An impure directory is a directory with "trusted.overlay.impure" xattr
valued 'y', which indicate that this directory may contain copied up
targets from lower layers.
If a target copy-up from lower to upper layer, it's 'd_ino'
(see getdents(2)) will change from lower's 'd_ino' to upper's (a new
inode will be created in upper layer). So the impure xattr should be
set to the parent directory to prompt overlay filesystem to get and
return the origin 'd_ino', thus ensuring the consistentcy of 'd_ino'.
There are three situations of setting impure xattr in overlay
filesystem:
1) Copy-up lower target in a directory.
2) Link an origin target (already copied up, have origin xattr) into a
directory.
3) Rename an origin target (include merge subdirectories) into a new
directory.
So, the impure xattr should be set if a direcotry contains origin
targets or redirect/merge subdirectories. If not, fix the impure xattr.
Signed-off-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
---
README.md | 22 ++++++++++++++++++
check.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
lib.c | 5 ++++
lib.h | 3 +++
4 files changed, 102 insertions(+), 6 deletions(-)
diff --git a/README.md b/README.md
index da6c48c..56aae66 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,28 @@ If not,
3) Record redirect xattrs but not sure which one is invalid, ask user by
default and warn in auto mode.
+Impure directories
+------------------
+
+An impure directory is a directory with "trusted.overlay.impure" xattr valued
+'y', which indicate that this directory may contain copied up targets from lower
+layers.
+If a target copy-up from lower to upper layer, it's 'd_ino' (see getdents(2))
+will change from lower's 'd_ino' to upper's (a new inode will be created in
+upper layer). So the impure xattr should be set to the parent directory to
+prompt overlay filesystem to get and return the origin 'd_ino', thus ensuring
+the consistentcy of 'd_ino'.
+
+There are three situations of setting impure xattr in overlay filesystem:
+1) Copy-up lower target in a directory.
+2) Link an origin target (already copied up, have origin xattr) into a
+ directory.
+3) Rename an origin target (include merge subdirectories) into a new
+ directory.
+
+So, the impure xattr should be set if a direcotry contains origin targets or
+redirect/merge subdirectories. If not, fix the impure xattr.
+
Usage
=====
diff --git a/check.c b/check.c
index f0b3ff4..ca7cd88 100644
--- a/check.c
+++ b/check.c
@@ -132,6 +132,16 @@ static inline int ovl_set_opaque(int dirfd, const char *pathname)
return set_xattr(dirfd, pathname, OVL_OPAQUE_XATTR, "y", 1);
}
+static inline int ovl_is_impure(int dirfd, const char *pathname)
+{
+ return is_dir_xattr(dirfd, pathname, OVL_IMPURE_XATTR);
+}
+
+static inline int ovl_set_impure(int dirfd, const char *pathname)
+{
+ return set_xattr(dirfd, pathname, OVL_IMPURE_XATTR, "y", 1);
+}
+
static int ovl_get_redirect(int dirfd, const char *pathname,
char **redirect)
{
@@ -708,6 +718,54 @@ out:
return ret;
}
+/*
+ * If a directory has origin target and redirect/merge subdirectories in it,
+ * it may contain copied up targets. In order to avoid 'd_ino' change after
+ * lower target copy-up or rename (which will create a new inode),
+ * 'impure xattr' will be set in the parent directory, it is used to prompt
+ * overlay filesystem to get and return the origin 'd_ino' in getdents(2).
+ *
+ * Missing "impure xattr" will lead to return wrong 'd_ino' of impure directory.
+ * So check origin target and redirect/merge subdirs in a specified directory,
+ * and fix "impure xattr" if necessary.
+ */
+static int ovl_check_impure(struct scan_ctx *sctx)
+{
+ struct scan_dir_data *dirdata = sctx->dirdata;
+
+ if (!dirdata)
+ return 0;
+
+ /*
+ * Impure xattr should be set if directory has redirect/merge
+ * subdir or origin targets.
+ */
+ if (!dirdata->origins && !dirdata->mergedirs &&
+ !dirdata->redirects)
+ return 0;
+
+ if (ovl_is_impure(sctx->dirfd, sctx->pathname))
+ return 0;
+
+ /* Fix impure xattrs */
+ if (ovl_ask_action("Missing impure xattr", sctx->pathname,
+ sctx->dirtype, sctx->stack, "Fix", 1)) {
+ if (ovl_set_impure(sctx->dirfd, sctx->pathname))
+ return -1;
+ } else {
+ /*
+ * Note: not enforce to fix the case of directory that
+ * only contains general merge subdirs because it could
+ * be an newly created overlay image and fix by overlay
+ * filesystem after mount.
+ */
+ if (dirdata->origins || dirdata->redirects)
+ sctx->m_impure++;
+ }
+
+ return 0;
+}
+
static int ovl_count_origin(struct scan_ctx *sctx)
{
struct scan_dir_data *parent = sctx->dirdata;
@@ -760,8 +818,9 @@ static int ovl_count_unreal(struct scan_ctx *sctx)
* of redirect directory, include duplicate redirect
* directory. After this pass, the hierarchical structure
* of each layer's directories becomes consistent.
- * -Pass two: iterate through all directories, and find and check
- * validity of whiteouts.
+ * -Pass two: Iterate through all directories, and find and check
+ * validity of whiteouts, and check missing impure xattr
+ * in upperdir.
*/
static struct scan_operations ovl_scan_ops[OVL_SCAN_PASS][2] = {
@@ -778,6 +837,7 @@ static struct scan_operations ovl_scan_ops[OVL_SCAN_PASS][2] = {
.whiteout = ovl_check_whiteout,
.origin = ovl_count_origin,
.unreal = ovl_count_unreal,
+ .impure = ovl_check_impure,
},
[OVL_LOWER] = {
.whiteout = ovl_check_whiteout,
@@ -787,7 +847,7 @@ static struct scan_operations ovl_scan_ops[OVL_SCAN_PASS][2] = {
static char *ovl_scan_desc[OVL_SCAN_PASS] = {
"Checking redirect xattr and directory tree",
- "Checking whiteouts"
+ "Checking whiteouts and impure xattr"
};
static void ovl_scan_clean(void)
@@ -800,10 +860,12 @@ static void ovl_scan_report(struct scan_ctx *sctx)
{
if (flags & FL_VERBOSE) {
print_info(_("Scan %d directories, %d files, "
- "%d/%d whiteouts, %d/%d redirect dirs\n"),
+ "%d/%d whiteouts, %d/%d redirect dirs "
+ "%d missing impure\n"),
sctx->directories, sctx->files,
sctx->i_whiteouts, sctx->t_whiteouts,
- sctx->i_redirects, sctx->t_redirects);
+ sctx->i_redirects, sctx->t_redirects,
+ sctx->m_impure);
}
}
@@ -815,6 +877,9 @@ static void ovl_scan_check(struct scan_ctx *sctx)
else if (sctx->i_redirects)
print_info(_("Invalid redirect directories %d left!\n"),
sctx->i_redirects);
+ else if (sctx->m_impure)
+ print_info(_("Directories %d missing impure xattr!\n"),
+ sctx->m_impure);
else
return;
@@ -829,7 +894,8 @@ int ovl_scan_fix(void)
int ret;
if (flags & FL_VERBOSE)
- print_info(_("Scan and fix: [whiteouts|redirect dir]\n"));
+ print_info(_("Scan and fix: "
+ "[whiteouts|redirect dir|impure dir]\n"));
for (i = 0; i < OVL_SCAN_PASS; i++) {
if (flags & FL_VERBOSE)
diff --git a/lib.c b/lib.c
index 03bd8eb..19eab65 100644
--- a/lib.c
+++ b/lib.c
@@ -253,6 +253,11 @@ int scan_dir(struct scan_ctx *sctx, struct scan_operations *sop)
sctx->dirdata = 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->dirdata);
sctx->dirdata = ftsent->fts_pointer;
diff --git a/lib.h b/lib.h
index 60e620e..8d1d936 100644
--- a/lib.h
+++ b/lib.h
@@ -55,6 +55,7 @@
#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 structs */
@@ -76,6 +77,7 @@ struct scan_ctx {
int i_whiteouts; /* invalid whiteouts */
int t_redirects; /* total redirect dirs */
int i_redirects; /* invalid redirect dirs */
+ int m_impure; /* missing inpure dirs */
const char *pathname; /* path relative to overlay root */
const char *filename; /* filename */
@@ -89,6 +91,7 @@ struct scan_operations {
int (*redirect)(struct scan_ctx *);
int (*origin)(struct scan_ctx *);
int (*unreal)(struct scan_ctx *);
+ int (*impure)(struct scan_ctx *);
};
static inline void set_inconsistency(int *status)
--
2.9.5
--
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