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    SubjectRe: [f2fs-dev] [PATCH 2/2] f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
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    Daeho,

    On 2020/11/26 14:35, Daeho Jeong wrote:
    > Chao,
    >
    >> A little bit wired, why not failing cluster_may_compress() for user mode, and
    >> let writepages write cluster as raw blocks, in-where we can update i_compr_blocks
    >> and global compr block stats correctly.
    >
    > For decompression ioctl, I've made f2fs_need_compress_data() return
    > "false" to prevent compression write, so we don't use
    > f2fs_write_compressed_pages() anymore in this case.
    > Because of this, I manually updated i_compr_blocks. Do you have any
    > suggestions on this?

    I meant, we can control condition to call into below stack, then i_compr_blocks
    can be updated correctly.

    - f2fs_ioc_decompress_file
    - writepages
    - f2fs_write_multi_pages
    - cluster_may_compress return false when ioc_decompress is in-process.
    - f2fs_write_raw_pages
    - f2fs_do_write_data_page
    - f2fs_i_compr_blocks_update

    Thanks,

    >
    > 2020년 11월 26일 (목) 오후 2:04, Daeho Jeong <daeho43@gmail.com>님이 작성:
    >>
    >> Eric,
    >>
    >> do_page_cache_ra() is defined in mm/internal.h for internal use
    >> between in mm, so we cannot use this one right now.
    >> So, I think we could use page_cache_ra_unbounded(), because we already
    >> check i_size boundary on our own.
    >> What do you think?
    >>
    >> 2020년 11월 24일 (화) 오후 12:05, Chao Yu <yuchao0@huawei.com>님이 작성:
    >>>
    >>> On 2020/11/23 11:17, Daeho Jeong wrote:
    >>>> From: Daeho Jeong <daehojeong@google.com>
    >>>>
    >>>> Added two ioctl to decompress/compress explicitly the compression
    >>>> enabled file in "compress_mode=user-based" mount option.
    >>>>
    >>>> Using these two ioctls, the users can make a control of compression
    >>>> and decompression of their files.
    >>>>
    >>>> Signed-off-by: Daeho Jeong <daehojeong@google.com>
    >>>> ---
    >>>> fs/f2fs/file.c | 181 +++++++++++++++++++++++++++++++++++++-
    >>>> include/uapi/linux/f2fs.h | 2 +
    >>>> 2 files changed, 182 insertions(+), 1 deletion(-)
    >>>>
    >>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
    >>>> index be8db06aca27..e8f142470e87 100644
    >>>> --- a/fs/f2fs/file.c
    >>>> +++ b/fs/f2fs/file.c
    >>>> @@ -4026,6 +4026,180 @@ static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
    >>>> return ret;
    >>>> }
    >>>>
    >>>> +static int redirty_blocks(struct inode *inode, pgoff_t page_idx, int len)
    >>>> +{
    >>>> + DEFINE_READAHEAD(ractl, NULL, inode->i_mapping, page_idx);
    >>>> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
    >>>> + struct address_space *mapping = inode->i_mapping;
    >>>> + struct page *page;
    >>>> + pgoff_t redirty_idx = page_idx;
    >>>> + int i, page_len = 0, ret = 0;
    >>>> +
    >>>> + page_cache_ra_unbounded(&ractl, len, 0);
    >>>> +
    >>>> + for (i = 0; i < len; i++, page_idx++) {
    >>>> + page = read_cache_page(mapping, page_idx, NULL, NULL);
    >>>> + if (IS_ERR(page)) {
    >>>> + ret = PTR_ERR(page);
    >>>> + f2fs_warn(sbi, "%s: inode (%lu) : page_index (%lu) "
    >>>> + "couldn't be read (errno:%d).\n",
    >>>> + __func__, inode->i_ino, page_idx, ret);
    >>>
    >>> This is a common error case during calling read_cache_page(), IMO, this looks
    >>> more like a debug log, so I prefer to print nothing here, or at least using
    >>> f2fs_debug() instead.
    >>>
    >>>> + break;
    >>>> + }
    >>>> + page_len++;
    >>>> + }
    >>>> +
    >>>> + for (i = 0; i < page_len; i++, redirty_idx++) {
    >>>> + page = find_lock_page(mapping, redirty_idx);
    >>>> + if (!page) {
    >>>> + ret = -ENOENT;
    >>>> + f2fs_warn(sbi, "%s: inode (%lu) : page_index (%lu) "
    >>>> + "couldn't be found (errno:%d).\n",
    >>>> + __func__, inode->i_ino, redirty_idx, ret);
    >>>
    >>> Ditto.
    >>>
    >>>> + }
    >>>> + set_page_dirty(page);
    >>>> + f2fs_put_page(page, 1);
    >>>> + f2fs_put_page(page, 0);
    >>>> + }
    >>>> +
    >>>> + return ret;
    >>>> +}
    >>>> +
    >>>> +static int f2fs_ioc_decompress_file(struct file *filp, unsigned long arg)
    >>>> +{
    >>>> + struct inode *inode = file_inode(filp);
    >>>> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
    >>>> + struct f2fs_inode_info *fi = F2FS_I(inode);
    >>>> + pgoff_t page_idx = 0, last_idx;
    >>>> + int cluster_size = F2FS_I(inode)->i_cluster_size;
    >>>> + int count, ret;
    >>>> +
    >>>> + if (!f2fs_sb_has_compression(sbi))
    >>>> + return -EOPNOTSUPP;
    >>>> +
    >>>> + if (!(filp->f_mode & FMODE_WRITE))
    >>>> + return -EBADF;
    >>>> +
    >>>> + if (!f2fs_compressed_file(inode))
    >>>> + return -EINVAL;
    >>>
    >>> Before compressubg/decompressing file, should we check whether current inode's
    >>> compress algorithm backend is available in f2fs module?
    >>>
    >>>> +
    >>>> + f2fs_balance_fs(F2FS_I_SB(inode), true);
    >>>> +
    >>>> + file_start_write(filp);
    >>>> + inode_lock(inode);
    >>>> +
    >>>> + if (f2fs_is_mmap_file(inode)) {
    >>>> + ret = -EBUSY;
    >>>> + goto out;
    >>>> + }
    >>>> +
    >>>> + ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
    >>>> + if (ret)
    >>>> + goto out;
    >>>> +
    >>>> + if (!atomic_read(&fi->i_compr_blocks))
    >>>> + goto out;
    >>>> +
    >>>> + last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
    >>>> +
    >>>> + count = last_idx - page_idx;
    >>>> + while (count) {
    >>>> + int len = min(cluster_size, count);
    >>>> +
    >>>> + ret = redirty_blocks(inode, page_idx, len);
    >>>> +
    >>>
    >>> unneeded blank line..
    >>>
    >>>> + if (ret < 0)
    >>>> + break;
    >>>> +
    >>>> + page_idx += len;
    >>>> + count -= len;
    >>>
    >>> Considering there isn't so many memory in low-end device, how about calling
    >>> filemap_fdatawrite() to writeback cluster after redirty several clusters
    >>> or xxMB?
    >>>
    >>>> + }
    >>>> +
    >>>> + if (!ret)
    >>>> + ret = filemap_write_and_wait_range(inode->i_mapping, 0,
    >>>> + LLONG_MAX);
    >>>> +
    >>>> + if (!ret) {
    >>>> + stat_sub_compr_blocks(inode, atomic_read(&fi->i_compr_blocks));
    >>>> + atomic_set(&fi->i_compr_blocks, 0);
    >>>> + f2fs_mark_inode_dirty_sync(inode, true);
    >>>
    >>> A little bit wired, why not failing cluster_may_compress() for user mode, and
    >>> let writepages write cluster as raw blocks, in-where we can update i_compr_blocks
    >>> and global compr block stats correctly.
    >>>
    >>>> + } else {
    >>>> + f2fs_warn(sbi, "%s: The file might be partially decompressed "
    >>>> + "(errno=%d). Please delete the file.\n",
    >>>> + __func__, ret);
    >>>> + }
    >>>> +out:
    >>>> + inode_unlock(inode);
    >>>> + file_end_write(filp);
    >>>> +
    >>>> + return ret;
    >>>> +}
    >>>> +
    >>>> +static int f2fs_ioc_compress_file(struct file *filp, unsigned long arg)
    >>>> +{
    >>>> + struct inode *inode = file_inode(filp);
    >>>> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
    >>>> + pgoff_t page_idx = 0, last_idx;
    >>>> + int cluster_size = F2FS_I(inode)->i_cluster_size;
    >>>> + int count, ret;
    >>>> +
    >>>> + if (!f2fs_sb_has_compression(sbi))
    >>>> + return -EOPNOTSUPP;
    >>>> +
    >>>> + if (!(filp->f_mode & FMODE_WRITE))
    >>>> + return -EBADF;
    >>>> +
    >>>> + if (!f2fs_compressed_file(inode))
    >>>> + return -EINVAL;
    >>>
    >>> algorithm backend check?
    >>>
    >>>> +
    >>>> + f2fs_balance_fs(F2FS_I_SB(inode), true);
    >>>> +
    >>>> + file_start_write(filp);
    >>>> + inode_lock(inode);
    >>>> +
    >>>> + if (f2fs_is_mmap_file(inode)) {
    >>>> + ret = -EBUSY;
    >>>> + goto out;
    >>>> + }
    >>>> +
    >>>> + ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
    >>>> + if (ret)
    >>>> + goto out;
    >>>> +
    >>>> + set_inode_flag(inode, FI_ENABLE_COMPRESS);
    >>>> +
    >>>> + last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
    >>>> +
    >>>> + count = last_idx - page_idx;
    >>>> + while (count) {
    >>>> + int len = min(cluster_size, count);
    >>>> +
    >>>> + ret = redirty_blocks(inode, page_idx, len);
    >>>> +
    >>>
    >>> Ditto.
    >>>
    >>> Thanks,
    >>>
    >>>> + if (ret < 0)
    >>>> + break;
    >>>> +
    >>>> + page_idx += len;
    >>>> + count -= len;
    >>>> + }
    >>>> +
    >>>> + if (!ret)
    >>>> + ret = filemap_write_and_wait_range(inode->i_mapping, 0,
    >>>> + LLONG_MAX);
    >>>> +
    >>>> + clear_inode_flag(inode, FI_ENABLE_COMPRESS);
    >>>> +
    >>>> + if (ret)
    >>>> + f2fs_warn(sbi, "%s: The file might be partially compressed "
    >>>> + "(errno=%d). Please delete the file.\n",
    >>>> + __func__, ret);
    >>>> +out:
    >>>> + inode_unlock(inode);
    >>>> + file_end_write(filp);
    >>>> +
    >>>> + return ret;
    >>>> +}
    >>>> +
    >>>> static long __f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
    >>>> {
    >>>> switch (cmd) {
    >>>> @@ -4113,6 +4287,10 @@ static long __f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
    >>>> return f2fs_ioc_get_compress_option(filp, arg);
    >>>> case F2FS_IOC_SET_COMPRESS_OPTION:
    >>>> return f2fs_ioc_set_compress_option(filp, arg);
    >>>> + case F2FS_IOC_DECOMPRESS_FILE:
    >>>> + return f2fs_ioc_decompress_file(filp, arg);
    >>>> + case F2FS_IOC_COMPRESS_FILE:
    >>>> + return f2fs_ioc_compress_file(filp, arg);
    >>>> default:
    >>>> return -ENOTTY;
    >>>> }
    >>>> @@ -4352,7 +4530,8 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
    >>>> case F2FS_IOC_SEC_TRIM_FILE:
    >>>> case F2FS_IOC_GET_COMPRESS_OPTION:
    >>>> case F2FS_IOC_SET_COMPRESS_OPTION:
    >>>> - break;
    >>>> + case F2FS_IOC_DECOMPRESS_FILE:
    >>>> + case F2FS_IOC_COMPRESS_FILE:
    >>>> default:
    >>>> return -ENOIOCTLCMD;
    >>>> }
    >>>> diff --git a/include/uapi/linux/f2fs.h b/include/uapi/linux/f2fs.h
    >>>> index f00199a2e38b..352a822d4370 100644
    >>>> --- a/include/uapi/linux/f2fs.h
    >>>> +++ b/include/uapi/linux/f2fs.h
    >>>> @@ -40,6 +40,8 @@
    >>>> struct f2fs_comp_option)
    >>>> #define F2FS_IOC_SET_COMPRESS_OPTION _IOW(F2FS_IOCTL_MAGIC, 22, \
    >>>> struct f2fs_comp_option)
    >>>> +#define F2FS_IOC_DECOMPRESS_FILE _IO(F2FS_IOCTL_MAGIC, 23)
    >>>> +#define F2FS_IOC_COMPRESS_FILE _IO(F2FS_IOCTL_MAGIC, 24)
    >>>>
    >>>> /*
    >>>> * should be same as XFS_IOC_GOINGDOWN.
    >>>>
    > .
    >

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