Re: [f2fs-dev] [PATCH] f2fs: introduce device aliasing file

From: Daeho Jeong
Date: Fri Sep 20 2024 - 11:39:00 EST


On Thu, Sep 19, 2024 at 6:14 AM Chao Yu <chao@xxxxxxxxxx> wrote:
>
> On 2024/9/14 5:28, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@xxxxxxxxxx>
> >
> > F2FS should understand how the device aliasing file works and support
> > deleting the file after use. A device aliasing file can be created by
> > mkfs.f2fs tool and it can map the whole device with an extrent, not
> > using node blocks. The file space should be pinned and normally used for
> > read-only usages.
> >
> > Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
> > ---
> > fs/f2fs/data.c | 5 +++++
> > fs/f2fs/extent_cache.c | 10 ++++++++++
> > fs/f2fs/f2fs.h | 5 +++++
> > fs/f2fs/file.c | 36 ++++++++++++++++++++++++++++++++----
> > fs/f2fs/inode.c | 10 ++++++++--
> > fs/f2fs/sysfs.c | 2 ++
> > 6 files changed, 62 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 6457e5bca9c9..9ce92093ba1e 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -3423,6 +3423,11 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
> >
> > if (!f2fs_lookup_read_extent_cache_block(inode, index,
> > &dn.data_blkaddr)) {
> > + if (IS_DEVICE_ALIASING(inode)) {
> > + err = -ENODATA;
> > + goto out;
> > + }
> > +
> > if (locked) {
> > err = f2fs_reserve_block(&dn, index);
> > goto out;
> > diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> > index fd1fc06359ee..03883963b991 100644
> > --- a/fs/f2fs/extent_cache.c
> > +++ b/fs/f2fs/extent_cache.c
> > @@ -401,6 +401,11 @@ void f2fs_init_read_extent_tree(struct inode *inode, struct page *ipage)
> > if (atomic_read(&et->node_cnt) || !ei.len)
> > goto skip;
> >
> > + if (IS_DEVICE_ALIASING(inode)) {
> > + et->largest = ei;
> > + goto skip;
> > + }
> > +
> > en = __attach_extent_node(sbi, et, &ei, NULL,
> > &et->root.rb_root.rb_node, true);
> > if (en) {
> > @@ -463,6 +468,11 @@ static bool __lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
> > goto out;
> > }
> >
> > + if (IS_DEVICE_ALIASING(inode)) {
> > + ret = false;
> > + goto out;
> > + }
> > +
> > en = __lookup_extent_node(&et->root, et->cached_en, pgofs);
> > if (!en)
> > goto out;
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index ac19c61f0c3e..59179b9b3a83 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -208,6 +208,7 @@ struct f2fs_mount_info {
> > #define F2FS_FEATURE_CASEFOLD 0x00001000
> > #define F2FS_FEATURE_COMPRESSION 0x00002000
> > #define F2FS_FEATURE_RO 0x00004000
> > +#define F2FS_FEATURE_DEVICE_ALIAS 0x00008000
> >
> > #define __F2FS_HAS_FEATURE(raw_super, mask) \
> > ((raw_super->feature & cpu_to_le32(mask)) != 0)
> > @@ -3001,6 +3002,7 @@ static inline void f2fs_change_bit(unsigned int nr, char *addr)
> > #define F2FS_DIRSYNC_FL 0x00010000 /* dirsync behaviour (directories only) */
> > #define F2FS_PROJINHERIT_FL 0x20000000 /* Create with parents projid */
> > #define F2FS_CASEFOLD_FL 0x40000000 /* Casefolded file */
> > +#define F2FS_DEVICE_ALIAS_FL 0x80000000 /* File for aliasing a device */
> >
> > #define F2FS_QUOTA_DEFAULT_FL (F2FS_NOATIME_FL | F2FS_IMMUTABLE_FL)
> >
> > @@ -3016,6 +3018,8 @@ static inline void f2fs_change_bit(unsigned int nr, char *addr)
> > /* Flags that are appropriate for non-directories/regular files. */
> > #define F2FS_OTHER_FLMASK (F2FS_NODUMP_FL | F2FS_NOATIME_FL)
> >
> > +#define IS_DEVICE_ALIASING(inode) (F2FS_I(inode)->i_flags & F2FS_DEVICE_ALIAS_FL)
> > +
> > static inline __u32 f2fs_mask_flags(umode_t mode, __u32 flags)
> > {
> > if (S_ISDIR(mode))
> > @@ -4478,6 +4482,7 @@ F2FS_FEATURE_FUNCS(sb_chksum, SB_CHKSUM);
> > F2FS_FEATURE_FUNCS(casefold, CASEFOLD);
> > F2FS_FEATURE_FUNCS(compression, COMPRESSION);
> > F2FS_FEATURE_FUNCS(readonly, RO);
> > +F2FS_FEATURE_FUNCS(device_alias, DEVICE_ALIAS);
> >
> > #ifdef CONFIG_BLK_DEV_ZONED
> > static inline bool f2fs_blkz_is_seq(struct f2fs_sb_info *sbi, int devi,
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 168f08507004..0f4af6b303ff 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -727,6 +727,11 @@ int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock)
> >
> > trace_f2fs_truncate_blocks_enter(inode, from);
> >
> > + if (IS_DEVICE_ALIASING(inode) && from) {
> > + err = -EINVAL;
> > + goto out_err;
> > + }
> > +
> > free_from = (pgoff_t)F2FS_BLK_ALIGN(from);
> >
> > if (free_from >= max_file_blocks(inode))
> > @@ -741,6 +746,21 @@ int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock)
> > goto out;
> > }
> >
> > + if (IS_DEVICE_ALIASING(inode)) {
> > + struct extent_tree *et = F2FS_I(inode)->extent_tree[EX_READ];
> > + struct extent_info ei = et->largest;
> > + unsigned int i;
> > +
> > + for (i = 0; i < ei.len; i++)
> > + f2fs_invalidate_blocks(sbi, ei.blk + i);
> > +
> > + dec_valid_block_count(sbi, inode, ei.len);
> > + f2fs_update_time(sbi, REQ_TIME);
> > +
> > + f2fs_put_page(ipage, 1);
> > + goto out;
> > + }
> > +
> > if (f2fs_has_inline_data(inode)) {
> > f2fs_truncate_inline_inode(inode, ipage, from);
> > f2fs_put_page(ipage, 1);
> > @@ -776,7 +796,7 @@ int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock)
> > /* lastly zero out the first data page */
> > if (!err)
> > err = truncate_partial_data_page(inode, from, truncate_page);
> > -
> > +out_err:
> > trace_f2fs_truncate_blocks_exit(inode, err);
> > return err;
> > }
> > @@ -994,7 +1014,8 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> > return -EPERM;
> >
> > if ((attr->ia_valid & ATTR_SIZE)) {
> > - if (!f2fs_is_compress_backend_ready(inode))
> > + if (!f2fs_is_compress_backend_ready(inode) ||
> > + IS_DEVICE_ALIASING(inode))
> > return -EOPNOTSUPP;
> > if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED) &&
> > !IS_ALIGNED(attr->ia_size,
> > @@ -1855,7 +1876,7 @@ static long f2fs_fallocate(struct file *file, int mode,
> > return -EIO;
> > if (!f2fs_is_checkpoint_ready(F2FS_I_SB(inode)))
> > return -ENOSPC;
> > - if (!f2fs_is_compress_backend_ready(inode))
> > + if (!f2fs_is_compress_backend_ready(inode) || IS_DEVICE_ALIASING(inode))
> > return -EOPNOTSUPP;
> >
> > /* f2fs only support ->fallocate for regular file */
> > @@ -3264,6 +3285,9 @@ int f2fs_pin_file_control(struct inode *inode, bool inc)
> > struct f2fs_inode_info *fi = F2FS_I(inode);
> > struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> >
> > + if (IS_DEVICE_ALIASING(inode))
> > + return -EINVAL;
> > +
> > if (fi->i_gc_failures >= sbi->gc_pin_file_threshold) {
> > f2fs_warn(sbi, "%s: Enable GC = ino %lx after %x GC trials",
> > __func__, inode->i_ino, fi->i_gc_failures);
> > @@ -3294,6 +3318,9 @@ static int f2fs_ioc_set_pin_file(struct file *filp, unsigned long arg)
> > if (f2fs_readonly(sbi->sb))
> > return -EROFS;
> >
> > + if (!pin && IS_DEVICE_ALIASING(inode))
> > + return -EOPNOTSUPP;
> > +
> > ret = mnt_want_write_file(filp);
> > if (ret)
> > return ret;
> > @@ -4711,7 +4738,8 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter,
> > else
> > return 0;
> >
> > - map.m_may_create = true;
> > + if (!IS_DEVICE_ALIASING(inode))
> > + map.m_may_create = true;
> > if (dio) {
> > map.m_seg_type = f2fs_rw_hint_to_seg_type(sbi,
> > inode->i_write_hint);
> > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> > index aef57172014f..f118e955ba88 100644
> > --- a/fs/f2fs/inode.c
> > +++ b/fs/f2fs/inode.c
> > @@ -367,6 +367,12 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page)
> > return false;
> > }
> >
> > + if ((fi->i_flags & F2FS_DEVICE_ALIAS_FL) && !f2fs_sb_has_device_alias(sbi)) {
> > + f2fs_warn(sbi, "%s: inode (ino=%lx) has device alias flag, but the feature is off",
> > + __func__, inode->i_ino);
> > + return false;
> > + }
>
> Do we need to do sanity check device_alias feature flag w/
> sb.devs[].path format? and related inode?

Sorry, I am not sure I got your point. Could you elaborate it more?

>
> > +
> > return true;
> > }
> >
> > @@ -818,8 +824,6 @@ void f2fs_evict_inode(struct inode *inode)
> > f2fs_bug_on(sbi, get_dirty_pages(inode));
> > f2fs_remove_dirty_inode(inode);
> >
> > - f2fs_destroy_extent_tree(inode);
>
> For hardlink inode, it missed to call f2fs_destroy_extent_tree()?

Got it.

>
> Thanks,
>
> > -
> > if (inode->i_nlink || is_bad_inode(inode))
> > goto no_delete;
> >
> > @@ -874,6 +878,8 @@ void f2fs_evict_inode(struct inode *inode)
> > goto retry;
> > }
> >
> > + f2fs_destroy_extent_tree(inode);
> > +
> > if (err) {
> > f2fs_update_inode_page(inode);
> > if (dquot_initialize_needed(inode))
> > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> > index fee7ee45ceaa..bf64f4cc3522 100644
> > --- a/fs/f2fs/sysfs.c
> > +++ b/fs/f2fs/sysfs.c
> > @@ -1281,6 +1281,7 @@ F2FS_SB_FEATURE_RO_ATTR(sb_checksum, SB_CHKSUM);
> > F2FS_SB_FEATURE_RO_ATTR(casefold, CASEFOLD);
> > F2FS_SB_FEATURE_RO_ATTR(compression, COMPRESSION);
> > F2FS_SB_FEATURE_RO_ATTR(readonly, RO);
> > +F2FS_SB_FEATURE_RO_ATTR(device_alias, DEVICE_ALIAS);
> >
> > static struct attribute *f2fs_sb_feat_attrs[] = {
> > ATTR_LIST(sb_encryption),
> > @@ -1297,6 +1298,7 @@ static struct attribute *f2fs_sb_feat_attrs[] = {
> > ATTR_LIST(sb_casefold),
> > ATTR_LIST(sb_compression),
> > ATTR_LIST(sb_readonly),
> > + ATTR_LIST(sb_device_alias),
> > NULL,
> > };
> > ATTRIBUTE_GROUPS(f2fs_sb_feat);
>