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f2fs: introduce free nid bitmap

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In scenario of intensively node allocation, free nids will be ran out
soon, then it needs to stop to load free nids by traversing NAT blocks,
in worse case, if NAT blocks does not be cached in memory, it generates
IOs which slows down our foreground operations.

In order to speed up node allocation, in this patch we introduce a new
free_nid_bitmap array, so there is an bitmap table for each NAT block,
Once the NAT block is loaded, related bitmap cache will be switched on,
and bitmap will be set during traversing nat entries in NAT block, later
we can query and update nid usage status in memory completely.

With such implementation, I expect performance of node allocation can be
improved in the long-term after filesystem image is mounted.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2017-02-23 10:53:49 +08:00 • committed by Jaegeuk Kim
parent ced2c7ea8e
commit 4ac912427c
4 changed files with 120 additions and 10 deletions
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1
include/linux/f2fs_fs.h
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@ -279,6 +279,7 @@ struct f2fs_node {
* For NAT entries
*/
#define NAT_ENTRY_PER_BLOCK (PAGE_SIZE / sizeof(struct f2fs_nat_entry))
#define NAT_ENTRY_BITMAP_SIZE ((NAT_ENTRY_PER_BLOCK + 7) / 8)
struct f2fs_nat_entry {
__u8 version; /* latest version of cached nat entry */