Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
ovl: relax requirement for uuid=off,index=on
uuid=off,index=on required that all upper/lower directories are on the
same filesystem.
Relax the requirement so that only all the lower directories need to be
on the same filesystem.
Reported-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20260114-tonyk-get_disk_uuid-v1-3-e6a319e25d57@igalia.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
+24
-20
+3
-3
Documentation/filesystems/overlayfs.rst
+3
-3
Documentation/filesystems/overlayfs.rst
···
753
753
read-write mount and will result in an error.
754
754
755
755
Note: the mount option uuid=off can be used to replace UUID of the underlying
756
-
filesystem in file handles with null, and effectively disable UUID checks. This
756
+
filesystem in file handles with null, in order to relax the UUID checks. This
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can be useful in case the underlying disk is copied and the UUID of this copy
758
-
is changed. This is only applicable if all lower/upper/work directories are on
758
+
is changed. This is only applicable if all lower directories are on
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the same filesystem, otherwise it will fallback to normal behaviour.
760
760
761
761
···
769
769
UUID of overlayfs is null. fsid is taken from upper most filesystem.
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- "off":
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UUID of overlayfs is null. fsid is taken from upper most filesystem.
772
-
UUID of underlying layers is ignored.
772
+
UUID of underlying layers is ignored and null used instead.
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773
- "on":
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UUID of overlayfs is generated and used to report a unique fsid.
775
775
UUID is stored in xattr "trusted.overlay.uuid", making overlayfs fsid
+13
-8
fs/overlayfs/namei.c
+13
-8
fs/overlayfs/namei.c
···
158
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goto out;
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}
160
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161
+
bool ovl_uuid_match(struct ovl_fs *ofs, const struct super_block *sb,
162
+
const uuid_t *uuid)
163
+
{
164
+
/*
165
+
* Make sure that the stored uuid matches the uuid of the lower
166
+
* layer where file handle will be decoded.
167
+
* In case of uuid=off option just make sure that stored uuid is null.
168
+
*/
169
+
return ovl_origin_uuid(ofs) ? uuid_equal(uuid, &sb->s_uuid) :
170
+
uuid_is_null(uuid);
171
+
}
172
+
161
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struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
162
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struct vfsmount *mnt, bool connected)
163
175
{
···
179
167
if (!capable(CAP_DAC_READ_SEARCH))
180
168
return NULL;
181
169
182
-
/*
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-
* Make sure that the stored uuid matches the uuid of the lower
184
-
* layer where file handle will be decoded.
185
-
* In case of uuid=off option just make sure that stored uuid is null.
186
-
*/
187
-
if (ovl_origin_uuid(ofs) ?
188
-
!uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
189
-
!uuid_is_null(&fh->fb.uuid))
170
+
if (!ovl_uuid_match(ofs, mnt->mnt_sb, &fh->fb.uuid))
190
171
return NULL;
191
172
192
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bytes = (fh->fb.len - offsetof(struct ovl_fb, fid));
+2
fs/overlayfs/overlayfs.h
+2
fs/overlayfs/overlayfs.h
···
710
710
return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET);
711
711
}
712
712
713
+
bool ovl_uuid_match(struct ovl_fs *ofs, const struct super_block *sb,
714
+
const uuid_t *uuid);
713
715
struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
714
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struct vfsmount *mnt, bool connected);
715
717
int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
+6
-9
fs/overlayfs/super.c
+6
-9
fs/overlayfs/super.c
···
940
940
* disable lower file handle decoding on all of them.
941
941
*/
942
942
if (ofs->fs[i].is_lower &&
943
-
uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
943
+
ovl_uuid_match(ofs, ofs->fs[i].sb, uuid)) {
944
944
ofs->fs[i].bad_uuid = true;
945
945
return false;
946
946
}
···
952
952
static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
953
953
{
954
954
struct super_block *sb = path->mnt->mnt_sb;
955
+
const uuid_t *uuid = ovl_origin_uuid(ofs) ? &sb->s_uuid : &uuid_null;
955
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unsigned int i;
956
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dev_t dev;
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int err;
···
964
963
return i;
965
964
}
966
965
967
-
if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) {
966
+
if (!ovl_lower_uuid_ok(ofs, uuid)) {
968
967
bad_uuid = true;
969
968
if (ofs->config.xino == OVL_XINO_AUTO) {
970
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ofs->config.xino = OVL_XINO_OFF;
···
976
975
warn = true;
977
976
}
978
977
if (warn) {
979
-
pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n",
980
-
uuid_is_null(&sb->s_uuid) ? "null" :
981
-
"conflicting",
978
+
pr_warn("%s uuid in non-single lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n",
979
+
uuid_is_null(uuid) ? "null" : "conflicting",
982
980
path->dentry, ovl_xino_mode(&ofs->config));
983
981
}
984
982
}
···
1469
1469
if (!ovl_upper_mnt(ofs))
1470
1470
sb->s_flags |= SB_RDONLY;
1471
1471
1472
-
if (!ovl_origin_uuid(ofs) && ofs->numfs > 1) {
1473
-
pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=null.\n");
1474
-
ofs->config.uuid = OVL_UUID_NULL;
1475
-
} else if (ovl_has_fsid(ofs) && ovl_upper_mnt(ofs)) {
1472
+
if (ovl_has_fsid(ofs) && ovl_upper_mnt(ofs)) {
1476
1473
/* Use per instance persistent uuid/fsid */
1477
1474
ovl_init_uuid_xattr(sb, ofs, &ctx->upper);
1478
1475
}