Add a check on each lower layer for the xwhiteout feature. This prevents
unnecessary checking the overlay.whiteouts xattr when reading a directory
if this feature is not enabled, i.e. most of the time.
Share the same xattr for the per-directory and the per-layer flag, which
has the effect that if this is enabled for a layer, then the optimization
to bypass checking of individual entries does not work on the root of the
layer. This was deemed better, than having a separate xattr for the layer
and the directory.
Fixes: bc8df7a3dc03 ("ovl: Add an alternative type of whiteout")
Cc: <stable@xxxxxxxxxxxxxxx> # v6.7
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
v2:
- use overlay.whiteouts instead of overlay.feature_xwhiteout
- move initialization to ovl_get_layers()
- xwhiteouts can only be enabled on lower layer
fs/overlayfs/namei.c | 10 +++++++---
fs/overlayfs/overlayfs.h | 7 +++++--
fs/overlayfs/ovl_entry.h | 2 ++
fs/overlayfs/readdir.c | 11 ++++++++---
fs/overlayfs/super.c | 13 +++++++++++++
fs/overlayfs/util.c | 7 ++++++-
6 files changed, 41 insertions(+), 9 deletions(-)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 03bc8d5dfa31..583cf56df66e 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -863,7 +863,8 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
* Returns next layer in stack starting from top.
* Returns -1 if this is the last layer.
*/
-int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path,
+ const struct ovl_layer **layer)
{
struct ovl_entry *oe = OVL_E(dentry);
struct ovl_path *lowerstack = ovl_lowerstack(oe);
@@ -871,13 +872,16 @@ int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
BUG_ON(idx < 0);
if (idx == 0) {
ovl_path_upper(dentry, path);
- if (path->dentry)
+ if (path->dentry) {
+ *layer = &OVL_FS(dentry->d_sb)->layers[0];
return ovl_numlower(oe) ? 1 : -1;
+ }
idx++;
}
BUG_ON(idx > ovl_numlower(oe));
path->dentry = lowerstack[idx - 1].dentry;
- path->mnt = lowerstack[idx - 1].layer->mnt;
+ *layer = lowerstack[idx - 1].layer;
+ path->mnt = (*layer)->mnt;
return (idx < ovl_numlower(oe)) ? idx + 1 : -1;
}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 05c3dd597fa8..6359cf5c66ff 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -492,7 +492,9 @@ bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, const struct path *path,
enum ovl_xattr ox);
bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, const struct path *path);
bool ovl_path_check_xwhiteout_xattr(struct ovl_fs *ofs, const struct path *path);
-bool ovl_path_check_xwhiteouts_xattr(struct ovl_fs *ofs, const struct path *path);
+bool ovl_path_check_xwhiteouts_xattr(struct ovl_fs *ofs,
+ const struct ovl_layer *layer,
+ const struct path *path);
bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs,
const struct path *upperpath);
@@ -674,7 +676,8 @@ int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin,
struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
struct dentry *origin, bool verify);
-int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path,
+ const struct ovl_layer **layer);
int ovl_verify_lowerdata(struct dentry *dentry);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index d82d2a043da2..33fcd3d3af30 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -40,6 +40,8 @@ struct ovl_layer {
int idx;
/* One fsid per unique underlying sb (upper fsid == 0) */
int fsid;
+ /* xwhiteouts are enabled on this layer*/
+ bool xwhiteouts;
};
struct ovl_path {
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index a490fc47c3e7..c2597075e3f8 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -305,8 +305,6 @@ static inline int ovl_dir_read(const struct path *realpath,
if (IS_ERR(realfile))
return PTR_ERR(realfile);
- rdd->in_xwhiteouts_dir = rdd->dentry &&
- ovl_path_check_xwhiteouts_xattr(OVL_FS(rdd->dentry->d_sb), realpath);
rdd->first_maybe_whiteout = NULL;
rdd->ctx.pos = 0;
do {
@@ -359,10 +357,14 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list,
.is_lowest = false,
};
int idx, next;
+ struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
+ const struct ovl_layer *layer;
for (idx = 0; idx != -1; idx = next) {
- next = ovl_path_next(idx, dentry, &realpath);
+ next = ovl_path_next(idx, dentry, &realpath, &layer);
rdd.is_upper = ovl_dentry_upper(dentry) == realpath.dentry;
+ if (ovl_path_check_xwhiteouts_xattr(ofs, layer, &realpath))
+ rdd.in_xwhiteouts_dir = true;
if (next != -1) {
err = ovl_dir_read(&realpath, &rdd);
@@ -568,6 +570,7 @@ static int ovl_dir_read_impure(const struct path *path, struct list_head *list,
int err;
struct path realpath;
struct ovl_cache_entry *p, *n;
+ struct ovl_fs *ofs = OVL_FS(path->dentry->d_sb);
struct ovl_readdir_data rdd = {
.ctx.actor = ovl_fill_plain,
.list = list,
@@ -577,6 +580,8 @@ static int ovl_dir_read_impure(const struct path *path, struct list_head *list,
INIT_LIST_HEAD(list);
*root = RB_ROOT;
ovl_path_upper(path->dentry, &realpath);
+ if (ovl_path_check_xwhiteouts_xattr(ofs, &ofs->layers[0], &realpath))
+ rdd.in_xwhiteouts_dir = true;
err = ovl_dir_read(&realpath, &rdd);
if (err)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index a0967bb25003..04588721eb2a 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1027,6 +1027,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
struct ovl_fs_context_layer *l = &ctx->lower[i];
struct vfsmount *mnt;
struct inode *trap;
+ struct path root;
int fsid;
if (i < nr_merged_lower)
@@ -1069,6 +1070,16 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
*/
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
+ /*
+ * Check if xwhiteout (xattr whiteout) support is enabled on
+ * this layer.
+ */
+ root.mnt = mnt;
+ root.dentry = mnt->mnt_root;
+ err = ovl_path_getxattr(ofs, &root, OVL_XATTR_XWHITEOUTS, NULL, 0);
+ if (err >= 0)
+ layers[ofs->numlayer].xwhiteouts = true;
+
layers[ofs->numlayer].trap = trap;
layers[ofs->numlayer].mnt = mnt;
layers[ofs->numlayer].idx = ofs->numlayer;
@@ -1079,6 +1090,8 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
l->name = NULL;
ofs->numlayer++;
ofs->fs[fsid].is_lower = true;
+
+
}
/*
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index c3f020ca13a8..6c6e6f5893ea 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -739,11 +739,16 @@ bool ovl_path_check_xwhiteout_xattr(struct ovl_fs *ofs, const struct path *path)
return res >= 0;
}
-bool ovl_path_check_xwhiteouts_xattr(struct ovl_fs *ofs, const struct path *path)
+bool ovl_path_check_xwhiteouts_xattr(struct ovl_fs *ofs,
+ const struct ovl_layer *layer,
+ const struct path *path)
{
struct dentry *dentry = path->dentry;
int res;
+ if (!layer->xwhiteouts)
+ return false;
+
/* xattr.whiteouts must be a directory */
if (!d_is_dir(dentry))
return false;
--
2.43.0
