Overlayfs can now work on filesystems that support casefolding, provided
the specific subtree overlayfs is using as layers don't have casefolding
enabled.
d_casefold_disabled_get() and put() are used, which check that
casefolding is enabled nowhere on a given subtree, and get and release a
reference that prevents the filesystem from enabling casefolding on that
tree while overlayfs is in use.
We also now check the new SB_CASEFOLD superblock flag; if it's set we
allow for dcache hash and compare ops to be set, relying instead on the
new dcache methods.
Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: Amir Goldstein <amir73il@xxxxxxxxx>
Cc: linux-unionfs@xxxxxxxxxxxxxxx
Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
---
fs/overlayfs/params.c | 20 +++++++++++++++++---
fs/overlayfs/util.c | 19 +++++++++++++++----
2 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index 6759f7d040c8..ae7424e075a7 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -287,7 +287,8 @@ static int ovl_mount_dir_check(struct fs_context *fc, const struct path *path,
* with overlayfs. Check explicitly to prevent post-mount
* failures.
*/
- if (sb_has_encoding(path->mnt->mnt_sb))
+ if ((path->mnt->mnt_sb->s_flags & SB_CASEFOLD) &&
+ !(path->dentry->d_inode->i_flags & S_NO_CASEFOLD))
return invalfc(fc, "case-insensitive capable filesystem on %s not supported", name);
if (ovl_dentry_weird(path->dentry))
@@ -411,20 +412,32 @@ static int ovl_do_parse_layer(struct fs_context *fc, const char *layer_name,
if (!name)
return -ENOMEM;
+ if (layer != Opt_workdir &&
+ layer != Opt_upperdir) {
+ err = d_casefold_disabled_get(layer_path->dentry);
+ if (err)
+ return err;
+ }
+
upper = is_upper_layer(layer);
err = ovl_mount_dir_check(fc, layer_path, layer, name, upper);
if (err)
- return err;
+ goto err_put;
if (!upper) {
err = ovl_ctx_realloc_lower(fc);
if (err)
- return err;
+ goto err_put;
}
/* Store the user provided path string in ctx to show in mountinfo */
ovl_add_layer(fc, layer, layer_path, &name);
return err;
+err_put:
+ if (layer != Opt_workdir &&
+ layer != Opt_upperdir)
+ d_casefold_disabled_put(layer_path->dentry);
+ return err;
}
static int ovl_parse_layer(struct fs_context *fc, struct fs_parameter *param,
@@ -475,6 +488,7 @@ static void ovl_reset_lowerdirs(struct ovl_fs_context *ctx)
ctx->lowerdir_all = NULL;
for (size_t nr = 0; nr < ctx->nr; nr++, l++) {
+ d_casefold_disabled_put(l->path.dentry);
path_put(&l->path);
kfree(l->name);
l->name = NULL;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 0819c739cc2f..c515f260032c 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -205,10 +205,21 @@ bool ovl_dentry_weird(struct dentry *dentry)
if (!d_can_lookup(dentry) && !d_is_file(dentry) && !d_is_symlink(dentry))
return true;
- return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
- DCACHE_MANAGE_TRANSIT |
- DCACHE_OP_HASH |
- DCACHE_OP_COMPARE);
+ if (dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
+ DCACHE_MANAGE_TRANSIT))
+ return true;
+
+ /*
+ * The filesystem might support casefolding, but we've already checked
+ * that casefolding isn't present on this tree: we only need to check
+ * for non-casefolding hash/compare ops
+ */
+ if (!(dentry->d_sb->s_flags & SB_CASEFOLD) &&
+ (dentry->d_flags & (DCACHE_OP_HASH |
+ DCACHE_OP_COMPARE)))
+ return true;
+
+ return false;
}
enum ovl_path_type ovl_path_type(struct dentry *dentry)
--
2.49.0
