Add a check on each 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.
Fixes: bc8df7a3dc03 ("ovl: Add an alternative type of whiteout")
Cc: <stable@xxxxxxxxxxxxxxx> # v6.7
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
Hi Alex,
Can you please test this in your environment?
I xwhiteout test in xfstests needs this tweak:
--- a/tests/overlay/084
+++ b/tests/overlay/084
@@ -115,6 +115,7 @@ do_test_xwhiteout()
mkdir -p $basedir/lower $basedir/upper $basedir/work
touch $basedir/lower/regular $basedir/lower/hidden $basedir/upper/hidden
+ setfattr -n $prefix.overlay.feature_xwhiteout -v "y" $basedir/upper
setfattr -n $prefix.overlay.whiteouts -v "y" $basedir/upper
setfattr -n $prefix.overlay.whiteout -v "y" $basedir/upper/hidden
Thanks,
Miklos
fs/overlayfs/namei.c | 10 +++++++---
fs/overlayfs/overlayfs.h | 8 ++++++--
fs/overlayfs/ovl_entry.h | 2 ++
fs/overlayfs/readdir.c | 11 ++++++++---
fs/overlayfs/super.c | 13 ++++++++++++-
fs/overlayfs/util.c | 9 ++++++++-
6 files changed, 43 insertions(+), 10 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..991eb5d5c66c 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -51,6 +51,7 @@ enum ovl_xattr {
OVL_XATTR_PROTATTR,
OVL_XATTR_XWHITEOUT,
OVL_XATTR_XWHITEOUTS,
+ OVL_XATTR_FEATURE_XWHITEOUT,
};
enum ovl_inode_flag {
@@ -492,7 +493,9 @@ 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 +677,8 @@ 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..51729e614f5a 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 feature_xwhiteout;
};
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..4e507ab780f3 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1291,7 +1291,7 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
struct ovl_entry *oe;
struct ovl_layer *layers;
struct cred *cred;
- int err;
+ int err, i;
err = -EIO;
if (WARN_ON(fc->user_ns != current_user_ns()))
@@ -1414,6 +1414,17 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
if (err)
goto out_free_oe;
+ for (i = 0; i < ofs->numlayer; i++) {
+ struct path path = { .mnt = layers[i].mnt };
+
+ if (path.mnt) {
+ path.dentry = path.mnt->mnt_root;
+ err = ovl_path_getxattr(ofs, &path, OVL_XATTR_FEATURE_XWHITEOUT, NULL, 0);
+ if (err >= 0)
+ layers[i].feature_xwhiteout = true;
+ }
+ }
+
/* Show index=off in /proc/mounts for forced r/o mount */
if (!ofs->indexdir) {
ofs->config.index = false;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index c3f020ca13a8..cae8219618e3 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->feature_xwhiteout)
+ return false;
+
/* xattr.whiteouts must be a directory */
if (!d_is_dir(dentry))
return false;
@@ -838,6 +843,7 @@ bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, const struct path *path,
#define OVL_XATTR_PROTATTR_POSTFIX "protattr"
#define OVL_XATTR_XWHITEOUT_POSTFIX "whiteout"
#define OVL_XATTR_XWHITEOUTS_POSTFIX "whiteouts"
+#define OVL_XATTR_FEATURE_XWHITEOUT_POSTFIX "feature_xwhiteout"
#define OVL_XATTR_TAB_ENTRY(x) \
[x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
@@ -855,6 +861,7 @@ const char *const ovl_xattr_table[][2] = {
OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_XWHITEOUT),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_XWHITEOUTS),
+ OVL_XATTR_TAB_ENTRY(OVL_XATTR_FEATURE_XWHITEOUT),
};
int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
--
2.43.0
