6.12-stable review patch. If anyone has any objections, please let me know.
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From: Hongbo Li lihongbo22@huawei.com
[ Upstream commit 510de8363f2c3d8e67fa9dfb2366e821382036e0 ]
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 larger than 128GiB.
Let's introduce our own helpers to encode file handles.
It's easy to reproduce: 1. prepare an erofs image with nid bigger 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 U32_MAX. # you will get ESTALE error.
In the case of overlayfs, the underlying filesystem's file handle is encoded in ovl_fb.fid, which is similar to NFS's case. If the NID of file is larger than U32_MAX, the overlay will get -ESTALE error when calls exportfs_decode_fh.
Fixes: 3e917cc305c6 ("erofs: make filesystem exportable") Signed-off-by: Hongbo Li lihongbo22@huawei.com Reviewed-by: Gao Xiang hsiangkao@linux.alibaba.com Link: https://lore.kernel.org/r/20250507094015.14007-1-lihongbo22@huawei.com Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/erofs/super.c | 44 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 8 deletions(-)
diff --git a/fs/erofs/super.c b/fs/erofs/super.c index 3421448fef0e3..1143e1913f25b 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -537,24 +537,52 @@ 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); + erofs_nid_t nid = EROFS_I(inode)->nid; + int len = parent ? 6 : 3; + + if (*max_len < len) { + *max_len = len; + return FILEID_INVALID; + } + + fh[0] = (u32)(nid >> 32); + fh[1] = (u32)(nid & 0xffffffff); + fh[2] = inode->i_generation; + + if (parent) { + nid = EROFS_I(parent)->nid; + + fh[3] = (u32)(nid >> 32); + fh[4] = (u32)(nid & 0xffffffff); + 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); + if ((fh_type != FILEID_INO64_GEN && + fh_type != FILEID_INO64_GEN_PARENT) || fh_len < 3) + return NULL; + + 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); + if (fh_type != FILEID_INO64_GEN_PARENT || fh_len < 6) + return NULL; + + return d_obtain_alias(erofs_iget(sb, + ((u64)fid->raw[3] << 32) | fid->raw[4])); }
static struct dentry *erofs_get_parent(struct dentry *child) @@ -570,7 +598,7 @@ static struct dentry *erofs_get_parent(struct dentry *child) }
static const struct export_operations erofs_export_ops = { - .encode_fh = generic_encode_ino32_fh, + .encode_fh = erofs_encode_fh, .fh_to_dentry = erofs_fh_to_dentry, .fh_to_parent = erofs_fh_to_parent, .get_parent = erofs_get_parent,