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f2fs: avoid f2fs_lock_op in f2fs_write_begin 

If f2fs_write_begin is to update data, we can bypass calling f2fs_lock_op() in
order to avoid the checkpoint latency in the write syscall.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim 2015-12-23 13:48:58 -08:00
parent 4aa69d5667
commit b4d07a3e1a
1 changed files with 34 additions and 8 deletions
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42
fs/f2fs/data.c
View File

@ -1418,10 +1418,16 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
pgoff_t index = page->index;
struct dnode_of_data dn;
struct page *ipage;
bool locked = false;
struct extent_info ei;
int err = 0;
f2fs_lock_op(sbi);
if (f2fs_has_inline_data(inode) ||
(pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
f2fs_lock_op(sbi);
locked = true;
}
restart:
/* check inline_data */
ipage = get_node_page(sbi, inode->i_ino);
if (IS_ERR(ipage)) {
@ -1436,22 +1442,42 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
read_inline_data(page, ipage);
set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
sync_inode_page(&dn);
goto done;
} else {
err = f2fs_convert_inline_page(&dn, page);
if (err)
goto err_out;
goto out;
if (dn.data_blkaddr == NULL_ADDR)
err = f2fs_get_block(&dn, index);
}
} else if (locked) {
err = f2fs_get_block(&dn, index);
} else {
if (f2fs_lookup_extent_cache(inode, index, &ei)) {
dn.data_blkaddr = ei.blk + index - ei.fofs;
} else {
bool restart = false;
/* hole case */
err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
if (err || (!err && dn.data_blkaddr == NULL_ADDR))
restart = true;
if (restart) {
f2fs_put_dnode(&dn);
f2fs_lock_op(sbi);
locked = true;
goto restart;
}
}
}
err = f2fs_get_block(&dn, index);
done:
/* convert_inline_page can make node_changed */
*blk_addr = dn.data_blkaddr;
*node_changed = dn.node_changed;
err_out:
out:
f2fs_put_dnode(&dn);
unlock_out:
f2fs_unlock_op(sbi);
if (locked)
f2fs_unlock_op(sbi);
return err;
}