In order to help check any dirs has been used in overlay, add share
flock to lowerdirs/upperdir/workdir, so user space can use flock -x to
help check mount.
Signed-off-by: yangerkun <yangerkun@xxxxxxxxxx>
---
fs/overlayfs/ovl_entry.h | 3 ++
fs/overlayfs/super.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 90 insertions(+)
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index bfef6ed..69dd89c 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -35,10 +35,13 @@ struct ovl_path {
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
+ struct file *upperfile;
unsigned numlower;
struct ovl_layer *lower_layers;
+ struct file **lowerfiles;
/* workbasedir is the path at workdir= mount option */
struct dentry *workbasedir;
+ struct file *workbasefile;
/* workdir is the 'work' directory under workbasedir */
struct dentry *workdir;
/* index directory listing overlay inodes by origin file handle */
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 9ee37c7..e311c66 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/statfs.h>
#include <linux/seq_file.h>
+#include <linux/file.h>
#include <linux/posix_acl_xattr.h>
#include "overlayfs.h"
@@ -233,15 +234,31 @@ static void ovl_free_fs(struct ovl_fs *ofs)
if (ofs->workdir_locked)
ovl_inuse_unlock(ofs->workbasedir);
dput(ofs->workbasedir);
+
+ if (ofs->workbasefile)
+ fput(ofs->workbasefile);
+
if (ofs->upperdir_locked)
ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
mntput(ofs->upper_mnt);
+
+ if (ofs->upperfile)
+ fput(ofs->upperfile);
+
for (i = 0; i < ofs->numlower; i++) {
mntput(ofs->lower_layers[i].mnt);
free_anon_bdev(ofs->lower_layers[i].pseudo_dev);
}
kfree(ofs->lower_layers);
+ if (ofs->lowerfiles) {
+ for (i = 0; i < ofs->numlower; i++) {
+ if (ofs->lowerfiles[i])
+ fput(ofs->lowerfiles[i]);
+ }
+ kfree(ofs->lowerfiles);
+ }
+
kfree(ofs->config.lowerdir);
kfree(ofs->config.upperdir);
kfree(ofs->config.workdir);
@@ -902,15 +919,49 @@ static int ovl_other_xattr_set(const struct xattr_handler *handler,
NULL
};
+static int ovl_add_share_flock(struct file *filp)
+{
+ int err;
+ struct file_lock *fl = locks_alloc_lock();
+
+ if (!fl)
+ return -ENOMEM;
+ fl->fl_file = filp;
+ fl->fl_owner = filp;
+ fl->fl_pid = current->tgid;
+ fl->fl_flags = FL_FLOCK;
+ fl->fl_type = F_RDLCK;
+ fl->fl_end = OFFSET_MAX;
+
+ err = flock_setlk(filp, fl);
+ locks_free_lock(fl);
+ return err;
+}
+
static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)
{
struct vfsmount *upper_mnt;
+ struct file *upperfile;
int err;
err = ovl_mount_dir(ofs->config.upperdir, upperpath);
if (err)
goto out;
+ upperfile = ovl_path_open(upperpath, O_DIRECTORY);
+ if (IS_ERR(upperfile)) {
+ pr_err("overlayfs: unable to open upperdir.\n");
+ err = PTR_ERR(upperfile);
+ goto out;
+ }
+
+ ofs->upperfile = upperfile;
+ err = ovl_add_share_flock(upperfile);
+ if (err) {
+ pr_err("overlayfs: unable to add share flock for upperdir.\n");
+ goto out;
+ }
+
/* Upper fs should not be r/o */
if (sb_rdonly(upperpath->mnt->mnt_sb)) {
pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
@@ -1021,11 +1072,26 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
{
int err;
struct path workpath = { };
+ struct file *workfile;
err = ovl_mount_dir(ofs->config.workdir, &workpath);
if (err)
goto out;
+ workfile = ovl_path_open(&workpath, O_DIRECTORY);
+ if (IS_ERR(workfile)) {
+ pr_err("overlayfs: unable to open workdir.\n");
+ err = PTR_ERR(workfile);
+ goto out;
+ }
+
+ ofs->workbasefile = workfile;
+ err = ovl_add_share_flock(workfile);
+ if (err) {
+ pr_err("overlayfs: unable to add share flock for workdir.\n");
+ goto out;
+ }
+
err = -EINVAL;
if (upperpath->mnt != workpath.mnt) {
pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
@@ -1167,6 +1233,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
unsigned int stacklen, numlower = 0, i;
bool remote = false;
struct ovl_entry *oe;
+ struct file *lowerfile, **files = NULL;
err = -ENOMEM;
lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
@@ -1193,6 +1260,10 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
if (!stack)
goto out_err;
+ files = kcalloc(stacklen, sizeof(struct file *), GFP_KERNEL);
+ if (!files)
+ goto out_err;
+
err = -EINVAL;
lower = lowertmp;
for (numlower = 0; numlower < stacklen; numlower++) {
@@ -1201,9 +1272,24 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
if (err)
goto out_err;
+ lowerfile = ovl_path_open(&stack[numlower], O_DIRECTORY);
+ if (IS_ERR(lowerfile)) {
+ pr_err("overlayfs: unable to open lowerdir:%s.\n", lower);
+ goto out_err;
+ }
+
+ files[numlower] = lowerfile;
+ err = ovl_add_share_flock(lowerfile);
+ if (err) {
+ pr_err("overlayfs: unable to add share flock for lowerdir:%s.\n", lower);
+ goto out_err;
+ }
+
lower = strchr(lower, '\0') + 1;
}
+ ofs->lowerfiles = files;
+
err = -EINVAL;
sb->s_stack_depth++;
if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
@@ -1239,6 +1325,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
return oe;
out_err:
+ kfree(files);
oe = ERR_PTR(err);
goto out;
}
--
1.8.3.1
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