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Date: Wed, 26 May 2021 18:40:03 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: Chao Yu <yuchao0@...wei.com>,
linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] f2fs: swap: remove dead codes
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.
>
> 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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