An impure directory is a directory with "trusted.overlay.impure" xattr
valued 'y', which indicate that this directory may contain copy-uped
targets from lower layers. In oredr to prevent 'd_ino' change while
copy-up (it create a new inode in upper layer) in getdents(2), impure
xattr will be set in the parent directory, letting overlay filesystem
check and get d_ino from lower origin target to ensure consistent d_ino.
There are three situations of setting impure xattr:
1) Copyup lower target in a directory.
2) Link an origined target (already copy-uped, have origin xattr) into
a directory.
3) Rename an origined target (include merged subdirectories) into a
new directory.
So, if a direcotry which contains several origined targets or redirect
directories, the impure xattr should be set. If not, fix this xattr.
Signed-off-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
---
README.md | 22 +++++++++++++++-
check.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
lib.c | 63 +++++++++++++++++++++++++++++++++++-----------
lib.h | 25 +++++++++++++------
4 files changed, 168 insertions(+), 28 deletions(-)
diff --git a/README.md b/README.md
index 2e6146f..cdbd382 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,26 @@ If an invalid redirect xattr was removed by fsck and there is a corresponding
lower directory with the same name exists, not sure this directory is merged
or not, ask user to make a decision.
+Impure directories
+------------------
+
+An impure directory is a directory with "trusted.overlay.impure" xattr valued
+'y', which indicate that this directory may contain copy-uped targets from lower
+layers. In oredr to prevent 'd_ino' change while copy-up (it create a new
+inode in upper layer) in getdents (see getdents(2)), impure xattr will be set
+in the parent directory, letting overlay filesystem check and get d_ino from
+lower origin target to ensure consistent d_ino.
+
+There are three situations of setting impure xattr:
+1) Copyup lower target in a directory.
+2) Link an origined target (already copy-uped, have origin xattr) into
+ a directory.
+3) Rename an origined target (include merged subdirectories) into a
+ new directory.
+
+So, if a direcotry which contains several origined targets or redirect
+directories, the impure xattr should be set. If not, fix this xattr.
+
Usage
=====
@@ -88,6 +108,6 @@ Todo
mounted with relative path. Should modify kernel together to support.
2. Check and fix invalid redirect xattr through origin xattr.
3. Symbolic link check.
-4. Check origin/impure/nlink xattr.
+4. Check origin/nlink xattr.
5. Check index feature consistency.
6. ...
diff --git a/check.c b/check.c
index 033d4ba..05293c5 100644
--- a/check.c
+++ b/check.c
@@ -111,9 +111,9 @@ static inline bool ovl_is_opaque(const char *pathname)
return is_dir_xattr(pathname, OVL_OPAQUE_XATTR);
}
-static inline int ovl_remove_opaque(const char *pathname)
+static inline bool ovl_is_impure(const char *pathname)
{
- return remove_xattr(pathname, OVL_OPAQUE_XATTR);
+ return is_dir_xattr(pathname, OVL_IMPURE_XATTR);
}
static inline int ovl_set_opaque(const char *pathname)
@@ -121,6 +121,11 @@ static inline int ovl_set_opaque(const char *pathname)
return set_xattr(pathname, OVL_OPAQUE_XATTR, "y", 1);
}
+static inline int ovl_set_impure(const char *pathname)
+{
+ return set_xattr(pathname, OVL_IMPURE_XATTR, "y", 1);
+}
+
static int ovl_get_redirect(const char *pathname, size_t dirlen,
size_t filelen, char **redirect)
{
@@ -166,11 +171,20 @@ static inline int ovl_create_whiteout(const char *pathname)
static inline bool ovl_is_redirect(const char *pathname)
{
- bool exist = false;
- ssize_t ret;
+ bool exist = false;
+ ssize_t ret;
+
+ ret = get_xattr(pathname, OVL_REDIRECT_XATTR, NULL, &exist);
+ return ret ? false : exist;
+}
+
+static inline bool ovl_is_origin(const char *pathname)
+{
+ bool exist = false;
+ ssize_t ret;
- ret = get_xattr(pathname, OVL_REDIRECT_XATTR, NULL, &exist);
- return ret ? false : exist;
+ ret = get_xattr(pathname, OVL_ORIGIN_XATTR, NULL, &exist);
+ return ret ? false : exist;
}
static inline int ovl_ask_action(const char *description, const char *pathname,
@@ -503,6 +517,7 @@ static void ovl_redirect_free(void)
static int ovl_check_redirect(struct scan_ctx *sctx)
{
const char *pathname = sctx->pathname;
+ struct scan_dir_data *parent_ddata = sctx->ddata;
struct ovl_lower_data od = {0};
struct stat cover_st;
bool cover_exist = false;
@@ -545,6 +560,9 @@ static int ovl_check_redirect(struct scan_ctx *sctx)
goto remove_d;
}
+ /* Now, this redirect xattr is valid */
+ if (parent_ddata)
+ parent_ddata->redirects++;
ovl_redirect_entry_add(pathname, sctx->dirtype,
sctx->num, od.path);
@@ -603,9 +621,65 @@ out:
return ret;
}
+/*
+ * Get origin xattr stored in the target. We cannot check validity for
+ * current overlay filesystem, so trust this is valid now.
+ */
+static int ovl_check_origin(struct scan_ctx *sctx)
+{
+ const char *pathname = sctx->pathname;
+ struct scan_dir_data *parent_ddata = sctx->ddata;
+
+ if (!ovl_is_origin(pathname))
+ return 0;
+ if (parent_ddata)
+ parent_ddata->origins++;
+
+ return 0;
+}
+
+/*
+ * If a directory has origined target and redirect subdirectories in it,
+ * it may contain copy-up targets. In order to avoid 'd_ino' change after
+ * lower target copyup or renameed (which will create a new inode),
+ * 'impure xattr' will be setted in the parent directory to indicate
+ * overlayfs show origin 'd_ino' when iterate directory.
+ *
+ * Missing "impure xattr" will cause wrong 'd_ino' in readdir() of impure
+ * directory, so check origined or redirected target in a directory and
+ * fix "impure xattr" if necessary.
+ */
+static int ovl_check_impure(struct scan_ctx *sctx)
+{
+ const char *pathname = sctx->pathname;
+ struct scan_dir_data *cur_ddata = sctx->ddata;
+ int ret = 0;
+
+ /*
+ * Impure xattr should be set if current directory has redirect
+ * directory or origin targets.
+ */
+ if (!cur_ddata->origins && !cur_ddata->redirects)
+ goto out;
+
+ /* Fix impure xattrs */
+ if (!ovl_is_impure(pathname)) {
+ if (ovl_ask_action("Missing impure xattr",
+ pathname, "Fix", 1)) {
+ ret = ovl_set_impure(pathname);
+ if (ret)
+ goto out;
+ }
+ }
+out:
+ return ret;
+}
+
static struct scan_operations ovl_scan_ops = {
.whiteout = ovl_check_whiteout,
.redirect = ovl_check_redirect,
+ .origin = ovl_check_origin,
+ .impure = ovl_check_impure,
};
static void ovl_scan_report(struct scan_ctx *sctx)
diff --git a/lib.c b/lib.c
index 497d357..524246d 100644
--- a/lib.c
+++ b/lib.c
@@ -165,8 +165,17 @@ const char *path_pick(const char *path, int baselen)
return (*p == '/') ? p+1 : p;
}
-static inline int __check_entry(struct scan_ctx *sctx,
- int (*do_check)(struct scan_ctx *))
+static void scan_entry_init(struct scan_ctx *sctx, FTSENT *ftsent)
+{
+ sctx->pathname = ftsent->fts_path;
+ sctx->pathlen = ftsent->fts_pathlen;
+ sctx->filename = ftsent->fts_name;
+ sctx->filelen = ftsent->fts_namelen;
+ sctx->st = ftsent->fts_statp;
+}
+
+static inline int scan_check_entry(int (*do_check)(struct scan_ctx *),
+ struct scan_ctx *sctx)
{
return do_check ? do_check(sctx) : 0;
}
@@ -187,8 +196,6 @@ int scan_dir(struct scan_ctx *sctx, struct scan_operations *sop)
}
while ((ftsent = fts_read(ftsp)) != NULL) {
- int err;
-
print_debug(_("Scan:%-3s %2d %7jd %-40s %s\n"),
(ftsent->fts_info == FTS_D) ? "d" :
(ftsent->fts_info == FTS_DNR) ? "dnr" :
@@ -202,26 +209,54 @@ int scan_dir(struct scan_ctx *sctx, struct scan_operations *sop)
ftsent->fts_path, ftsent->fts_name);
/* Fillup base context */
- sctx->pathname = ftsent->fts_path;
- sctx->pathlen = ftsent->fts_pathlen;
- sctx->filename = ftsent->fts_name;
- sctx->filelen = ftsent->fts_namelen;
- sctx->st = ftsent->fts_statp;
+ scan_entry_init(sctx, ftsent);
switch (ftsent->fts_info) {
case FTS_F:
sctx->files++;
+
+ /* Check origin */
+ ret = scan_check_entry(sop->origin, sctx);
+ if (ret)
+ goto out;
break;
case FTS_DEFAULT:
/* Check whiteouts */
- err = __check_entry(sctx, sop->whiteout);
- ret = (err) ? err : ret;
+ ret = scan_check_entry(sop->whiteout, sctx);
+ if (ret)
+ goto out;
+
+ /* Check origin */
+ ret = scan_check_entry(sop->origin, sctx);
+ if (ret)
+ goto out;
break;
case FTS_D:
- /* Check redirect xattr */
sctx->directories++;
- err = __check_entry(sctx, sop->redirect);
- ret = (err) ? err : ret;
+
+ /* Check redirect xattr */
+ ret = scan_check_entry(sop->redirect, sctx);
+ if (ret)
+ goto out;
+
+ /* Check origin */
+ ret = scan_check_entry(sop->origin, sctx);
+ if (ret)
+ goto out;
+
+ /* Save current dir data and create new one */
+ ftsent->fts_pointer = sctx->ddata;
+ sctx->ddata = smalloc(sizeof(struct scan_dir_data));
+ break;
+ case FTS_DP:
+ /* Check impure xattr */
+ ret = scan_check_entry(sop->impure, sctx);
+ if (ret)
+ goto out;
+
+ /* Restore parent's dir data */
+ free(sctx->ddata);
+ sctx->ddata = ftsent->fts_pointer;
break;
case FTS_NS:
case FTS_DNR:
diff --git a/lib.h b/lib.h
index 5d94836..5fec773 100644
--- a/lib.h
+++ b/lib.h
@@ -52,33 +52,44 @@
/* Xattr */
#define OVL_OPAQUE_XATTR "trusted.overlay.opaque"
#define OVL_REDIRECT_XATTR "trusted.overlay.redirect"
+#define OVL_ORIGIN_XATTR "trusted.overlay.origin"
+#define OVL_IMPURE_XATTR "trusted.overlay.impure"
-/* Directories scan data struct */
+/* Directories scan data structs */
+struct scan_dir_data {
+ int origins; /* origin number in this directory (no iterate) */
+ int redirects; /* redirect number in this directory (no iterate) */
+};
+
struct scan_ctx {
const char *dirname; /* upper/lower root dir */
size_t dirlen; /* strlen(dirlen) */
int dirtype; /* OVL_UPPER or OVL_LOWER */
int num; /* lower dir depth, lower type use only */
+ int files; /* total files */
+ int directories; /* total directories */
+ int t_whiteouts; /* total whiteouts */
+ int i_whiteouts; /* invalid whiteouts */
+ int t_redirects; /* total redirect dirs */
+ int i_redirects; /* invalid redirect dirs */
+
const char *pathname; /* file path from the root */
size_t pathlen; /* strlen(pathname) */
const char *filename; /* filename */
size_t filelen; /* strlen(filename) */
struct stat *st; /* file stat */
- int files;
- int directories;
- int t_whiteouts; /* total whiteouts */
- int i_whiteouts; /* invalid whiteouts */
- int t_redirects; /* total redirect dirs */
- int i_redirects; /* invalid redirect dirs */
+ struct scan_dir_data *ddata; /* parent dir data of current target */
};
/* Directories scan callback operations struct */
struct scan_operations {
int (*whiteout)(struct scan_ctx *);
int (*redirect)(struct scan_ctx *);
+ int (*origin)(struct scan_ctx *);
+ int (*impure)(struct scan_ctx *);
};
static inline void set_st_inconsistency(int *st)
--
2.9.5
--
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