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Message-ID: <20200224214605.GA77839@google.com>
Date: Mon, 24 Feb 2020 13:46:05 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [RFC PATCH 2/2] f2fs: introduce F2FS_IOC_RELEASE_COMPRESS_BLOCKS
On 02/21, Chao Yu wrote:
> There are still reserved blocks on compressed inode, this patch
> introduce a new ioctl to help release reserved blocks back to
> filesystem, so that userspace can reuse those freed space.
I thought we can add compressed_blocks into free space, after converting
the file to immutable one. Otherwise, this patch is able to corrupt the
filesystem very easily.
>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> fs/f2fs/f2fs.h | 6 +++
> fs/f2fs/file.c | 129 ++++++++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 134 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 15199df5d40a..468f807fd917 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -427,6 +427,8 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
> #define F2FS_IOC_PRECACHE_EXTENTS _IO(F2FS_IOCTL_MAGIC, 15)
> #define F2FS_IOC_RESIZE_FS _IOW(F2FS_IOCTL_MAGIC, 16, __u64)
> #define F2FS_IOC_GET_COMPRESS_BLOCKS _IOR(F2FS_IOCTL_MAGIC, 17, __u64)
> +#define F2FS_IOC_RELEASE_COMPRESS_BLOCKS \
> + _IOR(F2FS_IOCTL_MAGIC, 18, __u64)
>
> #define F2FS_IOC_GET_VOLUME_NAME FS_IOC_GETFSLABEL
> #define F2FS_IOC_SET_VOLUME_NAME FS_IOC_SETFSLABEL
> @@ -3957,6 +3959,10 @@ static inline void f2fs_i_compr_blocks_update(struct inode *inode,
> {
> int diff = F2FS_I(inode)->i_cluster_size - blocks;
>
> + /* don't update i_compr_blocks if saved blocks were released */
> + if (!add && !F2FS_I(inode)->i_compr_blocks)
> + return;
> +
> if (add) {
> F2FS_I(inode)->i_compr_blocks += diff;
> stat_add_compr_blocks(inode, diff);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 235708c892af..613f87151d90 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -557,6 +557,7 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
> bool compressed_cluster = false;
> int cluster_index = 0, valid_blocks = 0;
> int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
> + bool released = !F2FS_I(dn->inode)->i_compr_blocks;
>
> if (IS_INODE(dn->node_page) && f2fs_has_extra_attr(dn->inode))
> base = get_extra_isize(dn->inode);
> @@ -595,7 +596,9 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
> clear_inode_flag(dn->inode, FI_FIRST_BLOCK_WRITTEN);
>
> f2fs_invalidate_blocks(sbi, blkaddr);
> - nr_free++;
> +
> + if (released && blkaddr != COMPRESS_ADDR)
> + nr_free++;
> }
>
> if (compressed_cluster)
> @@ -3416,6 +3419,127 @@ static int f2fs_get_compress_blocks(struct file *filp, unsigned long arg)
> return put_user(blocks, (u64 __user *)arg);
> }
>
> +static int release_compress_blocks(struct dnode_of_data *dn, pgoff_t count)
> +{
> + struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
> + unsigned int released_blocks = 0;
> + int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
> +
> + while (count) {
> + int compr_blocks = 0;
> + block_t blkaddr = f2fs_data_blkaddr(dn);
> + int i;
> +
> + if (blkaddr != COMPRESS_ADDR) {
> + dn->ofs_in_node += cluster_size;
> + goto next;
> + }
> +
> + for (i = 0; i < cluster_size; i++, dn->ofs_in_node++) {
> + blkaddr = f2fs_data_blkaddr(dn);
> +
> + if (__is_valid_data_blkaddr(blkaddr)) {
> + compr_blocks++;
> + if (unlikely(!f2fs_is_valid_blkaddr(sbi, blkaddr,
> + DATA_GENERIC_ENHANCE)))
> + return -EFSCORRUPTED;
> + }
> +
> + if (blkaddr != NEW_ADDR)
> + continue;
> +
> + dn->data_blkaddr = NULL_ADDR;
> + f2fs_set_data_blkaddr(dn);
> + }
> +
> + f2fs_i_compr_blocks_update(dn->inode, compr_blocks, false);
> + dec_valid_block_count(sbi, dn->inode,
> + cluster_size - compr_blocks);
> +
> + released_blocks += cluster_size - compr_blocks;
> +next:
> + count -= cluster_size;
> + }
> +
> + return released_blocks;
> +}
> +
> +static int f2fs_release_compress_blocks(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;
> + unsigned int released_blocks = 0;
> + int ret;
> +
> + if (!f2fs_sb_has_compression(F2FS_I_SB(inode)))
> + return -EOPNOTSUPP;
> +
> + if (!f2fs_compressed_file(inode))
> + return -EINVAL;
> +
> + if (f2fs_readonly(sbi->sb))
> + return -EROFS;
> +
> + ret = mnt_want_write_file(filp);
> + if (ret)
> + return ret;
> +
> + if (!F2FS_I(inode)->i_compr_blocks)
> + goto out;
> +
> + f2fs_balance_fs(F2FS_I_SB(inode), true);
> +
> + inode_lock(inode);
> +
> + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> + down_write(&F2FS_I(inode)->i_mmap_sem);
> +
> + last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
> +
> + while (page_idx < last_idx) {
> + struct dnode_of_data dn;
> + pgoff_t end_offset, count;
> +
> + set_new_dnode(&dn, inode, NULL, NULL, 0);
> + ret = f2fs_get_dnode_of_data(&dn, page_idx, LOOKUP_NODE);
> + if (ret) {
> + if (ret == -ENOENT) {
> + page_idx = f2fs_get_next_page_offset(&dn,
> + page_idx);
> + ret = 0;
> + continue;
> + }
> + break;
> + }
> +
> + end_offset = ADDRS_PER_PAGE(dn.node_page, inode);
> + count = min(end_offset - dn.ofs_in_node, last_idx - page_idx);
> +
> + ret = release_compress_blocks(&dn, count);
> +
> + f2fs_put_dnode(&dn);
> +
> + if (ret < 0)
> + break;
> +
> + page_idx += count;
> + released_blocks += ret;
> + }
> +
> + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> +
> + inode_unlock(inode);
> +out:
> + mnt_drop_write_file(filp);
> +
> + if (!ret)
> + ret = put_user(released_blocks, (u64 __user *)arg);
> +
> + return ret;
> +}
> +
> long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
> @@ -3496,6 +3620,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return f2fs_set_volume_name(filp, arg);
> case F2FS_IOC_GET_COMPRESS_BLOCKS:
> return f2fs_get_compress_blocks(filp, arg);
> + case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
> + return f2fs_release_compress_blocks(filp, arg);
> default:
> return -ENOTTY;
> }
> @@ -3654,6 +3780,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> case F2FS_IOC_GET_VOLUME_NAME:
> case F2FS_IOC_SET_VOLUME_NAME:
> case F2FS_IOC_GET_COMPRESS_BLOCKS:
> + case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
> break;
> default:
> return -ENOIOCTLCMD;
> --
> 2.18.0.rc1
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