Hi Hongbo,
On 2025/4/29 21:42, Hongbo Li wrote:
In erofs, the inode number has the location information of
files. The default encode_fh uses the ino32, this will lack
of some information when the file is too big. So we need
the internal helpers to encode filehandle.
EROFS uses NID to indicate the on-disk inode offset, which can
exceed 32 bits. However, the default encode_fh uses the ino32,
thus it doesn't work if the image is large than 128GiB.
Let's introduce our own helpers to encode file handles.
It is easy to reproduce test:
It's easy to reproduce:
1. prepare an erofs image with nid bigger than UINT_MAX
1. Prepare an EROFS image with NIDs larger than U32_MAX
2. mount -t erofs foo.img /mnt/erofs
3. set exportfs with configuration: /mnt/erofs *(rw,sync,
no_root_squash)
4. mount -t nfs $IP:/mnt/erofs /mnt/nfs
5. md5sum /mnt/nfs/foo # foo is the file which nid bigger
than UINT_MAX.
For overlayfs case, the under filesystem's file handle is
encoded in ovl_fb.fid, it is same as NFS's case.
Fixes: 3e917cc305c6 ("erofs: make filesystem exportable")
Signed-off-by: Hongbo Li <lihongb...@huawei.com>
---
v2: https://lore.kernel.org/all/20250429074109.689075-1-lihongb...@huawei.com/
- Assign parent nid with correct value.
v1: https://lore.kernel.org/all/20250429011139.686847-1-lihongb...@huawei.com/
- Encode generation into file handle and minor clean code.
- Update the commiti's title.
---
fs/erofs/super.c | 54 +++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 46 insertions(+), 8 deletions(-)
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index cadec6b1b554..28b3701165cc 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -511,24 +511,62 @@ static int erofs_fc_parse_param(struct fs_context *fc,
return 0;
}
-static struct inode *erofs_nfs_get_inode(struct super_block *sb,
- u64 ino, u32 generation)
+static int erofs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
+ struct inode *parent)
{
- return erofs_iget(sb, ino);
+ int len = parent ? 6 : 3;
+ erofs_nid_t nid;
Just `erofs_nid_t nid = EROFS_I(inode)->nid;`?
I think the compiler will optimize out `if (*max_len < len)`.
+ u32 generation;
It seems it's unnecessary to introduce `generation` variable here?
+
+ if (*max_len < len) {
+ *max_len = len;
+ return FILEID_INVALID;
+ }
+
+ nid = EROFS_I(inode)->nid;
+ generation = inode->i_generation;
So drop these two lines.
+ fh[0] = (u32)(nid >> 32);
+ fh[1] = (u32)(nid & 0xffffffff);
+ fh[2] = generation;
+
+ if (parent) {
+ nid = EROFS_I(parent)->nid;
+ generation = parent->i_generation;
+
+ fh[3] = (u32)(nid >> 32);
+ fh[4] = (u32)(nid & 0xffffffff);
+ fh[5] = generation;
fh[5] = parent->i_generation;
+ }
+
+ *max_len = len;
+ return parent ? FILEID_INO64_GEN_PARENT : FILEID_INO64_GEN;
}
static struct dentry *erofs_fh_to_dentry(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
- return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
- erofs_nfs_get_inode);
+ erofs_nid_t nid;
+
+ if ((fh_type != FILEID_INO64_GEN &&
+ fh_type != FILEID_INO64_GEN_PARENT) || fh_len < 3)
+ return NULL;
+
+ nid = (u64) fid->raw[0] << 32;
+ nid |= (u64) fid->raw[1];
Unnecessary nid variable.
+ return d_obtain_alias(erofs_iget(sb, nid));
return d_obtain_alias(erofs_iget(sb,
((u64)fid->raw[0] << 32) | fid->raw[1]));
}
static struct dentry *erofs_fh_to_parent(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
- return generic_fh_to_parent(sb, fid, fh_len, fh_type,
- erofs_nfs_get_inode);
+ erofs_nid_t nid;
+
+ if (fh_type != FILEID_INO64_GEN_PARENT || fh_len < 6)
+ return NULL;
+
+ nid = (u64) fid->raw[3] << 32;
+ nid |= (u64) fid->raw[4];
Same here.
Thanks,
Gao Xiang
