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f2fs: enhance alloc_nid and build_free_nids flows

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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 commit is contained in:
Jaegeuk Kim 2013-04-25 16:05:51 +09:00
parent d70b4f53b9
commit 55008d845d
2 changed files with 37 additions and 47 deletions
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2
fs/f2fs/f2fs.h
View File

@ -190,7 +190,6 @@ static inline void set_raw_extent(struct extent_info *ext,
struct f2fs_nm_info {
block_t nat_blkaddr; /* base disk address of NAT */
nid_t max_nid; /* maximum possible node ids */
nid_t init_scan_nid; /* the first nid to be scanned */
nid_t next_scan_nid; /* the next nid to be scanned */
/* NAT cache management */
@ -360,6 +359,7 @@ struct f2fs_sb_info {
struct mutex writepages; /* mutex for writepages() */
unsigned char next_lock_num; /* round-robin global locks */
int por_doing; /* recovery is doing or not */
int on_build_free_nids; /* build_free_nids is doing */
/* for orphan inode management */
struct list_head orphan_inode_list; /* orphan inode list */

82
fs/f2fs/node.c
View File

@ -1309,14 +1309,14 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
struct f2fs_nm_info *nm_i = NM_I(sbi);
struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
struct f2fs_summary_block *sum = curseg->sum_blk;
nid_t nid = 0;
bool is_cycled = false;
int fcnt = 0;
int i;
int fcnt = 0, i = 0;
nid_t nid = nm_i->next_scan_nid;
nid = nm_i->next_scan_nid;
nm_i->init_scan_nid = nid;
/* Enough entries */
if (nm_i->fcnt > NAT_ENTRY_PER_BLOCK)
return;
/* readahead nat pages to be scanned */
ra_nat_pages(sbi, nid);
while (1) {
@ -1326,19 +1326,15 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
f2fs_put_page(page, 1);
nid += (NAT_ENTRY_PER_BLOCK - (nid % NAT_ENTRY_PER_BLOCK));
if (nid >= nm_i->max_nid) {
if (nid >= nm_i->max_nid)
nid = 0;
is_cycled = true;
}
if (fcnt > MAX_FREE_NIDS)
break;
if (is_cycled && nm_i->init_scan_nid <= nid)
if (i++ == FREE_NID_PAGES)
break;
}
/* go to the next nat page in order to reuse free nids first */
nm_i->next_scan_nid = nm_i->init_scan_nid + NAT_ENTRY_PER_BLOCK;
/* go to the next free nat pages to find free nids abundantly */
nm_i->next_scan_nid = nid;
/* find free nids from current sum_pages */
mutex_lock(&curseg->curseg_mutex);
@ -1375,41 +1371,36 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
struct free_nid *i = NULL;
struct list_head *this;
retry:
mutex_lock(&nm_i->build_lock);
if (!nm_i->fcnt) {
/* scan NAT in order to build free nid list */
build_free_nids(sbi);
if (!nm_i->fcnt) {
mutex_unlock(&nm_i->build_lock);
return false;
}
}
mutex_unlock(&nm_i->build_lock);
if (sbi->total_valid_node_count + 1 >= nm_i->max_nid)
return false;
/*
* We check fcnt again since previous check is racy as
* we didn't hold free_nid_list_lock. So other thread
* could consume all of free nids.
*/
spin_lock(&nm_i->free_nid_list_lock);
if (!nm_i->fcnt) {
/* We should not use stale free nids created by build_free_nids */
if (nm_i->fcnt && !sbi->on_build_free_nids) {
BUG_ON(list_empty(&nm_i->free_nid_list));
list_for_each(this, &nm_i->free_nid_list) {
i = list_entry(this, struct free_nid, list);
if (i->state == NID_NEW)
break;
}
BUG_ON(i->state != NID_NEW);
*nid = i->nid;
i->state = NID_ALLOC;
nm_i->fcnt--;
spin_unlock(&nm_i->free_nid_list_lock);
goto retry;
return true;
}
BUG_ON(list_empty(&nm_i->free_nid_list));
list_for_each(this, &nm_i->free_nid_list) {
i = list_entry(this, struct free_nid, list);
if (i->state == NID_NEW)
break;
}
BUG_ON(i->state != NID_NEW);
*nid = i->nid;
i->state = NID_ALLOC;
nm_i->fcnt--;
spin_unlock(&nm_i->free_nid_list_lock);
return true;
/* Let's scan nat pages and its caches to get free nids */
mutex_lock(&nm_i->build_lock);
sbi->on_build_free_nids = 1;
build_free_nids(sbi);
sbi->on_build_free_nids = 0;
mutex_unlock(&nm_i->build_lock);
goto retry;
}
/*
@ -1696,7 +1687,6 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
spin_lock_init(&nm_i->free_nid_list_lock);
rwlock_init(&nm_i->nat_tree_lock);
nm_i->init_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid);
nm_i->next_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid);
nm_i->bitmap_size = __bitmap_size(sbi, NAT_BITMAP);
version_bitmap = __bitmap_ptr(sbi, NAT_BITMAP);