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Date: Thu, 27 May 2021 10:12:25 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
CC: <linux-f2fs-devel@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] f2fs: swap: remove dead codes
On 2021/5/27 9:40, Jaegeuk Kim wrote:
> On 05/26, Chao Yu wrote:
>> On 2021/5/26 21:30, Jaegeuk Kim wrote:
>>> On 05/26, Chao Yu wrote:
>>>> After commit af4b6b8edf6a ("f2fs: introduce check_swap_activate_fast()"),
>>>> we will never run into original logic of check_swap_activate() before
>>>> f2fs supports non 4k-sized page, so let's delete those dead codes.
>>>
>>> Why not keeping this for large page support in future maybe?
>>
>> Well, if so, at that time, it would be better to refactor
>> check_swap_activate_fast() implementation based on f2fs_map_block() rather
>> than refactoring check_swap_activate() implementation based on low efficient
>> bmap()?
>
> Let's first check whether we support large page. Have you quickly tested it?
> If we support it now and current flow is just inefficient, I'd say keeping but
> refactoring it later.
Let me check this, but I guess it missed to handle large page in lots of flows,
not sure where we may panic at... :(
Thanks,
>
>>
>> Thanks,
>>
>>>
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>>>> ---
>>>> fs/f2fs/data.c | 171 +------------------------------------------------
>>>> 1 file changed, 3 insertions(+), 168 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>> index 3058c7e28b11..9c23fde93b76 100644
>>>> --- a/fs/f2fs/data.c
>>>> +++ b/fs/f2fs/data.c
>>>> @@ -3830,67 +3830,7 @@ int f2fs_migrate_page(struct address_space *mapping,
>>>> #endif
>>>> #ifdef CONFIG_SWAP
>>>> -static int f2fs_is_file_aligned(struct inode *inode)
>>>> -{
>>>> - struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>>> - block_t main_blkaddr = SM_I(sbi)->main_blkaddr;
>>>> - block_t cur_lblock;
>>>> - block_t last_lblock;
>>>> - block_t pblock;
>>>> - unsigned long nr_pblocks;
>>>> - unsigned int blocks_per_sec = BLKS_PER_SEC(sbi);
>>>> - unsigned int not_aligned = 0;
>>>> - int ret = 0;
>>>> -
>>>> - cur_lblock = 0;
>>>> - last_lblock = bytes_to_blks(inode, i_size_read(inode));
>>>> -
>>>> - while (cur_lblock < last_lblock) {
>>>> - struct f2fs_map_blocks map;
>>>> -
>>>> - memset(&map, 0, sizeof(map));
>>>> - map.m_lblk = cur_lblock;
>>>> - map.m_len = last_lblock - cur_lblock;
>>>> - map.m_next_pgofs = NULL;
>>>> - map.m_next_extent = NULL;
>>>> - map.m_seg_type = NO_CHECK_TYPE;
>>>> - map.m_may_create = false;
>>>> -
>>>> - ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
>>>> - if (ret)
>>>> - goto out;
>>>> -
>>>> - /* hole */
>>>> - if (!(map.m_flags & F2FS_MAP_FLAGS)) {
>>>> - f2fs_err(sbi, "Swapfile has holes\n");
>>>> - ret = -ENOENT;
>>>> - goto out;
>>>> - }
>>>> -
>>>> - pblock = map.m_pblk;
>>>> - nr_pblocks = map.m_len;
>>>> -
>>>> - if ((pblock - main_blkaddr) & (blocks_per_sec - 1) ||
>>>> - nr_pblocks & (blocks_per_sec - 1)) {
>>>> - if (f2fs_is_pinned_file(inode)) {
>>>> - f2fs_err(sbi, "Swapfile does not align to section");
>>>> - ret = -EINVAL;
>>>> - goto out;
>>>> - }
>>>> - not_aligned++;
>>>> - }
>>>> -
>>>> - cur_lblock += nr_pblocks;
>>>> - }
>>>> - if (not_aligned)
>>>> - f2fs_warn(sbi, "Swapfile (%u) is not align to section: \n"
>>>> - "\t1) creat(), 2) ioctl(F2FS_IOC_SET_PIN_FILE), 3) fallocate()",
>>>> - not_aligned);
>>>> -out:
>>>> - return ret;
>>>> -}
>>>> -
>>>> -static int check_swap_activate_fast(struct swap_info_struct *sis,
>>>> +static int check_swap_activate(struct swap_info_struct *sis,
>>>> struct file *swap_file, sector_t *span)
>>>> {
>>>> struct address_space *mapping = swap_file->f_mapping;
>>>> @@ -3907,6 +3847,8 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
>>>> unsigned int not_aligned = 0;
>>>> int ret = 0;
>>>> + f2fs_bug_on(sbi, PAGE_SIZE != F2FS_BLKSIZE);
>>>> +
>>>> /*
>>>> * Map all the blocks into the extent list. This code doesn't try
>>>> * to be very smart.
>>>> @@ -3986,113 +3928,6 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
>>>> return ret;
>>>> }
>>>> -/* 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)
>>>> -{
>>>> - struct address_space *mapping = swap_file->f_mapping;
>>>> - struct inode *inode = mapping->host;
>>>> - struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>>> - unsigned blocks_per_page;
>>>> - unsigned long page_no;
>>>> - sector_t probe_block;
>>>> - sector_t last_block;
>>>> - sector_t lowest_block = -1;
>>>> - sector_t highest_block = 0;
>>>> - int nr_extents = 0;
>>>> - int ret = 0;
>>>> -
>>>> - if (PAGE_SIZE == F2FS_BLKSIZE)
>>>> - return check_swap_activate_fast(sis, swap_file, span);
>>>> -
>>>> - ret = f2fs_is_file_aligned(inode);
>>>> - if (ret)
>>>> - goto out;
>>>> -
>>>> - blocks_per_page = bytes_to_blks(inode, PAGE_SIZE);
>>>> -
>>>> - /*
>>>> - * Map all the blocks into the extent list. This code doesn't try
>>>> - * to be very smart.
>>>> - */
>>>> - probe_block = 0;
>>>> - page_no = 0;
>>>> - last_block = bytes_to_blks(inode, i_size_read(inode));
>>>> - while ((probe_block + blocks_per_page) <= last_block &&
>>>> - page_no < sis->max) {
>>>> - unsigned block_in_page;
>>>> - sector_t first_block;
>>>> - sector_t block = 0;
>>>> -
>>>> - cond_resched();
>>>> -
>>>> - block = probe_block;
>>>> - ret = bmap(inode, &block);
>>>> - if (ret)
>>>> - goto out;
>>>> - if (!block)
>>>> - goto bad_bmap;
>>>> - first_block = block;
>>>> -
>>>> - /*
>>>> - * It must be PAGE_SIZE aligned on-disk
>>>> - */
>>>> - if (first_block & (blocks_per_page - 1)) {
>>>> - probe_block++;
>>>> - goto reprobe;
>>>> - }
>>>> -
>>>> - for (block_in_page = 1; block_in_page < blocks_per_page;
>>>> - block_in_page++) {
>>>> -
>>>> - block = probe_block + block_in_page;
>>>> - ret = bmap(inode, &block);
>>>> - if (ret)
>>>> - goto out;
>>>> - if (!block)
>>>> - goto bad_bmap;
>>>> -
>>>> - if (block != first_block + block_in_page) {
>>>> - /* Discontiguity */
>>>> - probe_block++;
>>>> - goto reprobe;
>>>> - }
>>>> - }
>>>> -
>>>> - first_block >>= (PAGE_SHIFT - inode->i_blkbits);
>>>> - if (page_no) { /* exclude the header page */
>>>> - if (first_block < lowest_block)
>>>> - lowest_block = first_block;
>>>> - if (first_block > highest_block)
>>>> - highest_block = first_block;
>>>> - }
>>>> -
>>>> - /*
>>>> - * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
>>>> - */
>>>> - ret = add_swap_extent(sis, page_no, 1, first_block);
>>>> - if (ret < 0)
>>>> - goto out;
>>>> - nr_extents += ret;
>>>> - page_no++;
>>>> - probe_block += blocks_per_page;
>>>> -reprobe:
>>>> - continue;
>>>> - }
>>>> - ret = nr_extents;
>>>> - *span = 1 + highest_block - lowest_block;
>>>> - if (page_no == 0)
>>>> - page_no = 1; /* force Empty message */
>>>> - sis->max = page_no;
>>>> - sis->pages = page_no - 1;
>>>> - sis->highest_bit = page_no - 1;
>>>> -out:
>>>> - return ret;
>>>> -bad_bmap:
>>>> - f2fs_err(sbi, "Swapfile has holes\n");
>>>> - return -EINVAL;
>>>> -}
>>>> -
>>>> static int f2fs_swap_activate(struct swap_info_struct *sis, struct file *file,
>>>> sector_t *span)
>>>> {
>>>> --
>>>> 2.29.2
> .
>
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