For stat(2) on lowerdir non-dir entries in non-samefs case, this commit
provides unique values for st_dev. The unique values are obtained by
allocating anonymous bdevs for each of the lowerdirs in the overlayfs
instance.
Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
---
Changelog:
v2->v3: Optimize away O(n) search for pseudo dev in ovl_get_pseudo_dev().
v1->v2: Drop code that provided unique st_dev across copy up.
fs/overlayfs/copy_up.c | 1 -
fs/overlayfs/inode.c | 18 +++++++++++++
fs/overlayfs/namei.c | 37 +++++++++++++-------------
fs/overlayfs/overlayfs.h | 5 ++--
fs/overlayfs/ovl_entry.h | 14 ++++++++--
fs/overlayfs/readdir.c | 4 +--
fs/overlayfs/super.c | 69 ++++++++++++++++++++++++++++++------------------
fs/overlayfs/util.c | 8 ++++--
8 files changed, 102 insertions(+), 54 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index f193976..fc27f92 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -22,7 +22,6 @@
#include <linux/ratelimit.h>
#include <linux/exportfs.h>
#include "overlayfs.h"
-#include "ovl_entry.h"
#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 69f4fc2..8e81aa7 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -8,6 +8,7 @@
*/
#include <linux/fs.h>
+#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/xattr.h>
@@ -15,6 +16,21 @@
#include <linux/ratelimit.h>
#include "overlayfs.h"
+
+static dev_t ovl_get_pseudo_dev(struct dentry *dentry, dev_t dev)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb->s_dev == dev)
+ return dev;
+
+ if (oe->numlower)
+ return oe->lowerstack[0].layer->pseudo_dev;
+
+ return dev;
+}
+
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
int err;
@@ -121,6 +137,8 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
*/
stat->dev = dentry->d_sb->s_dev;
stat->ino = dentry->d_inode->i_ino;
+ } else {
+ stat->dev = ovl_get_pseudo_dev(dentry, stat->dev);
}
/*
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 9bc0e58..c286719 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -15,7 +15,6 @@
#include <linux/mount.h>
#include <linux/exportfs.h>
#include "overlayfs.h"
-#include "ovl_entry.h"
struct ovl_lookup_data {
struct qstr name;
@@ -286,16 +285,15 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
static int ovl_check_origin(struct dentry *upperdentry,
- struct path *lowerstack, unsigned int numlower,
- struct path **stackp, unsigned int *ctrp)
+ struct ovl_lower *lower, unsigned int numlower,
+ struct ovl_lower **stackp, unsigned int *ctrp)
{
struct vfsmount *mnt;
struct dentry *origin = NULL;
int i;
-
for (i = 0; i < numlower; i++) {
- mnt = lowerstack[i].mnt;
+ mnt = lower[i].layer->mnt;
origin = ovl_get_origin(upperdentry, mnt);
if (IS_ERR(origin))
return PTR_ERR(origin);
@@ -309,12 +307,12 @@ static int ovl_check_origin(struct dentry *upperdentry,
BUG_ON(*ctrp);
if (!*stackp)
- *stackp = kmalloc(sizeof(struct path), GFP_TEMPORARY);
+ *stackp = kmalloc(sizeof(struct ovl_lower), GFP_TEMPORARY);
if (!*stackp) {
dput(origin);
return -ENOMEM;
}
- **stackp = (struct path) { .dentry = origin, .mnt = mnt };
+ **stackp = (struct ovl_lower) { .dentry = origin, .layer = lower[i].layer };
*ctrp = 1;
return 0;
@@ -384,13 +382,13 @@ int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
* OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
* Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
*/
-int ovl_verify_index(struct dentry *index, struct path *lowerstack,
+int ovl_verify_index(struct dentry *index, struct ovl_lower *lower,
unsigned int numlower)
{
struct ovl_fh *fh = NULL;
size_t len;
- struct path origin = { };
- struct path *stack = &origin;
+ struct ovl_lower origin = { };
+ struct ovl_lower *stack = &origin;
unsigned int ctr = 0;
int err;
@@ -419,7 +417,7 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack,
if (err)
goto fail;
- err = ovl_check_origin(index, lowerstack, numlower, &stack, &ctr);
+ err = ovl_check_origin(index, lower, numlower, &stack, &ctr);
if (!err && !ctr)
err = -ESTALE;
if (err)
@@ -545,7 +543,8 @@ int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
idx++;
}
BUG_ON(idx > oe->numlower);
- *path = oe->lowerstack[idx - 1];
+ path->dentry = oe->lowerstack[idx - 1].dentry;
+ path->mnt = oe->lowerstack[idx - 1].layer->mnt;
return (idx < oe->numlower) ? idx + 1 : -1;
}
@@ -558,7 +557,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
- struct path *stack = NULL;
+ struct ovl_lower *stack = NULL;
struct dentry *upperdir, *upperdentry = NULL;
struct dentry *index = NULL;
unsigned int ctr = 0;
@@ -622,17 +621,17 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (!d.stop && poe->numlower) {
err = -ENOMEM;
- stack = kcalloc(ofs->numlower, sizeof(struct path),
+ stack = kcalloc(ofs->numlower, sizeof(struct ovl_lower),
GFP_TEMPORARY);
if (!stack)
goto out_put_upper;
}
for (i = 0; !d.stop && i < poe->numlower; i++) {
- struct path lowerpath = poe->lowerstack[i];
+ struct ovl_lower lower = poe->lowerstack[i];
d.last = i == poe->numlower - 1;
- err = ovl_lookup_layer(lowerpath.dentry, &d, &this);
+ err = ovl_lookup_layer(lower.dentry, &d, &this);
if (err)
goto out_put;
@@ -640,7 +639,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
continue;
stack[ctr].dentry = this;
- stack[ctr].mnt = lowerpath.mnt;
+ stack[ctr].layer = lower.layer;
ctr++;
if (d.stop)
@@ -651,7 +650,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
/* Find the current layer on the root dentry */
for (i = 0; i < poe->numlower; i++)
- if (poe->lowerstack[i].mnt == lowerpath.mnt)
+ if (poe->lowerstack[i].layer->mnt == lower.layer->mnt)
break;
if (WARN_ON(i == poe->numlower))
break;
@@ -676,7 +675,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
goto out_put;
oe->opaque = upperopaque;
- memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
+ memcpy(oe->lowerstack, stack, sizeof(struct ovl_lower) * ctr);
dentry->d_fsdata = oe;
if (upperdentry)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 60d2660..76856dc 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -9,6 +9,7 @@
#include <linux/kernel.h>
#include <linux/uuid.h>
+#include "ovl_entry.h"
enum ovl_path_type {
__OVL_PATH_UPPER = (1 << 0),
@@ -242,7 +243,7 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
/* namei.c */
int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
struct dentry *origin, bool is_upper, bool set);
-int ovl_verify_index(struct dentry *index, struct path *lowerstack,
+int ovl_verify_index(struct dentry *index, struct ovl_lower *lower,
unsigned int numlower);
int ovl_get_index_name(struct dentry *origin, struct qstr *name);
int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
@@ -258,7 +259,7 @@ int ovl_check_d_type_supported(struct path *realpath);
void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
struct dentry *dentry, int level);
int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
- struct path *lowerstack, unsigned int numlower);
+ struct ovl_lower *lower, unsigned int numlower);
/* inode.c */
int ovl_set_nlink_upper(struct dentry *dentry);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 878a750..c2d9322 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -17,11 +17,21 @@ struct ovl_config {
bool index;
};
+struct ovl_lower_mnt {
+ struct vfsmount *mnt;
+ dev_t pseudo_dev;
+};
+
+struct ovl_lower {
+ struct ovl_lower_mnt *layer;
+ struct dentry *dentry;
+};
+
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
unsigned numlower;
- struct vfsmount **lower_mnt;
+ struct ovl_lower_mnt *lower_mnt;
/* workbasedir is the path at workdir= mount option */
struct dentry *workbasedir;
/* workdir is the 'work' directory under workbasedir */
@@ -49,7 +59,7 @@ struct ovl_entry {
struct rcu_head rcu;
};
unsigned numlower;
- struct path lowerstack[];
+ struct ovl_lower lowerstack[];
};
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 0298463..f286c32 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -669,7 +669,7 @@ void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
}
int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
- struct path *lowerstack, unsigned int numlower)
+ struct ovl_lower *lower, unsigned int numlower)
{
int err;
struct inode *dir = dentry->d_inode;
@@ -703,7 +703,7 @@ int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
err = PTR_ERR(index);
break;
}
- if (ovl_verify_index(index, lowerstack, numlower)) {
+ if (ovl_verify_index(index, lower, numlower)) {
err = ovl_cleanup(dir, index);
if (err)
break;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 44dc2d6..ae0e034 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -18,7 +18,6 @@
#include <linux/seq_file.h>
#include <linux/posix_acl_xattr.h>
#include "overlayfs.h"
-#include "ovl_entry.h"
MODULE_AUTHOR("Miklos Szeredi <miklos@xxxxxxxxxx>");
MODULE_DESCRIPTION("Overlay filesystem");
@@ -215,8 +214,10 @@ static void ovl_put_super(struct super_block *sb)
if (ufs->upper_mnt)
ovl_inuse_unlock(ufs->upper_mnt->mnt_root);
mntput(ufs->upper_mnt);
- for (i = 0; i < ufs->numlower; i++)
- mntput(ufs->lower_mnt[i]);
+ for (i = 0; i < ufs->numlower; i++) {
+ mntput(ufs->lower_mnt[i].mnt);
+ free_anon_bdev(ufs->lower_mnt[i].pseudo_dev);
+ }
kfree(ufs->lower_mnt);
kfree(ufs->config.lowerdir);
@@ -1014,15 +1015,25 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
err = -ENOMEM;
- ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
+ ufs->lower_mnt = kcalloc(numlower, sizeof(struct ovl_lower_mnt),
+ GFP_KERNEL);
if (ufs->lower_mnt == NULL)
goto out_put_workdir;
for (i = 0; i < numlower; i++) {
- struct vfsmount *mnt = clone_private_mount(&stack[i]);
+ struct vfsmount *mnt;
+ dev_t dev;
+
+ err = get_anon_bdev(&dev);
+ if (err) {
+ pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
+ goto out_put_lower_mnt;
+ }
+ mnt = clone_private_mount(&stack[i]);
err = PTR_ERR(mnt);
if (IS_ERR(mnt)) {
pr_err("overlayfs: failed to clone lowerpath\n");
+ free_anon_bdev(dev);
goto out_put_lower_mnt;
}
/*
@@ -1031,7 +1042,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
*/
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
- ufs->lower_mnt[ufs->numlower] = mnt;
+ ufs->lower_mnt[ufs->numlower].mnt = mnt;
+ ufs->lower_mnt[ufs->numlower].pseudo_dev = dev;
ufs->numlower++;
/* Check if all lower layers are on same sb */
@@ -1047,20 +1059,30 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
else if (ufs->upper_mnt->mnt_sb != ufs->same_sb)
ufs->same_sb = NULL;
+ err = -ENOMEM;
+ oe = ovl_alloc_entry(numlower);
+ if (!oe)
+ goto out_put_lower_mnt;
+
+ for (i = 0; i < numlower; i++) {
+ oe->lowerstack[i].dentry = stack[i].dentry;
+ oe->lowerstack[i].layer = &(ufs->lower_mnt[i]);
+ }
+
if (!(ovl_force_readonly(ufs)) && ufs->config.index) {
/* Verify lower root is upper root origin */
- err = ovl_verify_origin(upperpath.dentry, ufs->lower_mnt[0],
- stack[0].dentry, false, true);
+ err = ovl_verify_origin(upperpath.dentry, oe->lowerstack[0].layer->mnt,
+ oe->lowerstack[0].dentry, false, true);
if (err) {
pr_err("overlayfs: failed to verify upper root origin\n");
- goto out_put_lower_mnt;
+ goto out_free_oe;
}
ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry,
OVL_INDEXDIR_NAME, true);
err = PTR_ERR(ufs->indexdir);
if (IS_ERR(ufs->indexdir))
- goto out_put_lower_mnt;
+ goto out_free_oe;
if (ufs->indexdir) {
/* Verify upper root is index dir origin */
@@ -1073,7 +1095,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (!err)
err = ovl_indexdir_cleanup(ufs->indexdir,
ufs->upper_mnt,
- stack, numlower);
+ oe->lowerstack,
+ numlower);
}
if (err || !ufs->indexdir)
pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
@@ -1097,11 +1120,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
/* Never override disk quota limits or use reserved space */
cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
- err = -ENOMEM;
- oe = ovl_alloc_entry(numlower);
- if (!oe)
- goto out_put_cred;
-
sb->s_magic = OVERLAYFS_SUPER_MAGIC;
sb->s_op = &ovl_super_operations;
sb->s_xattr = ovl_xattr_handlers;
@@ -1110,11 +1128,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
if (!root_dentry)
- goto out_free_oe;
+ goto out_put_cred;
mntput(upperpath.mnt);
for (i = 0; i < numlower; i++)
mntput(stack[i].mnt);
+ kfree(stack);
mntput(workpath.mnt);
kfree(lowertmp);
@@ -1123,11 +1142,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (ovl_is_impuredir(upperpath.dentry))
ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));
}
- for (i = 0; i < numlower; i++) {
- oe->lowerstack[i].dentry = stack[i].dentry;
- oe->lowerstack[i].mnt = ufs->lower_mnt[i];
- }
- kfree(stack);
root_dentry->d_fsdata = oe;
@@ -1138,15 +1152,18 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
return 0;
-out_free_oe:
- kfree(oe);
out_put_cred:
put_cred(ufs->creator_cred);
out_put_indexdir:
dput(ufs->indexdir);
+out_free_oe:
+ kfree(oe);
out_put_lower_mnt:
- for (i = 0; i < ufs->numlower; i++)
- mntput(ufs->lower_mnt[i]);
+ for (i = 0; i < ufs->numlower; i++) {
+ if (ufs->lower_mnt[i].mnt)
+ free_anon_bdev(ufs->lower_mnt[i].pseudo_dev);
+ mntput(ufs->lower_mnt[i].mnt);
+ }
kfree(ufs->lower_mnt);
out_put_workdir:
dput(ufs->workdir);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index c492ba7..b16aade 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -17,7 +17,6 @@
#include <linux/namei.h>
#include <linux/ratelimit.h>
#include "overlayfs.h"
-#include "ovl_entry.h"
int ovl_want_write(struct dentry *dentry)
{
@@ -125,7 +124,12 @@ void ovl_path_lower(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
- *path = oe->numlower ? oe->lowerstack[0] : (struct path) { };
+ if (oe->numlower) {
+ path->mnt = oe->lowerstack[0].layer->mnt;
+ path->dentry = oe->lowerstack[0].dentry;
+ } else {
+ *path = (struct path) { };
+ }
}
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
--
2.9.3
--
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