f2fs: introduce check_swap_activate_fast()

check_swap_activate() will lookup block mapping via bmap() one by one, so
its performance is very bad, this patch introduces check_swap_activate_fast()
to use f2fs_fiemap() to boost this process, since f2fs_fiemap() will lookup
block mappings in batch, therefore, it can improve swapon()'s performance
significantly.

Note that this enhancement only works when page size is equal to f2fs' block
size.

Testcase: (backend device: zram)
- touch file
- pin & fallocate file to 8GB
- mkswap file
- swapon file

Before:
real	0m2.999s
user	0m0.000s
sys	0m2.980s

After:
real	0m0.081s
user	0m0.000s
sys	0m0.064s

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ee87407602fa7982d0c5dd019dc2cf00ecbefff6..be4da52604edc19f6742fa8936ef32405282fae6 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3883,6 +3883,83 @@ int f2fs_migrate_page(struct address_space *mapping,
 #endif
 
 #ifdef CONFIG_SWAP
+static int check_swap_activate_fast(struct swap_info_struct *sis,
+                               struct file *swap_file, sector_t *span)
+{
+       struct address_space *mapping = swap_file->f_mapping;
+       struct inode *inode = mapping->host;
+       sector_t cur_lblock;
+       sector_t last_lblock;
+       sector_t pblock;
+       sector_t lowest_pblock = -1;
+       sector_t highest_pblock = 0;
+       int nr_extents = 0;
+       unsigned long nr_pblocks;
+       unsigned long len;
+       int ret;
+
+       /*
+        * Map all the blocks into the extent list.  This code doesn't try
+        * to be very smart.
+        */
+       cur_lblock = 0;
+       last_lblock = logical_to_blk(inode, i_size_read(inode));
+       len = i_size_read(inode);
+
+       while (cur_lblock <= last_lblock && cur_lblock < sis->max) {
+               struct buffer_head map_bh;
+               pgoff_t next_pgofs;
+
+               cond_resched();
+
+               memset(&map_bh, 0, sizeof(struct buffer_head));
+               map_bh.b_size = len - cur_lblock;
+
+               ret = get_data_block(inode, cur_lblock, &map_bh, 0,
+                                       F2FS_GET_BLOCK_FIEMAP, &next_pgofs);
+               if (ret)
+                       goto err_out;
+
+               /* hole */
+               if (!buffer_mapped(&map_bh))
+                       goto err_out;
+
+               pblock = map_bh.b_blocknr;
+               nr_pblocks = logical_to_blk(inode, map_bh.b_size);
+
+               if (cur_lblock + nr_pblocks >= sis->max)
+                       nr_pblocks = sis->max - cur_lblock;
+
+               if (cur_lblock) {       /* exclude the header page */
+                       if (pblock < lowest_pblock)
+                               lowest_pblock = pblock;
+                       if (pblock + nr_pblocks - 1 > highest_pblock)
+                               highest_pblock = pblock + nr_pblocks - 1;
+               }
+
+               /*
+                * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
+                */
+               ret = add_swap_extent(sis, cur_lblock, nr_pblocks, pblock);
+               if (ret < 0)
+                       goto out;
+               nr_extents += ret;
+               cur_lblock += nr_pblocks;
+       }
+       ret = nr_extents;
+       *span = 1 + highest_pblock - lowest_pblock;
+       if (cur_lblock == 0)
+               cur_lblock = 1; /* force Empty message */
+       sis->max = cur_lblock;
+       sis->pages = cur_lblock - 1;
+       sis->highest_bit = cur_lblock - 1;
+out:
+       return ret;
+err_out:
+       pr_err("swapon: swapfile has holes\n");
+       return -EINVAL;
+}
+
 /* Copied from generic_swapfile_activate() to check any holes */
 static int check_swap_activate(struct swap_info_struct *sis,
                                struct file *swap_file, sector_t *span)
@@ -3899,6 +3976,9 @@ static int check_swap_activate(struct swap_info_struct *sis,
        int nr_extents = 0;
        int ret;
 
+       if (PAGE_SIZE == F2FS_BLKSIZE)
+               return check_swap_activate_fast(sis, swap_file, span);
+
        blkbits = inode->i_blkbits;
        blocks_per_page = PAGE_SIZE >> blkbits;