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Message-ID: <8dbdca2c-0ef9-4e93-87ca-db275675017f@kernel.org>
Date: Thu, 15 Aug 2024 18:12:40 +0800
From: Chao Yu <chao@...nel.org>
To: Yeongjin Gil <youngjin.gil@...sung.com>, jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
Sungjong Seo <sj1557.seo@...sung.com>, Sunmin Jeong
<s_min.jeong@...sung.com>, Jaewook Kim <jw5454.kim@...sung.com>
Subject: Re: [PATCH] f2fs: compress: don't redirty sparse cluster during
{,de}compress
On 2024/8/13 14:11, Yeongjin Gil wrote:
> In f2fs_do_write_data_page, when the data block is NULL_ADDR, it skips
> writepage considering that it has been already truncated.
> This results in an infinite loop as the PAGECACHE_TAG_TOWRITE tag is not
> cleared during the writeback process for a compressed file including
> NULL_ADDR in compress_mode=user.
>
> This is the reproduction process:
>
> 1. dd if=/dev/zero bs=4096 count=1024 seek=1024 of=testfile
> 2. f2fs_io compress testfile
> 3. dd if=/dev/zero bs=4096 count=1 conv=notrunc of=testfile
> 4. f2fs_io decompress testfile
Good catch!
>
> To prevent the problem, let's check whether the cluster is fully
> allocated before redirty its pages.
>
> Reviewed-by: Sungjong Seo <sj1557.seo@...sung.com>
> Reviewed-by: Sunmin Jeong <s_min.jeong@...sung.com>
> Tested-by: Jaewook Kim <jw5454.kim@...sung.com>
> Signed-off-by: Yeongjin Gil <youngjin.gil@...sung.com>
Need a fixes line?
> ---
> fs/f2fs/compress.c | 34 ++++++++++++++++++++++++++--------
> fs/f2fs/f2fs.h | 12 ++++++++++++
> fs/f2fs/file.c | 39 +++++++++++++++++++++------------------
> 3 files changed, 59 insertions(+), 26 deletions(-)
>
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 990b93689b46..09b91d725807 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -945,7 +945,7 @@ static int __f2fs_get_cluster_blocks(struct inode *inode,
> unsigned int cluster_size = F2FS_I(inode)->i_cluster_size;
> int count, i;
>
> - for (i = 1, count = 1; i < cluster_size; i++) {
> + for (i = 0, count = 0; i < cluster_size; i++) {
> block_t blkaddr = data_blkaddr(dn->inode, dn->node_page,
> dn->ofs_in_node + i);
>
> @@ -956,8 +956,8 @@ static int __f2fs_get_cluster_blocks(struct inode *inode,
> return count;
> }
>
> -static int __f2fs_cluster_blocks(struct inode *inode,
> - unsigned int cluster_idx, bool compr_blks)
> +static int __f2fs_cluster_blocks(struct inode *inode, unsigned int cluster_idx,
> + enum cluster_check_type type)
> {
> struct dnode_of_data dn;
> unsigned int start_idx = cluster_idx <<
> @@ -978,10 +978,12 @@ static int __f2fs_cluster_blocks(struct inode *inode,
> }
>
> if (dn.data_blkaddr == COMPRESS_ADDR) {
> - if (compr_blks)
> - ret = __f2fs_get_cluster_blocks(inode, &dn);
> - else
> + if (type == COMPR_BLKS)
> + ret = 1 + __f2fs_get_cluster_blocks(inode, &dn);
> + else if (type == COMPR_CLUSTER)
> ret = 1;
> + } else if (type == DECOMPR_BLKS) {
> + ret = __f2fs_get_cluster_blocks(inode, &dn);
> }
> fail:
> f2fs_put_dnode(&dn);
> @@ -991,7 +993,14 @@ static int __f2fs_cluster_blocks(struct inode *inode,
> /* return # of compressed blocks in compressed cluster */
> static int f2fs_compressed_blocks(struct compress_ctx *cc)
> {
> - return __f2fs_cluster_blocks(cc->inode, cc->cluster_idx, true);
> + return __f2fs_cluster_blocks(cc->inode, cc->cluster_idx, COMPR_BLKS);
> +}
> +
> +/* return # of raw blocks in non-compressed cluster */
> +static int f2fs_decompressed_blocks(struct inode *inode,
> + unsigned int cluster_idx)
> +{
> + return __f2fs_cluster_blocks(inode, cluster_idx, DECOMPR_BLKS);
> }
>
> /* return whether cluster is compressed one or not */
> @@ -999,7 +1008,16 @@ int f2fs_is_compressed_cluster(struct inode *inode, pgoff_t index)
> {
> return __f2fs_cluster_blocks(inode,
> index >> F2FS_I(inode)->i_log_cluster_size,
> - false);
> + COMPR_CLUSTER);
> +}
> +
> +/* return whether the cluster is filled with raw blocks */
> +bool f2fs_is_non_sparse_cluster(struct inode *inode, pgoff_t index)
f2fs_is_sparse_cluster()?
> +{
> + unsigned int cluster_idx = index >> F2FS_I(inode)->i_log_cluster_size;
> +
> + return f2fs_decompressed_blocks(inode, cluster_idx) ==
> + F2FS_I(inode)->i_cluster_size;
> }
>
> static bool cluster_may_compress(struct compress_ctx *cc)
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 51fd5063a69c..6f26c8cb8857 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4302,6 +4302,11 @@ static inline bool f2fs_meta_inode_gc_required(struct inode *inode)
> * compress.c
> */
> #ifdef CONFIG_F2FS_FS_COMPRESSION
> +enum cluster_check_type {
> + COMPR_CLUSTER,
> + COMPR_BLKS,
> + DECOMPR_BLKS
How about?
CLUSTER_IS_COMPR,
CLUSTER_COMPR_BLKS,
CLUSTER_RAW_BLKS
> +};
Can you please add some comments for these enums?
> bool f2fs_is_compressed_page(struct page *page);
> struct page *f2fs_compress_control_page(struct page *page);
> int f2fs_prepare_compress_overwrite(struct inode *inode,
> @@ -4328,6 +4333,7 @@ int f2fs_write_multi_pages(struct compress_ctx *cc,
> struct writeback_control *wbc,
> enum iostat_type io_type);
> int f2fs_is_compressed_cluster(struct inode *inode, pgoff_t index);
> +bool f2fs_is_non_sparse_cluster(struct inode *inode, pgoff_t index);
> void f2fs_update_read_extent_tree_range_compressed(struct inode *inode,
> pgoff_t fofs, block_t blkaddr,
> unsigned int llen, unsigned int c_len);
> @@ -4414,6 +4420,12 @@ static inline bool f2fs_load_compressed_page(struct f2fs_sb_info *sbi,
> static inline void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi,
> nid_t ino) { }
> #define inc_compr_inode_stat(inode) do { } while (0)
> +static inline int f2fs_is_compressed_cluster(
> + struct inode *inode,
> + pgoff_t index) { return 0; }
> +static inline bool f2fs_is_non_sparse_cluster(
> + struct inode *inode,
> + pgoff_t index) { return false; }
> static inline void f2fs_update_read_extent_tree_range_compressed(
> struct inode *inode,
> pgoff_t fofs, block_t blkaddr,
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 270c32e3385f..fba8b5f216f9 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4220,9 +4220,8 @@ static int f2fs_ioc_decompress_file(struct file *filp)
> 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 = fi->i_cluster_size;
> - int count, ret;
> + pgoff_t page_idx = 0, last_idx, cluster_idx;
> + int ret;
>
> if (!f2fs_sb_has_compression(sbi) ||
> F2FS_OPTION(sbi).compress_mode != COMPR_MODE_USER)
> @@ -4257,10 +4256,15 @@ static int f2fs_ioc_decompress_file(struct file *filp)
> goto out;
>
> last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
> + last_idx >>= fi->i_log_cluster_size;
> +
> + for (cluster_idx = 0; cluster_idx < last_idx; cluster_idx++) {
> + page_idx = cluster_idx << fi->i_log_cluster_size;
> +
> + if (!f2fs_is_compressed_cluster(inode, page_idx))
> + continue;
>
> - count = last_idx - page_idx;
> - while (count && count >= cluster_size) {
> - ret = redirty_blocks(inode, page_idx, cluster_size);
> + ret = redirty_blocks(inode, page_idx, fi->i_cluster_size);
> if (ret < 0)
> break;
>
> @@ -4270,9 +4274,6 @@ static int f2fs_ioc_decompress_file(struct file *filp)
> break;
> }
>
> - count -= cluster_size;
> - page_idx += cluster_size;
> -
> cond_resched();
> if (fatal_signal_pending(current)) {
> ret = -EINTR;
> @@ -4299,9 +4300,9 @@ static int f2fs_ioc_compress_file(struct file *filp)
> {
> 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;
> + struct f2fs_inode_info *fi = F2FS_I(inode);
> + pgoff_t page_idx = 0, last_idx, cluster_idx;
> + int ret;
>
> if (!f2fs_sb_has_compression(sbi) ||
> F2FS_OPTION(sbi).compress_mode != COMPR_MODE_USER)
> @@ -4335,10 +4336,15 @@ static int f2fs_ioc_compress_file(struct file *filp)
> set_inode_flag(inode, FI_ENABLE_COMPRESS);
>
> last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
> + last_idx >>= fi->i_log_cluster_size;
>
> - count = last_idx - page_idx;
> - while (count && count >= cluster_size) {
> - ret = redirty_blocks(inode, page_idx, cluster_size);
> + for (cluster_idx = 0; cluster_idx < last_idx; cluster_idx++) {
> + page_idx = cluster_idx << fi->i_log_cluster_size;
> +
> + if (!f2fs_is_non_sparse_cluster(inode, page_idx))
if (f2fs_is_sparse_cluster())
continue;
Thanks,
> + continue;
> +
> + ret = redirty_blocks(inode, page_idx, fi->i_cluster_size);
> if (ret < 0)
> break;
>
> @@ -4348,9 +4354,6 @@ static int f2fs_ioc_compress_file(struct file *filp)
> break;
> }
>
> - count -= cluster_size;
> - page_idx += cluster_size;
> -
> cond_resched();
> if (fatal_signal_pending(current)) {
> ret = -EINTR;
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