Re: [f2fs-dev] [PATCH v4] f2fs: support dynamic reserve/release for device aliasing

Daeho Jeong <[email protected]> Thu, 23 Jul 2026 08:08:56 -0700
Newsgroups net.sourceforge.lists.linux-f2fs-devel,org.kernel.vger.linux-kernel
Message-ID <CACOAw_xrZu3WP-M+mLV89ag8_DqoN3+uT3peP+pf4i7FF6QoFA@mail.gmail.com>
On Wed, Jul 22, 2026 at 5:23 AM Chao Yu <[email protected]> wrote:
>
> On 7/22/26 01:53, Daeho Jeong wrote:
> > On Sun, Jul 19, 2026 at 1:54 AM Chao Yu <[email protected]> wrote:
> >>
> >> On 7/14/26 00:05, Daeho Jeong wrote:
> >>> From: Daeho Jeong <[email protected]>
> >>>
> >>> This patch adds a dynamic management feature to the existing device
> >>> aliasing functionality. It allows users to dynamically reserve or
> >>> release specific devices from the filesystem's free pool at runtime
> >>> through new ioctls.
> >>>
> >>> To support this, three new ioctls are introduced:
> >>> - F2FS_IOC_RESERVE_DEV_ALIAS: This reclaims the space occupied by a
> >>>    device aliasing file. It first performs a capacity check, resets GC
> >>>    victim information for the target range, marks the segments as in-use
> >>>    to prevent new allocations, and then triggers GC to migrate existing
> >>>    valid data out of the range. Finally, it reserves these blocks in the
> >>>    SIT to effectively exclude the device from the usable capacity.
> >>>
> >>> - F2FS_IOC_RELEASE_DEV_ALIAS: This releases the reserved space of a
> >>>    previously reserved device aliasing file. It truncates the blocks
> >>>    associated with the file, which makes them available for general
> >>>    filesystem allocation again.
> >>>
> >>> - F2FS_IOC_GET_DEV_ALIAS_STATUS: This retrieves the current aliasing
> >>>    status of a device aliasing file, returning whether the file is
> >>>    released (inactive alias) or reserved (active alias, with blocks
> >>>    fully allocated on the device).
> >>>
> >>> Signed-off-by: Daeho Jeong <[email protected]>
> >>> ---
> >>> v4: renamed interfaces.
> >>>      fixed race conditions between checkpoint=disable mount and ioctls.
> >>>      refactored segment reservation part.
> >>>      modified lock usage.
> >>> v3: add CAP_SYS_ADMIN and checkpoint=disabled check.
> >>>      remove a f2fs specific flag exposed with getflags.
> >>> v2: prevent operations during checkpoint=disabled.
> >>> ---
> >>>   Documentation/filesystems/f2fs.rst |  35 ++++
> >>>   fs/f2fs/f2fs.h                     |   9 +-
> >>>   fs/f2fs/file.c                     | 289 ++++++++++++++++++++++++++++-
> >>>   fs/f2fs/gc.c                       |  30 +--
> >>>   fs/f2fs/namei.c                    |  14 ++
> >>>   fs/f2fs/segment.c                  | 180 +++++++++++++-----
> >>>   fs/f2fs/segment.h                  |  26 +++
> >>>   fs/f2fs/super.c                    |  34 ++++
> >>>   include/uapi/linux/f2fs.h          |   7 +
> >>>   9 files changed, 562 insertions(+), 62 deletions(-)
> >>>
> >>> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> >>> index 8c4a14ae444f..1a5fd4afe609 100644
> >>> --- a/Documentation/filesystems/f2fs.rst
> >>> +++ b/Documentation/filesystems/f2fs.rst
> >>> @@ -1045,6 +1045,41 @@ So, the key idea is, user can do any file operations on /dev/vdc, and
> >>>   reclaim the space after the use, while the space is counted as /data.
> >>>   That doesn't require modifying partition size and filesystem format.
> >>>
> >>> +Dynamic Device Aliasing Management
> >>> +----------------------------------
> >>> +
> >>> +In addition to static device aliasing by deleting the aliasing file, F2FS
> >>> +supports dynamic management of device aliasing. This mechanism allows the system
> >>> +to dynamically transition partition ownership between F2FS userdata and external
> >>> +entities (e.g., zRAM, raw partition) based on system requirements without
> >>> +deleting the master aliasing file or requiring unmount/remount.
> >>> +
> >>> +The master aliasing file is created during the initial format of the file system
> >>> +and remains as a persistent control entity (ioctl gateway) in the root directory.
> >>> +
> >>> +- Partition Reservation (In-service to Aliased)
> >>> +  When a specific partition needs to be dedicated to external services (e.g., zRAM),
> >>> +  a user can reserve the device alias range via ioctl. The kernel resets GC victim
> >>> +  information for the target range, marks segments as in-use to prevent new
> >>> +  allocations, and triggers forced GC to migrate existing valid data out of the
> >>> +  range. Finally, it reserves these blocks in the SIT to effectively exclude the
> >>> +  device from the usable capacity.
> >>> +
> >>> +- Partition Release (Aliased to In-service)
> >>> +  When external usage concludes, the space is reclaimed not by deleting the file,
> >>> +  but through the release ioctl. The kernel truncates blocks associated with
> >>> +  the file, releasing them back to general filesystem allocation.
> >>> +
> >>> +.. code-block::
> >>> +
> >>> +   # f2fs_io dev_alias release /mnt/f2fs/vdc.file
> >>> +   # df -h
> >>> +   /dev/vdb                            64G  753M   64G   2% /mnt/f2fs
> >>> +
> >>> +   # f2fs_io dev_alias reserve /mnt/f2fs/vdc.file
> >>> +   # df -h
> >>> +   /dev/vdb                            64G   33G   32G  52% /mnt/f2fs
> >>> +
> >>>   Per-file Read-Only Large Folio Support
> >>>   --------------------------------------
> >>>
> >>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>> index f1774d4e18d2..0f9b8b66cef9 100644
> >>> --- a/fs/f2fs/f2fs.h
> >>> +++ b/fs/f2fs/f2fs.h
> >>> @@ -1404,6 +1404,8 @@ struct f2fs_dev_info {
> >>>       unsigned int total_segments;
> >>>       block_t start_blk;
> >>>       block_t end_blk;
> >>> +     bool has_alias;
> >>> +     bool is_reserving;
> >>>   #ifdef CONFIG_BLK_DEV_ZONED
> >>>       unsigned int nr_blkz;           /* Total number of zones */
> >>>       unsigned long *blkz_seq;        /* Bitmap indicating sequential zones */
> >>> @@ -4009,7 +4011,10 @@ int f2fs_create_flush_cmd_control(struct f2fs_sb_info *sbi);
> >>>   int f2fs_flush_device_cache(struct f2fs_sb_info *sbi);
> >>>   void f2fs_destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free);
> >>>   void f2fs_invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr,
> >>> -                                             unsigned int len);
> >>> +                             unsigned int len);
> >>> +void f2fs_reserve_device_alias(struct f2fs_sb_info *sbi, block_t addr,
> >>> +                             unsigned int len);
> >>> +
> >>>   bool f2fs_is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr);
> >>>   int f2fs_start_discard_thread(struct f2fs_sb_info *sbi);
> >>>   void f2fs_drop_discard_cmd(struct f2fs_sb_info *sbi);
> >>> @@ -4231,6 +4236,8 @@ void f2fs_build_gc_manager(struct f2fs_sb_info *sbi);
> >>>   int f2fs_gc_range(struct f2fs_sb_info *sbi,
> >>>               unsigned int start_seg, unsigned int end_seg,
> >>>               bool dry_run, unsigned int dry_run_sections);
> >>> +void f2fs_reset_gc_victim_resource(struct f2fs_sb_info *sbi,
> >>> +             unsigned int start, unsigned int end);
> >>>   int f2fs_resize_fs(struct file *filp, __u64 block_count);
> >>>   int __init f2fs_create_garbage_collection_cache(void);
> >>>   void f2fs_destroy_garbage_collection_cache(void);
> >>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> >>> index 4b52c56d71f0..9077c091c2d6 100644
> >>> --- a/fs/f2fs/file.c
> >>> +++ b/fs/f2fs/file.c
> >>> @@ -813,13 +813,19 @@ int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock)
> >>>
> >>>       if (IS_DEVICE_ALIASING(inode)) {
> >>>               struct extent_tree *et = F2FS_I(inode)->extent_tree[EX_READ];
> >>> -             struct extent_info ei = et->largest;
> >>> +             struct extent_info ei;
> >>> +
> >>> +             read_lock(&et->lock);
> >>> +             ei = et->largest;
> >>> +             read_unlock(&et->lock);
> >>>
> >>>               f2fs_invalidate_blocks(sbi, ei.blk, ei.len);
> >>>
> >>>               dec_valid_block_count(sbi, inode, ei.len);
> >>>               f2fs_update_time(sbi, REQ_TIME);
> >>>
> >>> +             f2fs_drop_extent_tree(inode);
> >>> +
> >>>               f2fs_folio_put(ifolio, true);
> >>>               goto out;
> >>>       }
> >>> @@ -1100,8 +1106,9 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> >>>       if ((attr->ia_valid & ATTR_SIZE)) {
> >>>               if (mapping_large_folio_support(inode->i_mapping))
> >>>                       return -EOPNOTSUPP;
> >>> -             if (!f2fs_is_compress_backend_ready(inode) ||
> >>> -                             IS_DEVICE_ALIASING(inode))
> >>> +             if (IS_DEVICE_ALIASING(inode))
> >>> +                     return -EPERM;
> >>> +             if (!f2fs_is_compress_backend_ready(inode))
> >>>                       return -EOPNOTSUPP;
> >>>               if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED) &&
> >>>                       !IS_ALIGNED(attr->ia_size,
> >>> @@ -2130,6 +2137,9 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
> >>>       if (IS_NOQUOTA(inode))
> >>>               return -EPERM;
> >>>
> >>> +     if (IS_DEVICE_ALIASING(inode))
> >>> +             return -EPERM;
> >>> +
> >>>       if ((iflags ^ masked_flags) & F2FS_CASEFOLD_FL) {
> >>>               if (!f2fs_sb_has_casefold(F2FS_I_SB(inode)))
> >>>                       return -EOPNOTSUPP;
> >>> @@ -2678,6 +2688,17 @@ static int f2fs_ioc_get_encryption_policy(struct file *filp, unsigned long arg)
> >>>       return fscrypt_ioctl_get_policy(filp, (void __user *)arg);
> >>>   }
> >>>
> >>> +static int f2fs_ioc_get_dev_alias_status(struct file *filp, unsigned long arg)
> >>> +{
> >>> +     struct inode *inode = file_inode(filp);
> >>> +
> >>> +     if (!IS_DEVICE_ALIASING(inode))
> >>> +             return -EINVAL;
> >>> +
> >>> +     return put_user(F2FS_HAS_BLOCKS(inode) ? F2FS_DEV_ALIAS_STATUS_RESERVED :
> >>> +                             F2FS_DEV_ALIAS_STATUS_RELEASED, (u32 __user *)arg);
> >>> +}
> >>> +
> >>>   static int f2fs_ioc_get_encryption_pwsalt(struct file *filp, unsigned long arg)
> >>>   {
> >>>       struct inode *inode = file_inode(filp);
> >>> @@ -3616,6 +3637,259 @@ static int f2fs_ioc_get_dev_alias_file(struct file *filp, unsigned long arg)
> >>>                       (u32 __user *)arg);
> >>>   }
> >>>
> >>> +static int f2fs_ioc_reserve_dev_alias(struct file *filp)
> >>> +{
> >>> +     struct inode *inode = file_inode(filp);
> >>> +     struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> >>> +     struct extent_tree *et = F2FS_I(inode)->extent_tree[EX_READ];
> >>> +     struct extent_info ei;
> >>> +     struct cp_control cpc = { CP_SYNC, 0, 0, 0 };
> >>> +     struct f2fs_lock_context lc, glc;
> >>> +     blkcnt_t count;
> >>> +     unsigned int start, end, segno;
> >>> +     int type, i, err;
> >>> +
> >>> +     if (!capable(CAP_SYS_ADMIN))
> >>> +             return -EPERM;
> >>> +
> >>> +     if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
> >>> +             return -EINVAL;
> >>> +
> >>> +     err = mnt_want_write_file(filp);
> >>> +     if (err)
> >>> +             return err;
> >>> +
> >>> +     inode_lock(inode);
> >>> +
> >>> +     if (!IS_DEVICE_ALIASING(inode)) {
> >>> +             err = -EINVAL;
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     if (F2FS_HAS_BLOCKS(inode)) {
> >>> +             err = 0;
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     for (i = 1; i < sbi->s_ndevs; i++) {
> >>> +             char *name = strrchr(FDEV(i).path, '/');
> >>> +
> >>> +             name = name ? name + 1 : FDEV(i).path;
> >>> +             if (!strcmp(name, filp->f_path.dentry->d_name.name)) {
> >>> +                     ei.blk = FDEV(i).start_blk;
> >>> +                     ei.len = FDEV(i).total_segments << sbi->log_blocks_per_seg;
> >>> +                     ei.fofs = 0;
> >>> +                     break;
> >>> +             }
> >>> +     }
> >>> +
> >>> +     if (i == sbi->s_ndevs) {
> >>> +             f2fs_warn(sbi, "device alias file (%s, ino=%llu) has no matching device",
> >>> +                       filp->f_path.dentry->d_name.name, inode->i_ino);
> >>> +             set_sbi_flag(sbi, SBI_NEED_FSCK);
> >>> +             f2fs_handle_error(sbi, ERROR_CORRUPTED_INODE);
> >>> +             err = -EFSCORRUPTED;
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     f2fs_down_write_trace(&sbi->gc_lock, &glc);
> >>> +     f2fs_lock_op(sbi, &lc);
> >>> +
> >>> +     if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> >>> +             err = -EINVAL;
> >>> +     } else {
> >>> +             count = ei.len;
> >>> +             err = inc_valid_block_count(sbi, inode, &count, false);
> >>> +     }
> >>> +     if (err) {
> >>> +             f2fs_unlock_op(sbi, &lc);
> >>> +             f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     spin_lock(&FREE_I(sbi)->segmap_lock);
> >>> +     FDEV(f2fs_target_device_index(sbi, ei.blk)).is_reserving = true;
> >>> +     spin_unlock(&FREE_I(sbi)->segmap_lock);
> >>> +
> >>> +     start = GET_SEGNO(sbi, ei.blk);
> >>> +     end = GET_SEGNO(sbi, ei.blk + ei.len - 1);
> >>> +
> >>> +     /* Reset the victim information to prevent GC from targeting the range */
> >>> +     f2fs_reset_gc_victim_resource(sbi, start, end);
> >>> +
> >>> +     /* Move out cursegs from the target range */
> >>> +     for (type = CURSEG_HOT_DATA; type < NR_CURSEG_PERSIST_TYPE; type++) {
> >>> +             err = f2fs_allocate_segment_for_resize(sbi, type, start, end);
> >>> +             if (err) {
> >>> +                     f2fs_unlock_op(sbi, &lc);
> >>> +                     goto out_gc_unlock;
> >>> +             }
> >>> +     }
> >>> +
> >>> +     f2fs_unlock_op(sbi, &lc);
> >>> +     f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>> +
> >>> +     /* Write checkpoint synchronously to flush all pending writes and free space */
> >>> +     err = f2fs_write_checkpoint(sbi, &cpc);
> >>> +     if (err) {
> >>> +             f2fs_down_write_trace(&sbi->gc_lock, &glc);
> >>> +             goto out_gc_unlock;
> >>> +     }
>
>           ^^^
>
> I meant we have reserved blocks via inc_valid_block_count(), then here we trigger
> a checkpoint, if it shutdowns later, device alias file may only have reserved
> blocks w/o any physical blocks? IIUC.

Yes, right. I got your point.
Thanks~!

>
> >>> +
> >>> +     /* Re-acquire gc_lock and cp_rwsem read lock for the entire range GC */
> >>> +     f2fs_down_write_trace(&sbi->gc_lock, &glc);
> >>> +     f2fs_lock_op(sbi, &lc);
> >>> +
> >>> +     if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> >>> +             err = -EINVAL;
> >>> +             f2fs_unlock_op(sbi, &lc);
> >>> +             goto out_gc_unlock;
> >>> +     }
> >>> +
> >>> +     /* do GC to move out valid blocks in the range all at once! */
> >>> +     err = f2fs_gc_range(sbi, start, end, false, 0);
> >>> +     if (err) {
> >>> +             f2fs_unlock_op(sbi, &lc);
> >>> +             goto out_gc_unlock;
> >>> +     }
> >>> +
> >>> +     if (et) {
> >>> +             write_lock(&et->lock);
> >>> +             et->largest = ei;
> >>> +             write_unlock(&et->lock);
> >>> +     }
> >>> +     clear_inode_flag(inode, FI_NO_EXTENT);
> >>> +
> >>> +     f2fs_reserve_device_alias(sbi, ei.blk, ei.len);
> >>> +
> >>> +     i_size_write(inode, (loff_t)ei.len << PAGE_SHIFT);
> >>> +     f2fs_update_inode_page(inode);
> >>> +
> >>> +     spin_lock(&FREE_I(sbi)->segmap_lock);
> >>> +     FDEV(f2fs_target_device_index(sbi, ei.blk)).is_reserving = false;
> >>> +     spin_unlock(&FREE_I(sbi)->segmap_lock);
> >>> +
> >>> +     f2fs_unlock_op(sbi, &lc);
> >>> +     f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>> +
> >>> +     inode_unlock(inode);
> >>> +     mnt_drop_write_file(filp);
> >>> +
> >>> +     err = f2fs_write_checkpoint(sbi, &cpc);
> >>> +     return err;
> >>> +
> >>> +out_gc_unlock:
> >>> +     spin_lock(&FREE_I(sbi)->segmap_lock);
> >>> +     FDEV(f2fs_target_device_index(sbi, ei.blk)).is_reserving = false;
> >>> +     spin_unlock(&FREE_I(sbi)->segmap_lock);
> >>> +     f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>
> >> Seems, once we have reserved blocks above, and then unlock cp_rwsem and
> >> gc_lock, a following CP and sudden power-cut recovery will make device alias
> >> file corrupted?
> >
> >
> > Could you please elaborate on the specific scenario or race condition
> > you are concerned about?
>
> Please check above comments.
>
> >
> > In the current implementation:
> >  - Both the SIT entry updates (f2fs_reserve_device_alias) and the
> > inode page updates (f2fs_update_inode_page) are performed under
> > cp_rwsem (f2fs_lock_op).
> >  - Once cp_rwsem is unlocked, both dirty SIT entries and the dirty
> > inode page will be committed together atomically by any following
> > Checkpoint.
> >  - If a sudden power-cut happens before the final Checkpoint
> > completes, the filesystem safely recovers to the prior Checkpoint
> > (where the alias file remains in the released/unreserved state with
> > i_size = 0). If it happens after, it recovers to the new Checkpoint
> > (where the alias file is fully reserved).
> >
> > Is there a specific edge case or inconsistency during recovery that I
> > might have missed?
> >
> >>
> >>
> >> Maybe we can reserve blocks for device alias file w/ in-memory variable, something
> >> like reserve_root?
> >>
> >>> +
> >>> +     /*
> >>> +      * Put successfully GC'ed segments back into PRE list so checkpoint
> >>> +      * commits and frees them!
> >>> +      */
> >>
> >> I didn't get it, why do we need to set empty segment as prefree one? You mean
> >> f2fs_reserve_device_alias() has removed all prefreed segments? seems after
> >> f2fs_reserve_device_alias() there is no error path.
> >
> > You are completely right.
> > f2fs_reserve_device_alias() is only called on the success path, so
> > prefreed segments are never removed from the PRE list on the error
> > path (out_gc_unlock).
> > Furthermore, f2fs_gc_range() already handles tracking invalidated
> > segments in the PRE list automatically through standard block
> > invalidation.
> > Therefore, this manual loop adding segments back to dirty_segmap[PRE]
> > in out_gc_unlock is redundant. I will remove this logic in the next
> > version.
> >
> > Thank you for catching this!
> >
> >>
> >>> +     f2fs_lock_op(sbi, &lc);
> >>> +     for (segno = start; segno <= end; segno++) {
> >>> +             if (get_valid_blocks(sbi, segno, false) == 0) {
> >>> +                     mutex_lock(&DIRTY_I(sbi)->seglist_lock);
> >>> +                     if (!test_and_set_bit(segno, DIRTY_I(sbi)->dirty_segmap[PRE]))
> >>> +                             DIRTY_I(sbi)->nr_dirty[PRE]++;
> >>> +                     mutex_unlock(&DIRTY_I(sbi)->seglist_lock);
> >>> +             }
> >>> +     }
> >>> +     count = ei.len;
> >>> +     dec_valid_block_count(sbi, inode, count);
> >>> +     f2fs_unlock_op(sbi, &lc);
> >>> +
> >>> +     inode_unlock(inode);
> >>> +     mnt_drop_write_file(filp);
> >>> +
> >>> +     f2fs_write_checkpoint(sbi, &cpc);
> >>> +     return err;
> >>> +
> >>> +out_inode_unlock:
> >>> +     inode_unlock(inode);
> >>> +     mnt_drop_write_file(filp);
> >>> +     return err;
> >>> +}
> >>> +
> >>> +static int f2fs_ioc_release_dev_alias(struct file *filp)
> >>> +{
> >>> +     struct inode *inode = file_inode(filp);
> >>> +     struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> >>> +     struct extent_tree *et = F2FS_I(inode)->extent_tree[EX_READ];
> >>> +     struct extent_info ei = {0, };
> >>> +     struct cp_control cpc = { CP_SYNC, 0, 0, 0 };
> >>> +     struct f2fs_lock_context lc, glc;
> >>> +     int err;
> >>> +
> >>> +     if (!capable(CAP_SYS_ADMIN))
> >>> +             return -EPERM;
> >>> +
> >>> +     if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
> >>> +             return -EINVAL;
> >>> +
> >>> +     err = mnt_want_write_file(filp);
> >>> +     if (err)
> >>> +             return err;
> >>> +
> >>> +     inode_lock(inode);
> >>> +
> >>> +     if (!IS_DEVICE_ALIASING(inode)) {
> >>> +             err = -EINVAL;
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     if (!F2FS_HAS_BLOCKS(inode)) {
> >>> +             err = 0;
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     err = filemap_write_and_wait(inode->i_mapping);
> >>> +     if (err)
> >>> +             goto out_inode_unlock;
> >>> +
> >>> +     read_lock(&et->lock);
> >>> +     ei = et->largest;
> >>> +     read_unlock(&et->lock);
> >>> +
> >>> +     f2fs_down_write_trace(&sbi->gc_lock, &glc);
> >>> +     f2fs_lock_op(sbi, &lc);
> >>> +
> >>> +     if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> >>> +             err = -EINVAL;
> >>> +             f2fs_unlock_op(sbi, &lc);
> >>> +             f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     truncate_setsize(inode, 0);
> >>> +
> >>> +     err = f2fs_truncate_blocks(inode, 0, false);
> >>> +     if (err) {
> >>> +             i_size_write(inode, (loff_t)ei.len << PAGE_SHIFT);
> >>
> >> If f2fs_truncate_blocks() partially truncated blocks of device alias file,
> >> it will be corrupted, since a pinned file may has partial valid blocks in
> >> section?
> >>
> >> Can fsck detect such status of device alias for repair?
> >>
> >
> > That's a great question, but for device alias files, block truncation
> > is strictly an all-or-nothing operation.
> >
> > As implemented in f2fs_truncate_blocks() (file.c:814):
> >
> > For IS_DEVICE_ALIASING(inode), we do not iterate over dnodes or
> > truncate blocks partially. Instead, all ei.len blocks are invalidated
> > at once in a single call via f2fs_invalidate_blocks(sbi, ei.blk,
> > ei.len).
> > The only error paths in f2fs_truncate_blocks() occur before
> > f2fs_invalidate_blocks() is called, when zero blocks have been
> > invalidated.
> > Once f2fs_invalidate_blocks() is reached, all blocks are invalidated
> > together and the function succeeds.
> >
> > Therefore, partial block truncation never happens for device alias files:
> >
> > If f2fs_truncate_blocks() fails, 0 blocks have been freed, so
> > restoring i_size safely preserves the fully-reserved file without any
> > holes.
> > If it succeeds, 100% of the blocks are freed.
>
> Oh, that's right, thanks for the explaination.
>
> Thanks,
>
> >
> >> Thanks,
> >>
> >>> +             f2fs_unlock_op(sbi, &lc);
> >>> +             f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>> +             goto out_inode_unlock;
> >>> +     }
> >>> +
> >>> +     f2fs_update_inode_page(inode);
> >>> +
> >>> +     f2fs_unlock_op(sbi, &lc);
> >>> +     f2fs_up_write_trace(&sbi->gc_lock, &glc);
> >>> +
> >>> +     inode_unlock(inode);
> >>> +     mnt_drop_write_file(filp);
> >>> +
> >>> +     err = f2fs_write_checkpoint(sbi, &cpc);
> >>> +     return err;
> >>> +
> >>> +out_inode_unlock:
> >>> +     inode_unlock(inode);
> >>> +     mnt_drop_write_file(filp);
> >>> +     return err;
> >>> +}
> >>> +
> >>>   static int f2fs_ioc_io_prio(struct file *filp, unsigned long arg)
> >>>   {
> >>>       struct inode *inode = file_inode(filp);
> >>> @@ -4742,8 +5016,14 @@ static long __f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> >>>               return f2fs_ioc_compress_file(filp);
> >>>       case F2FS_IOC_GET_DEV_ALIAS_FILE:
> >>>               return f2fs_ioc_get_dev_alias_file(filp, arg);
> >>> +     case F2FS_IOC_GET_DEV_ALIAS_STATUS:
> >>> +             return f2fs_ioc_get_dev_alias_status(filp, arg);
> >>>       case F2FS_IOC_IO_PRIO:
> >>>               return f2fs_ioc_io_prio(filp, arg);
> >>> +     case F2FS_IOC_RESERVE_DEV_ALIAS:
> >>> +             return f2fs_ioc_reserve_dev_alias(filp);
> >>> +     case F2FS_IOC_RELEASE_DEV_ALIAS:
> >>> +             return f2fs_ioc_release_dev_alias(filp);
> >>>       default:
> >>>               return -ENOTTY;
> >>>       }
> >>> @@ -5530,7 +5810,10 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> >>>       case F2FS_IOC_DECOMPRESS_FILE:
> >>>       case F2FS_IOC_COMPRESS_FILE:
> >>>       case F2FS_IOC_GET_DEV_ALIAS_FILE:
> >>> +     case F2FS_IOC_GET_DEV_ALIAS_STATUS:
> >>>       case F2FS_IOC_IO_PRIO:
> >>> +     case F2FS_IOC_RESERVE_DEV_ALIAS:
> >>> +     case F2FS_IOC_RELEASE_DEV_ALIAS:
> >>>               break;
> >>>       default:
> >>>               return -ENOIOCTLCMD;
> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>> index ffaa7ba76a1b..93bcb35a5b5d 100644
> >>> --- a/fs/f2fs/gc.c
> >>> +++ b/fs/f2fs/gc.c
> >>> @@ -2197,29 +2197,37 @@ int f2fs_gc_range(struct f2fs_sb_info *sbi,
> >>>       return 0;
> >>>   }
> >>>
> >>> +void f2fs_reset_gc_victim_resource(struct f2fs_sb_info *sbi,
> >>> +                     unsigned int start, unsigned int end)
> >>> +{
> >>> +     int i;
> >>> +
> >>> +     mutex_lock(&DIRTY_I(sbi)->seglist_lock);
> >>> +     for (i = 0; i < MAX_GC_POLICY; i++)
> >>> +             if (SIT_I(sbi)->last_victim[i] >= start &&
> >>> +                     SIT_I(sbi)->last_victim[i] <= end)
> >>> +                     SIT_I(sbi)->last_victim[i] = 0;
> >>> +
> >>> +     for (i = BG_GC; i <= FG_GC; i++)
> >>> +             if (sbi->next_victim_seg[i] >= start &&
> >>> +                     sbi->next_victim_seg[i] <= end)
> >>> +                     sbi->next_victim_seg[i] = NULL_SEGNO;
> >>> +     mutex_unlock(&DIRTY_I(sbi)->seglist_lock);
> >>> +}
> >>> +
> >>>   static int free_segment_range(struct f2fs_sb_info *sbi,
> >>>                               unsigned int secs, bool dry_run)
> >>>   {
> >>>       unsigned int next_inuse, start, end;
> >>>       struct cp_control cpc = { CP_RESIZE, 0, 0, 0 };
> >>> -     int gc_mode, gc_type;
> >>>       int err = 0;
> >>>       int type;
> >>>
> >>> -     /* Force block allocation for GC */
> >>>       MAIN_SECS(sbi) -= secs;
> >>>       start = MAIN_SECS(sbi) * SEGS_PER_SEC(sbi);
> >>>       end = MAIN_SEGS(sbi) - 1;
> >>>
> >>> -     mutex_lock(&DIRTY_I(sbi)->seglist_lock);
> >>> -     for (gc_mode = 0; gc_mode < MAX_GC_POLICY; gc_mode++)
> >>> -             if (SIT_I(sbi)->last_victim[gc_mode] >= start)
> >>> -                     SIT_I(sbi)->last_victim[gc_mode] = 0;
> >>> -
> >>> -     for (gc_type = BG_GC; gc_type <= FG_GC; gc_type++)
> >>> -             if (sbi->next_victim_seg[gc_type] >= start)
> >>> -                     sbi->next_victim_seg[gc_type] = NULL_SEGNO;
> >>> -     mutex_unlock(&DIRTY_I(sbi)->seglist_lock);
> >>> +     f2fs_reset_gc_victim_resource(sbi, start, end);
> >>>
> >>>       /* Move out cursegs from the target range */
> >>>       for (type = CURSEG_HOT_DATA; type < NR_CURSEG_PERSIST_TYPE; type++) {
> >>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> >>> index cac03b8e91a1..8c3b57987f6c 100644
> >>> --- a/fs/f2fs/namei.c
> >>> +++ b/fs/f2fs/namei.c
> >>> @@ -425,6 +425,9 @@ static int f2fs_link(struct dentry *old_dentry, struct inode *dir,
> >>>       if (!f2fs_is_checkpoint_ready(sbi))
> >>>               return -ENOSPC;
> >>>
> >>> +     if (IS_DEVICE_ALIASING(inode))
> >>> +             return -EPERM;
> >>> +
> >>>       err = fscrypt_prepare_link(old_dentry, dir, dentry);
> >>>       if (err)
> >>>               return err;
> >>> @@ -568,6 +571,9 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
> >>>
> >>>       trace_f2fs_unlink_enter(dir, dentry);
> >>>
> >>> +     if (IS_DEVICE_ALIASING(inode))
> >>> +             return -EPERM;
> >>> +
> >>>       if (unlikely(f2fs_cp_error(sbi))) {
> >>>               err = -EIO;
> >>>               goto out;
> >>> @@ -946,6 +952,9 @@ static int f2fs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
> >>>       bool old_is_dir = S_ISDIR(old_inode->i_mode);
> >>>       int err;
> >>>
> >>> +     if (IS_DEVICE_ALIASING(old_inode))
> >>> +             return -EPERM;
> >>> +
> >>>       if (unlikely(f2fs_cp_error(sbi)))
> >>>               return -EIO;
> >>>       if (!f2fs_is_checkpoint_ready(sbi))
> >>> @@ -1016,6 +1025,8 @@ static int f2fs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
> >>>       }
> >>>
> >>>       if (new_inode) {
> >>> +             if (IS_DEVICE_ALIASING(new_inode))
> >>> +                     return -EPERM;
> >>>
> >>>               err = -ENOTEMPTY;
> >>>               if (old_is_dir && !f2fs_empty_dir(new_inode))
> >>> @@ -1143,6 +1154,9 @@ static int f2fs_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>>       int old_nlink = 0, new_nlink = 0;
> >>>       int err;
> >>>
> >>> +     if (IS_DEVICE_ALIASING(old_inode) || IS_DEVICE_ALIASING(new_inode))
> >>> +             return -EPERM;
> >>> +
> >>>       if (unlikely(f2fs_cp_error(sbi)))
> >>>               return -EIO;
> >>>       if (!f2fs_is_checkpoint_ready(sbi))
> >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >>> index d71ddb3ee918..1a986f1884f2 100644
> >>> --- a/fs/f2fs/segment.c
> >>> +++ b/fs/f2fs/segment.c
> >>> @@ -2502,35 +2502,42 @@ static int update_sit_entry_for_alloc(struct f2fs_sb_info *sbi, struct seg_entry
> >>>                               unsigned int segno, block_t blkaddr, unsigned int offset, int del)
> >>>   {
> >>>       bool exist;
> >>> +     int del_count = del;
> >>> +     int i;
> >>>
> >>> -     exist = f2fs_test_and_set_bit(offset, se->cur_valid_map);
> >>> -     if (unlikely(exist)) {
> >>> -             f2fs_err(sbi, "Bitmap was wrongly set, blk:%u", blkaddr);
> >>> -             f2fs_bug_on(sbi, 1);
> >>> -             se->valid_blocks--;
> >>> -             del = 0;
> >>> -     }
> >>> +     f2fs_bug_on(sbi, GET_SEGNO(sbi, blkaddr) != GET_SEGNO(sbi, blkaddr + del_count - 1));
> >>>
> >>> -     if (f2fs_block_unit_discard(sbi) &&
> >>> -                     !f2fs_test_and_set_bit(offset, se->discard_map))
> >>> -             sbi->discard_blks--;
> >>> +     for (i = 0; i < del_count; i++) {
> >>> +             exist = f2fs_test_and_set_bit(offset + i, se->cur_valid_map);
> >>> +             if (unlikely(exist)) {
> >>> +                     f2fs_err(sbi, "Bitmap was wrongly set, blk:%u", blkaddr + i);
> >>> +                     f2fs_bug_on(sbi, 1);
> >>> +                     se->valid_blocks--;
> >>> +                     del -= 1;
> >>> +                     continue;
> >>> +             }
> >>>
> >>> -     /*
> >>> -      * SSR should never reuse block which is checkpointed
> >>> -      * or newly invalidated.
> >>> -      */
> >>> -     if (!is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
> >>> -             if (!f2fs_test_and_set_bit(offset, se->ckpt_valid_map)) {
> >>> -                     se->ckpt_valid_blocks++;
> >>> -                     if (__is_large_section(sbi))
> >>> -                             get_sec_entry(sbi, segno)->ckpt_valid_blocks++;
> >>> +             if (f2fs_block_unit_discard(sbi) &&
> >>> +                             !f2fs_test_and_set_bit(offset + i, se->discard_map))
> >>> +                     sbi->discard_blks--;
> >>> +
> >>> +             /*
> >>> +              * SSR should never reuse block which is checkpointed
> >>> +              * or newly invalidated.
> >>> +              */
> >>> +             if (!is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
> >>> +                     if (!f2fs_test_and_set_bit(offset + i, se->ckpt_valid_map)) {
> >>> +                             se->ckpt_valid_blocks++;
> >>> +                             if (__is_large_section(sbi))
> >>> +                                     get_sec_entry(sbi, segno)->ckpt_valid_blocks++;
> >>> +                     }
> >>>               }
> >>> -     }
> >>>
> >>> -     if (!f2fs_test_bit(offset, se->ckpt_valid_map)) {
> >>> -             se->ckpt_valid_blocks += del;
> >>> -             if (__is_large_section(sbi))
> >>> -                     get_sec_entry(sbi, segno)->ckpt_valid_blocks += del;
> >>> +             if (!f2fs_test_bit(offset + i, se->ckpt_valid_map)) {
> >>> +                     se->ckpt_valid_blocks += 1;
> >>> +                     if (__is_large_section(sbi))
> >>> +                             get_sec_entry(sbi, segno)->ckpt_valid_blocks += 1;
> >>> +             }
> >>>       }
> >>>
> >>>       if (__is_large_section(sbi))
> >>> @@ -2585,9 +2592,14 @@ void f2fs_invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr,
> >>>       unsigned int segno = GET_SEGNO(sbi, addr);
> >>>       struct sit_info *sit_i = SIT_I(sbi);
> >>>       block_t addr_start = addr, addr_end = addr + len - 1;
> >>> -     unsigned int seg_num = GET_SEGNO(sbi, addr_end) - segno + 1;
> >>> +     unsigned int seg_num;
> >>>       unsigned int i = 1, max_blocks = sbi->blocks_per_seg, cnt;
> >>>
> >>> +     if (len == 0)
> >>> +             return;
> >>> +
> >>> +     seg_num = GET_SEGNO(sbi, addr_end) - segno + 1;
> >>> +
> >>>       f2fs_bug_on(sbi, addr == NULL_ADDR);
> >>>       if (addr == NEW_ADDR || addr == COMPRESS_ADDR)
> >>>               return;
> >>> @@ -2620,6 +2632,52 @@ void f2fs_invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr,
> >>>       up_write(&sit_i->sentry_lock);
> >>>   }
> >>>
> >>> +void f2fs_reserve_device_alias(struct f2fs_sb_info *sbi, block_t addr,
> >>> +                             unsigned int len)
> >>> +{
> >>> +     unsigned int segno = GET_SEGNO(sbi, addr);
> >>> +     struct sit_info *sit_i = SIT_I(sbi);
> >>> +     block_t addr_start = addr, addr_end = addr + len - 1;
> >>> +     unsigned int seg_num;
> >>> +     unsigned int i = 1, max_blocks = sbi->blocks_per_seg, cnt;
> >>> +
> >>> +     if (len == 0)
> >>> +             return;
> >>> +
> >>> +     seg_num = GET_SEGNO(sbi, addr_end) - segno + 1;
> >>> +
> >>> +     down_write(&sit_i->sentry_lock);
> >>> +
> >>> +     if (seg_num == 1)
> >>> +             cnt = len;
> >>> +     else
> >>> +             cnt = max_blocks - GET_BLKOFF_FROM_SEG0(sbi, addr);
> >>> +
> >>> +     do {
> >>> +             update_segment_mtime(sbi, addr_start, 0);
> >>> +             update_sit_entry(sbi, addr_start, cnt);
> >>> +             __set_test_and_inuse(sbi, segno);
> >>> +
> >>> +             /* Remove the segment from PRE (prefree) to prevent checkpoint from freeing it! */
> >>> +             mutex_lock(&DIRTY_I(sbi)->seglist_lock);
> >>> +             if (test_and_clear_bit(segno, DIRTY_I(sbi)->dirty_segmap[PRE]))
> >>> +                     DIRTY_I(sbi)->nr_dirty[PRE]--;
> >>> +             mutex_unlock(&DIRTY_I(sbi)->seglist_lock);
> >>> +
> >>> +             /* add it into dirty seglist */
> >>> +             locate_dirty_segment(sbi, segno);
> >>> +
> >>> +             /* update @addr_start and @cnt and @segno */
> >>> +             addr_start = START_BLOCK(sbi, ++segno);
> >>> +             if (++i == seg_num)
> >>> +                     cnt = GET_BLKOFF_FROM_SEG0(sbi, addr_end) + 1;
> >>> +             else
> >>> +                     cnt = max_blocks;
> >>> +     } while (i <= seg_num);
> >>> +
> >>> +     up_write(&sit_i->sentry_lock);
> >>> +}
> >>> +
> >>>   bool f2fs_is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr)
> >>>   {
> >>>       struct sit_info *sit_i = SIT_I(sbi);
> >>> @@ -2758,8 +2816,13 @@ static int is_next_segment_free(struct f2fs_sb_info *sbi,
> >>>       unsigned int segno = curseg->segno + 1;
> >>>       struct free_segmap_info *free_i = FREE_I(sbi);
> >>>
> >>> -     if (segno < MAIN_SEGS(sbi) && segno % SEGS_PER_SEC(sbi))
> >>> +     if (segno < MAIN_SEGS(sbi) && segno % SEGS_PER_SEC(sbi)) {
> >>> +             int devi = f2fs_target_device_index(sbi, START_BLOCK(sbi, segno));
> >>> +
> >>> +             if (f2fs_dev_is_reserving(sbi, devi))
> >>> +                     return 0;
> >>>               return !test_bit(segno, free_i->free_segmap);
> >>> +     }
> >>>       return 0;
> >>>   }
> >>>
> >>> @@ -2778,6 +2841,7 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
> >>>       unsigned int alloc_policy = sbi->allocate_section_policy;
> >>>       unsigned int alloc_hint = sbi->allocate_section_hint;
> >>>       bool init = true;
> >>> +     bool looped = false;
> >>>       int i;
> >>>       int ret = 0;
> >>>
> >>> @@ -2791,8 +2855,13 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
> >>>       if (!new_sec && ((*newseg + 1) % SEGS_PER_SEC(sbi))) {
> >>>               segno = find_next_zero_bit(free_i->free_segmap,
> >>>                       GET_SEG_FROM_SEC(sbi, hint + 1), *newseg + 1);
> >>> -             if (segno < GET_SEG_FROM_SEC(sbi, hint + 1))
> >>> +             if (segno < GET_SEG_FROM_SEC(sbi, hint + 1)) {
> >>> +                     int devi = f2fs_target_device_index(sbi, START_BLOCK(sbi, segno));
> >>> +
> >>> +                     if (f2fs_dev_is_alloc_blocked(sbi, devi, pinning))
> >>> +                             goto find_other_zone;
> >>>                       goto got_it;
> >>> +             }
> >>>       }
> >>>
> >>>   #ifdef CONFIG_BLK_DEV_ZONED
> >>> @@ -2828,33 +2897,50 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
> >>>   find_other_zone:
> >>>       secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> >>>
> >>> -#ifdef CONFIG_BLK_DEV_ZONED
> >>> -     if (secno >= MAIN_SECS(sbi) && f2fs_sb_has_blkzoned(sbi)) {
> >>> -             /* Write only to sequential zones */
> >>> -             if (sbi->blkzone_alloc_policy == BLKZONE_ALLOC_ONLY_SEQ) {
> >>> -                     hint = GET_SEC_FROM_SEG(sbi, sbi->first_seq_zone_segno);
> >>> -                     secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> >>> -             } else
> >>> -                     secno = find_first_zero_bit(free_i->free_secmap,
> >>> -                                                             MAIN_SECS(sbi));
> >>> -             if (secno >= MAIN_SECS(sbi)) {
> >>> -                     ret = -ENOSPC;
> >>> -                     f2fs_bug_on(sbi, 1);
> >>> -                     goto out_unlock;
> >>> -             }
> >>> -     }
> >>> -#endif
> >>> -
> >>>       if (secno >= MAIN_SECS(sbi)) {
> >>> -             secno = find_first_zero_bit(free_i->free_secmap,
> >>> -                                                     MAIN_SECS(sbi));
> >>> -             if (secno >= MAIN_SECS(sbi)) {
> >>> +             if (looped) {
> >>>                       ret = -ENOSPC;
> >>>                       f2fs_bug_on(sbi, !pinning);
> >>>                       goto out_unlock;
> >>>               }
> >>> +#ifdef CONFIG_BLK_DEV_ZONED
> >>> +             /* Write only to sequential zones */
> >>> +             if (f2fs_sb_has_blkzoned(sbi) &&
> >>> +                     sbi->blkzone_alloc_policy == BLKZONE_ALLOC_ONLY_SEQ)
> >>> +                     hint = GET_SEC_FROM_SEG(sbi, sbi->first_seq_zone_segno);
> >>> +             else
> >>> +#endif
> >>> +                     hint = 0;
> >>> +             looped = true;
> >>> +             goto find_other_zone;
> >>>       }
> >>> +
> >>>       segno = GET_SEG_FROM_SEC(sbi, secno);
> >>> +
> >>> +     if (f2fs_sb_has_device_alias(sbi) && f2fs_is_multi_device(sbi)) {
> >>> +             int devi = f2fs_target_device_index(sbi, START_BLOCK(sbi, segno));
> >>> +
> >>> +             if (f2fs_dev_is_alloc_blocked(sbi, devi, pinning)) {
> >>> +                     unsigned int end_segno;
> >>> +
> >>> +                     while (devi < sbi->s_ndevs &&
> >>> +                             f2fs_dev_is_alloc_blocked(sbi, devi, pinning)) {
> >>> +                             block_t next_blk;
> >>> +
> >>> +                             end_segno = GET_SEGNO(sbi, FDEV(devi).end_blk);
> >>> +                             hint = GET_SEC_FROM_SEG(sbi, end_segno) + 1;
> >>> +
> >>> +                             if (hint >= MAIN_SECS(sbi) || ++devi >= sbi->s_ndevs)
> >>> +                                     break;
> >>> +
> >>> +                             next_blk = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, hint));
> >>> +                             if (next_blk < FDEV(devi).start_blk ||
> >>> +                                     next_blk > FDEV(devi).end_blk)
> >>> +                                     break;
> >>> +                     }
> >>> +                     goto find_other_zone;
> >>> +             }
> >>> +     }
> >>>       zoneno = GET_ZONE_FROM_SEC(sbi, secno);
> >>>
> >>>       /* give up on finding another zone */
> >>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> >>> index b0c06b3580b4..259e4a29b494 100644
> >>> --- a/fs/f2fs/segment.h
> >>> +++ b/fs/f2fs/segment.h
> >>> @@ -954,10 +954,36 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
> >>>                               - (base + 1) + type;
> >>>   }
> >>>
> >>> +static inline bool f2fs_dev_is_reserving(struct f2fs_sb_info *sbi, int devi)
> >>> +{
> >>> +     if (!f2fs_sb_has_device_alias(sbi) || !f2fs_is_multi_device(sbi))
> >>> +             return false;
> >>> +     return FDEV(devi).is_reserving;
> >>> +}
> >>> +
> >>> +static inline bool f2fs_dev_is_alloc_blocked(struct f2fs_sb_info *sbi,
> >>> +                                     int devi, bool pinning)
> >>> +{
> >>> +     if (!f2fs_sb_has_device_alias(sbi) || !f2fs_is_multi_device(sbi))
> >>> +             return false;
> >>> +     return (pinning && FDEV(devi).has_alias) || FDEV(devi).is_reserving;
> >>> +}
> >>> +
> >>>   static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno)
> >>>   {
> >>>       if (is_cursec(sbi, secno) || (sbi->cur_victim_sec == secno))
> >>>               return true;
> >>> +     if (f2fs_sb_has_device_alias(sbi) && f2fs_is_multi_device(sbi)) {
> >>> +             int i;
> >>> +             block_t start_blk = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, secno));
> >>> +
> >>> +             for (i = 0; i < sbi->s_ndevs; i++) {
> >>> +                     if (f2fs_dev_is_reserving(sbi, i) &&
> >>> +                             start_blk >= FDEV(i).start_blk &&
> >>> +                             start_blk <= FDEV(i).end_blk)
> >>> +                             return true;
> >>> +             }
> >>> +     }
> >>>       return false;
> >>>   }
> >>>
> >>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >>> index c448d992ff2a..8359eed903be 100644
> >>> --- a/fs/f2fs/super.c
> >>> +++ b/fs/f2fs/super.c
> >>> @@ -5001,6 +5001,38 @@ static void f2fs_tuning_parameters(struct f2fs_sb_info *sbi)
> >>>       sbi->readdir_ra = true;
> >>>   }
> >>>
> >>> +static void f2fs_restore_device_alias(struct f2fs_sb_info *sbi)
> >>> +{
> >>> +     struct inode *root = d_inode(sbi->sb->s_root);
> >>> +     struct f2fs_dir_entry *de;
> >>> +     struct folio *folio;
> >>> +     int i;
> >>> +
> >>> +     if (!f2fs_sb_has_device_alias(sbi))
> >>> +             return;
> >>> +
> >>> +     for (i = 1; i < sbi->s_ndevs; i++) {
> >>> +             char *name = strrchr(FDEV(i).path, '/');
> >>> +             struct qstr qstr;
> >>> +
> >>> +             name = name ? name + 1 : FDEV(i).path;
> >>> +             qstr.name = name;
> >>> +             qstr.len = strlen(name);
> >>> +
> >>> +             de = f2fs_find_entry(root, &qstr, &folio);
> >>> +             if (de) {
> >>> +                     struct inode *inode = f2fs_iget(sbi->sb, le32_to_cpu(de->ino));
> >>> +
> >>> +                     if (!IS_ERR(inode)) {
> >>> +                             if (IS_DEVICE_ALIASING(inode))
> >>> +                                     FDEV(i).has_alias = true;
> >>> +                             iput(inode);
> >>> +                     }
> >>> +                     f2fs_folio_put(folio, 0);
> >>> +             }
> >>> +     }
> >>> +}
> >>> +
> >>>   static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
> >>>   {
> >>>       struct f2fs_fs_context *ctx = fc->fs_private;
> >>> @@ -5436,6 +5468,8 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
> >>>       f2fs_update_time(sbi, REQ_TIME);
> >>>       clear_sbi_flag(sbi, SBI_CP_DISABLED_QUICK);
> >>>
> >>> +     f2fs_restore_device_alias(sbi);
> >>> +
> >>>       sbi->umount_lock_holder = NULL;
> >>>       return 0;
> >>>
> >>> diff --git a/include/uapi/linux/f2fs.h b/include/uapi/linux/f2fs.h
> >>> index 795e26258355..4409ada2fecb 100644
> >>> --- a/include/uapi/linux/f2fs.h
> >>> +++ b/include/uapi/linux/f2fs.h
> >>> @@ -45,6 +45,9 @@
> >>>   #define F2FS_IOC_START_ATOMIC_REPLACE       _IO(F2FS_IOCTL_MAGIC, 25)
> >>>   #define F2FS_IOC_GET_DEV_ALIAS_FILE _IOR(F2FS_IOCTL_MAGIC, 26, __u32)
> >>>   #define F2FS_IOC_IO_PRIO            _IOW(F2FS_IOCTL_MAGIC, 27, __u32)
> >>> +#define F2FS_IOC_RESERVE_DEV_ALIAS   _IO(F2FS_IOCTL_MAGIC, 28)
> >>> +#define F2FS_IOC_RELEASE_DEV_ALIAS   _IO(F2FS_IOCTL_MAGIC, 29)
> >>> +#define F2FS_IOC_GET_DEV_ALIAS_STATUS        _IOR(F2FS_IOCTL_MAGIC, 30, __u32)
> >>>
> >>>   /*
> >>>    * should be same as XFS_IOC_GOINGDOWN.
> >>> @@ -70,6 +73,10 @@ enum {
> >>>       F2FS_IOPRIO_MAX,
> >>>   };
> >>>
> >>> +/* for F2FS_IOC_GET_DEV_ALIAS_STATUS */
> >>> +#define F2FS_DEV_ALIAS_STATUS_RELEASED       0
> >>> +#define F2FS_DEV_ALIAS_STATUS_RESERVED       1
> >>> +
> >>>   struct f2fs_gc_range {
> >>>       __u32 sync;
> >>>       __u64 start;
> >>
>


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