload.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: readahead for free nids building

2015-10-12T21:03:22+00:00

When there is no free nid in nid cache, all new node allocaters stop their
job to wait for reloading of free nids, however reloading is synchronous as
we will read 4 NAT pages for building nid cache, it cause the long latency.

This patch tries to readahead more NAT pages with READA request flag after
reloading of free nids. It helps to improve performance when users allocate
node id intensively.

Env: Sandisk 32G sd card
time for i in `seq 1 60000`; { echo -n > /mnt/f2fs/$i; echo XXXXXX > /mnt/f2fs/$i;}

Before:
real    0m2.814s
user    0m1.220s
sys     0m1.536s

After:
real    0m2.711s
user    0m1.136s
sys     0m1.568s

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: support lower priority asynchronous readahead in ra_meta_pages

2015-10-12T21:03:15+00:00

Now, we use ra_meta_pages to reads continuous physical blocks as much as
possible to improve performance of following reads. However, ra_meta_pages
uses a synchronous readahead approach by submitting bio with READ, as READ
is with high priority, it can not be used in the case of preloading blocks,
and it's not sure when these RAed pages will be used.

This patch supports asynchronous readahead in ra_meta_pages by tagging bio
with READA flag in order to allow preloading.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: don't tag REQ_META for temporary non-meta pages

2015-10-12T21:01:46+00:00

In recovery or checkpoint flow, we grab pages temperarily in meta inode's
mapping for caching temperary data, actually, datas in these pages were
not meta data of f2fs, but still we tag them with REQ_META flag. However,
lower device like eMMC may do some optimization for data of such type.
So in order to avoid wrong optimization, we'd better remove such flag
for temperary non-meta pages.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

Revert "f2fs: do not skip dentry block writes"

2015-10-12T20:38:02+00:00

The periodic checkpoint can resolve the previous issue.
So, now we can use this again to improve the reported performance regression:

https://lkml.org/lkml/2015/10/8/20

This reverts commit 15bec0ff5a9ba6d203178fa8772259df6207942a.

f2fs: do not skip dentry block writes

2015-10-09T23:20:54+00:00

Previously, we skip dentry block writes when wbc is SYNC_NONE with no memory
pressure and the number of dirty pages is pretty small.

But, we didn't skip for normal data writes, which gives us not much big impact
on overall performance.
Moreover, by skipping some data writes, kworker falls into infinite loop to try
to write blocks, when many dir inodes have only one dentry block.

So, this patch removes skipping data writes.

Signed-off-by: Jaegeuk Kim

f2fs: cover number of dirty node pages under node_write lock

2015-10-09T23:20:49+00:00

This number is referenced by checkpoint under node_write lock.

Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: fix to release inode correctly

2015-08-24T23:35:59+00:00

In following call stack, if unfortunately we lose all chances to truncate
inode page in remove_inode_page, eventually we will add the nid allocated
previously into free nid cache, this nid is with NID_NEW status and with
NEW_ADDR in its blkaddr pointer:

 - f2fs_create
  - f2fs_add_link
   - __f2fs_add_link
    - init_inode_metadata
     - new_inode_page
      - new_node_page
       - set_node_addr(, NEW_ADDR)
     - f2fs_init_acl   failed
     - remove_inode_page  failed
  - handle_failed_inode
   - remove_inode_page  failed
   - iput
    - f2fs_evict_inode
     - remove_inode_page  failed
     - alloc_nid_failed   cache a nid with valid blkaddr: NEW_ADDR

This may not only cause resource leak of previous inode, but also may cause
incorrect use of the previous blkaddr which is located in NO.nid node entry
when this nid is reused by others.

This patch tries to add this inode to orphan list if we fail to truncate
inode, so that we can obtain a second chance to release it in orphan
recovery flow.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: fix wrong pointer access during try_to_free_nids

2015-08-24T16:37:42+00:00

If we release the lock in list_for_each_entry_safe, we can lose the tmp
pointer by alloc_nid.

Signed-off-by: Jaegeuk Kim

f2fs: use __GFP_NOFAIL to avoid infinite loop

2015-08-24T16:37:21+00:00

__GFP_NOFAIL can avoid retrying the whole path of kmem_cache_alloc and
bio_alloc.
And, it also fixes the use cases of GFP_ATOMIC correctly.

Suggested-by: Chao Yu 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim