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Date: Thu, 22 Oct 2015 11:11:44 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: support file defragment
Hi,
On Thu, Oct 22, 2015 at 07:59:14PM +0800, Chao Yu wrote:
> This patch introduces a new ioctl F2FS_IOC_DEFRAGMENT to support file
> defragment in a specified range of regular file.
>
> This ioctl can be used in very limited workload: if user expects high
> sequential read performance in randomly written file, this interface
> can be used for defragmentation, after that file can be written as
> continuous as possible in the device.
>
> Meanwhile, it has side-effect, it will make holes in segments where
> blocks located originally, so it's better to trigger GC to eliminate
> fragment in segments.
>
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> ---
> fs/f2fs/data.c | 6 +-
> fs/f2fs/f2fs.h | 8 +++
> fs/f2fs/file.c | 200 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 213 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 972eab7..5bb375a 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -566,7 +566,7 @@ out:
> * b. do not use extent cache for better performance
> * c. give the block addresses to blockdev
> */
> -static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> +int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> int create, int flag)
> {
> unsigned int maxblocks = map->m_len;
> @@ -1354,6 +1354,10 @@ static int f2fs_write_data_pages(struct address_space *mapping,
> available_free_memory(sbi, DIRTY_DENTS))
> goto skip_write;
>
> + /* skip writing during file defragment */
> + if (is_inode_flag_set(F2FS_I(inode), FI_DO_DEFRAG))
> + goto skip_write;
> +
> /* during POR, we don't need to trigger writepage at all. */
> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
> goto skip_write;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 9db5500..068813c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -234,6 +234,7 @@ static inline bool __has_cursum_space(struct f2fs_summary_block *sum, int size,
> #define F2FS_IOC_ABORT_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 5)
> #define F2FS_IOC_GARBAGE_COLLECT _IO(F2FS_IOCTL_MAGIC, 6)
> #define F2FS_IOC_WRITE_CHECKPOINT _IO(F2FS_IOCTL_MAGIC, 7)
> +#define F2FS_IOC_DEFRAGMENT _IO(F2FS_IOCTL_MAGIC, 8)
>
> #define F2FS_IOC_SET_ENCRYPTION_POLICY \
> _IOR('f', 19, struct f2fs_encryption_policy)
> @@ -260,6 +261,11 @@ static inline bool __has_cursum_space(struct f2fs_summary_block *sum, int size,
> #define F2FS_IOC32_SETFLAGS FS_IOC32_SETFLAGS
> #endif
>
> +struct f2fs_defragment {
> + u64 start;
> + u64 len;
> +};
> +
> /*
> * For INODE and NODE manager
> */
> @@ -1416,6 +1422,7 @@ enum {
> FI_DROP_CACHE, /* drop dirty page cache */
> FI_DATA_EXIST, /* indicate data exists */
> FI_INLINE_DOTS, /* indicate inline dot dentries */
> + FI_DO_DEFRAG, /* indicate defragment is running */
> };
>
> static inline void set_inode_flag(struct f2fs_inode_info *fi, int flag)
> @@ -1847,6 +1854,7 @@ struct page *find_data_page(struct inode *, pgoff_t);
> struct page *get_lock_data_page(struct inode *, pgoff_t, bool);
> struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
> int do_write_data_page(struct f2fs_io_info *);
> +int f2fs_map_blocks(struct inode *, struct f2fs_map_blocks *, int, int);
> int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *, u64, u64);
> void f2fs_invalidate_page(struct page *, unsigned int, unsigned int);
> int f2fs_release_page(struct page *, gfp_t);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index a197215..ad59694 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1646,6 +1646,204 @@ static int f2fs_ioc_write_checkpoint(struct file *filp, unsigned long arg)
> return 0;
> }
>
> +static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
> + struct file *filp,
> + struct f2fs_defragment *range)
> +{
> + struct inode *inode = file_inode(filp);
> + struct f2fs_map_blocks map;
> + struct extent_info ei;
> + pgoff_t pg_start, pg_end;
> + unsigned int blk_per_seg = 1 << sbi->log_blocks_per_seg;
> + unsigned int total = 0, sec_num;
> + unsigned int pages_per_sec = sbi->segs_per_sec *
> + (1 << sbi->log_blocks_per_seg);
> + block_t blk_end = 0;
> + bool fragmented = false;
> + int err = 0;
> +
> + pg_start = range->start >> PAGE_CACHE_SHIFT;
> + pg_end = (range->start + range->len) >> PAGE_CACHE_SHIFT;
> +
> + f2fs_balance_fs(sbi);
> +
> + mutex_lock(&inode->i_mutex);
> +
> + /* writeback all dirty pages in the range */
> + err = filemap_write_and_wait_range(inode->i_mapping, range->start,
> + range->start + range->len);
> + if (err)
> + goto out;
> +
> + /*
> + * lookup mapping info in extent cache, skip defragmenting if physical
> + * block addresses are continuous.
> + */
> + if (f2fs_lookup_extent_cache(inode, pg_start, &ei)) {
> + if (ei.fofs + ei.len >= pg_end)
> + goto out;
> + }
> +
> + map.m_lblk = pg_start;
> + map.m_len = pg_end - pg_start;
> +
> + /*
> + * lookup mapping info in dnode page cache, skip defragmenting if all
> + * physical block addresses are continuous even if there are hole(s)
> + * in logical blocks.
> + */
> + while (map.m_lblk < pg_end) {
> + map.m_flags = 0;
> + err = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_READ);
How about using f2fs_fiemap to get the extent information?
> + if (err)
> + goto out;
> +
> + if (!(map.m_flags & F2FS_MAP_FLAGS)) {
> + map.m_lblk++;
> + map.m_len--;
> + continue;
> + }
> +
> + if (blk_end && blk_end != map.m_pblk) {
> + fragmented = true;
> + break;
> + }
> + blk_end = map.m_pblk + map.m_len;
> +
> + map.m_lblk += map.m_len;
> + map.m_len = pg_end - map.m_lblk;
> + }
> +
> + if (!fragmented)
> + goto out;
> +
> + map.m_lblk = pg_start;
> + map.m_len = pg_end - pg_start;
> +
> + sec_num = (map.m_len + pages_per_sec - 1) / pages_per_sec;
> +
> + if (has_not_enough_free_secs(sbi, sec_num))
Later, ->writepage will handle this?
> + goto out;
> +
> + while (map.m_lblk < pg_end) {
> + pgoff_t idx;
> + int cnt = 0;
What about this?
for_each_extents(extent_info) {
page = get_lock_data_page(inode, idx, true);
set_page_dirty(page);
}
filemap_fdatawrite();
Thanks,
> +
> +do_map:
> + map.m_flags = 0;
> + err = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_READ);
> + if (err)
> + goto out;
> +
> + if (!(map.m_flags & F2FS_MAP_FLAGS)) {
> + map.m_lblk++;
> + continue;
> + }
> +
> + set_inode_flag(F2FS_I(inode), FI_DO_DEFRAG);
> +
> + idx = map.m_lblk;
> + while (idx < map.m_lblk + map.m_len && cnt < blk_per_seg) {
> + struct address_space *mapping = inode->i_mapping;
> + struct page *page;
> +
> + page = find_or_create_page(mapping, idx, GFP_NOFS);
> + if (!page) {
> + err = -ENOMEM;
> + goto out;
> + }
> +
> + f2fs_wait_on_page_writeback(page, DATA);
> +
> + if (!PageUptodate(page)) {
> + err = mapping->a_ops->readpage(filp, page);
> + if (unlikely(err)) {
> + f2fs_put_page(page, 0);
> + goto out;
> + }
> +
> + lock_page_killable(page);
> +
> + if (!PageUptodate(page)) {
> + f2fs_put_page(page, 1);
> + err = -EIO;
> + goto out;
> + }
> + }
> + set_page_dirty(page);
> + f2fs_put_page(page, 1);
> +
> + idx++;
> + cnt++;
> + total++;
> + }
> +
> + map.m_lblk = idx;
> + map.m_len = pg_end - idx;
> +
> + if (idx < pg_end && cnt < blk_per_seg)
> + goto do_map;
> +
> + clear_inode_flag(F2FS_I(inode), FI_DO_DEFRAG);
> +
> + err = filemap_fdatawrite(inode->i_mapping);
> + if (err)
> + goto out;
> + }
> +out:
> + mutex_unlock(&inode->i_mutex);
> + if (!err)
> + range->len = (u64)total << PAGE_CACHE_SHIFT;
> + return err;
> +}
> +
> +static int f2fs_ioc_defragment(struct file *filp, unsigned long arg)
> +{
> + struct inode *inode = file_inode(filp);
> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> + struct f2fs_defragment range;
> + int err;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + if (!S_ISREG(inode->i_mode))
> + return -EINVAL;
> +
> + err = mnt_want_write_file(filp);
> + if (err)
> + return err;
> +
> + if (f2fs_readonly(sbi->sb)) {
> + err = -EROFS;
> + goto out;
> + }
> +
> + if (copy_from_user(&range, (struct f2fs_defragment __user *)arg,
> + sizeof(range))) {
> + err = -EFAULT;
> + goto out;
> + }
> +
> + /* verify alignment of offset & size */
> + if (range.start & (F2FS_BLKSIZE - 1) ||
> + range.len & (F2FS_BLKSIZE - 1)) {
> + err = -EINVAL;
> + goto out;
> + }
> +
> + err = f2fs_defragment_range(sbi, filp, &range);
> + if (err < 0)
> + goto out;
> +
> + if (copy_to_user((struct f2fs_defragment __user *)arg, &range,
> + sizeof(range)))
> + err = -EFAULT;
> +out:
> + mnt_drop_write_file(filp);
> + return err;
> +}
> +
> long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> switch (cmd) {
> @@ -1679,6 +1877,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return f2fs_ioc_gc(filp, arg);
> case F2FS_IOC_WRITE_CHECKPOINT:
> return f2fs_ioc_write_checkpoint(filp, arg);
> + case F2FS_IOC_DEFRAGMENT:
> + return f2fs_ioc_defragment(filp, arg);
> default:
> return -ENOTTY;
> }
> --
> 2.6.1
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