[PATCH 1/2] f2fs: persist device alias inode across remount
From: Wenjie Qi
Date: Wed Aug 26 2026 - 09:44:55 EST
A released device alias loses its extent. Reserve then identifies the
target device by matching the alias filename against the device basename,
which fails when mkfs used a custom alias name.
Store each alias inode number at its device index in the superblock
reserved area. Record the mapping before releasing blocks and use it to
identify the device during reserve. Reject conflicting mappings and keep
the basename lookup for images without a recorded mapping.
Leave released alias inodes without an extent so existing fsck does not
account the freed device range as live blocks.
Fixes: eae3faf210bd ("f2fs: support dynamic reserve/release for device aliasing")
Signed-off-by: Wenjie Qi <qiwenjie@xxxxxxxxxx>
---
fs/f2fs/file.c | 96 +++++++++++++++++++++++++++++++++++------
include/linux/f2fs_fs.h | 3 +-
2 files changed, 84 insertions(+), 15 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index d440231b8cb9..7f1dc00031ba 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3725,25 +3725,44 @@ static int f2fs_ioc_get_dev_alias_file(struct file *filp, unsigned long arg)
(u32 __user *)arg);
}
-static bool f2fs_get_dev_alias_extent(struct f2fs_sb_info *sbi,
- struct dentry *dentry,
- struct extent_info *ei)
+static int f2fs_get_dev_alias_index(struct f2fs_sb_info *sbi,
+ struct inode *inode,
+ struct dentry *dentry)
{
+ int devi = -ENOENT;
int i;
+ f2fs_down_read(&sbi->sb_lock);
+ for (i = 0; i < MAX_DEVICES; i++) {
+ if (le32_to_cpu(sbi->raw_super->dev_alias_ino[i]) !=
+ inode->i_ino)
+ continue;
+ if (!i || i >= sbi->s_ndevs) {
+ devi = -EFSCORRUPTED;
+ goto out;
+ }
+ if (devi >= 0) {
+ devi = -EFSCORRUPTED;
+ goto out;
+ }
+ devi = i;
+ }
+ if (devi >= 0)
+ goto out;
+
for (i = 1; i < sbi->s_ndevs; i++) {
char *name = strrchr(FDEV(i).path, '/');
name = name ? name + 1 : FDEV(i).path;
if (strcmp(name, dentry->d_name.name))
continue;
-
- ei->blk = FDEV(i).start_blk;
- ei->len = FDEV(i).total_segments << sbi->log_blocks_per_seg;
- ei->fofs = 0;
- return true;
+ devi = sbi->raw_super->dev_alias_ino[i] ?
+ -EFSCORRUPTED : i;
+ break;
}
- return false;
+out:
+ f2fs_up_read(&sbi->sb_lock);
+ return devi;
}
static int f2fs_ioc_reserve_dev_alias(struct file *filp)
@@ -3756,7 +3775,7 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
struct f2fs_lock_context lc, glc;
blkcnt_t count;
unsigned int start, end;
- int type, err;
+ int devi, type, err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -3780,7 +3799,8 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
goto out_inode_unlock;
}
- if (!f2fs_get_dev_alias_extent(sbi, filp->f_path.dentry, &ei)) {
+ devi = f2fs_get_dev_alias_index(sbi, inode, filp->f_path.dentry);
+ if (devi < 0) {
f2fs_warn(sbi, "device alias file (%s, ino=%llu) has no matching device",
filp->f_path.dentry->d_name.name,
(unsigned long long)inode->i_ino);
@@ -3790,6 +3810,10 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
goto out_inode_unlock;
}
+ ei.blk = FDEV(devi).start_blk;
+ ei.len = FDEV(devi).total_segments << sbi->log_blocks_per_seg;
+ ei.fofs = 0;
+
spin_lock(&sbi->stat_lock);
if (sbi->total_valid_block_count + ei.len >
get_available_block_count(sbi, inode, true)) {
@@ -3801,7 +3825,7 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
spin_unlock(&sbi->stat_lock);
spin_lock(&FREE_I(sbi)->segmap_lock);
- FDEV(f2fs_target_device_index(sbi, ei.blk)).is_reserving = true;
+ FDEV(devi).is_reserving = true;
spin_unlock(&FREE_I(sbi)->segmap_lock);
start = GET_SEGNO(sbi, ei.blk);
@@ -3853,7 +3877,7 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
f2fs_update_inode_page(inode);
spin_lock(&FREE_I(sbi)->segmap_lock);
- FDEV(f2fs_target_device_index(sbi, ei.blk)).is_reserving = false;
+ FDEV(devi).is_reserving = false;
spin_unlock(&FREE_I(sbi)->segmap_lock);
f2fs_unlock_op(sbi, &lc);
@@ -3870,7 +3894,7 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
spin_unlock(&sbi->stat_lock);
spin_lock(&FREE_I(sbi)->segmap_lock);
- FDEV(f2fs_target_device_index(sbi, ei.blk)).is_reserving = false;
+ FDEV(devi).is_reserving = false;
spin_unlock(&FREE_I(sbi)->segmap_lock);
f2fs_up_write_trace(&sbi->gc_lock, &glc);
@@ -3880,6 +3904,44 @@ static int f2fs_ioc_reserve_dev_alias(struct file *filp)
return err;
}
+static int f2fs_record_dev_alias_inode(struct f2fs_sb_info *sbi,
+ struct inode *inode, int devi)
+{
+ __le32 old_ino;
+ int err = 0;
+ int i;
+
+ f2fs_down_write(&sbi->sb_lock);
+ old_ino = sbi->raw_super->dev_alias_ino[devi];
+ if (old_ino && le32_to_cpu(old_ino) != inode->i_ino)
+ goto conflict;
+
+ for (i = 0; i < MAX_DEVICES; i++) {
+ if (i != devi &&
+ le32_to_cpu(sbi->raw_super->dev_alias_ino[i]) ==
+ inode->i_ino)
+ goto conflict;
+ }
+
+ if (!old_ino) {
+ sbi->raw_super->dev_alias_ino[devi] =
+ cpu_to_le32(inode->i_ino);
+ err = f2fs_commit_super(sbi, false);
+ if (err)
+ sbi->raw_super->dev_alias_ino[devi] = old_ino;
+ }
+ goto out;
+
+conflict:
+ f2fs_warn(sbi, "conflicting device alias inode mapping for device %d",
+ devi);
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ err = -EFSCORRUPTED;
+out:
+ f2fs_up_write(&sbi->sb_lock);
+ return err;
+}
+
static int f2fs_ioc_release_dev_alias(struct file *filp)
{
struct inode *inode = file_inode(filp);
@@ -3888,6 +3950,7 @@ static int f2fs_ioc_release_dev_alias(struct file *filp)
struct extent_info ei = {0, };
struct cp_control cpc = { CP_SYNC, 0, 0, 0 };
struct f2fs_lock_context lc, glc;
+ int devi;
int err;
if (!capable(CAP_SYS_ADMIN))
@@ -3920,6 +3983,11 @@ static int f2fs_ioc_release_dev_alias(struct file *filp)
ei = et->largest;
read_unlock(&et->lock);
+ devi = f2fs_target_device_index(sbi, ei.blk);
+ err = f2fs_record_dev_alias_inode(sbi, inode, devi);
+ if (err)
+ goto out_inode_unlock;
+
f2fs_down_write_trace(&sbi->gc_lock, &glc);
f2fs_lock_op(sbi, &lc);
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index bb2b6cd5d507..2130bacdbe93 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -158,7 +158,8 @@ struct f2fs_super_block {
__le16 s_encoding_flags; /* Filename charset encoding flags */
__u8 s_stop_reason[MAX_STOP_REASON]; /* stop checkpoint reason */
__u8 s_errors[MAX_F2FS_ERRORS]; /* reason of image corrupts */
- __u8 reserved[258]; /* valid reserved region */
+ __le32 dev_alias_ino[MAX_DEVICES]; /* device alias inode numbers */
+ __u8 reserved[226]; /* valid reserved region */
__le32 crc; /* checksum of superblock */
} __packed;
--
2.43.0