#include <linux/cred.h>
#include <linux/xattr.h>
#include <linux/posix_acl.h>
+#include <linux/ratelimit.h>
#include "overlayfs.h"
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
WARN_ON_ONCE(stat->dev != lowerstat.dev);
/*
- * Lower hardlinks are broken on copy up to different
+ * Lower hardlinks may be broken on copy up to different
* upper files, so we cannot use the lower origin st_ino
* for those different files, even for the same fs case.
+ * With inodes index enabled, it is safe to use st_ino
+ * of an indexed hardlinked origin. The index validates
+ * that the upper hardlink is not broken.
*/
- if (is_dir || lowerstat.nlink == 1)
+ if (is_dir || lowerstat.nlink == 1 ||
+ ovl_test_flag(OVL_INDEX, d_inode(dentry)))
stat->ino = lowerstat.ino;
}
stat->dev = dentry->d_sb->s_dev;
if (is_dir && OVL_TYPE_MERGE(type))
stat->nlink = 1;
+ /*
+ * Return the overlay inode nlinks for indexed upper inodes.
+ * Overlay inode nlink counts the union of the upper hardlinks
+ * and non-covered lower hardlinks. It does not include the upper
+ * index hardlink.
+ */
+ if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+ stat->nlink = dentry->d_inode->i_nlink;
+
out:
revert_creds(old_cred);
int ovl_permission(struct inode *inode, int mask)
{
- bool is_upper;
- struct inode *realinode = ovl_inode_real(inode, &is_upper);
+ struct inode *upperinode = ovl_inode_upper(inode);
+ struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
const struct cred *old_cred;
int err;
return err;
old_cred = ovl_override_creds(inode->i_sb);
- if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) {
+ if (!upperinode &&
+ !special_file(realinode->i_mode) && mask & MAY_WRITE) {
mask &= ~(MAY_WRITE | MAY_APPEND);
/* Make sure mounter can read file for copy up later */
mask |= MAY_READ;
sizeof(OVL_XATTR_PREFIX) - 1) == 0;
}
-int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,
- size_t size, int flags)
+int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
+ const void *value, size_t size, int flags)
{
int err;
- struct path realpath;
- enum ovl_path_type type = ovl_path_real(dentry, &realpath);
+ struct dentry *upperdentry = ovl_i_dentry_upper(inode);
+ struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
const struct cred *old_cred;
err = ovl_want_write(dentry);
if (err)
goto out;
- if (!value && !OVL_TYPE_UPPER(type)) {
- err = vfs_getxattr(realpath.dentry, name, NULL, 0);
+ if (!value && !upperdentry) {
+ err = vfs_getxattr(realdentry, name, NULL, 0);
if (err < 0)
goto out_drop_write;
}
- err = ovl_copy_up(dentry);
- if (err)
- goto out_drop_write;
+ if (!upperdentry) {
+ err = ovl_copy_up(dentry);
+ if (err)
+ goto out_drop_write;
- if (!OVL_TYPE_UPPER(type))
- ovl_path_upper(dentry, &realpath);
+ realdentry = ovl_dentry_upper(dentry);
+ }
old_cred = ovl_override_creds(dentry->d_sb);
if (value)
- err = vfs_setxattr(realpath.dentry, name, value, size, flags);
+ err = vfs_setxattr(realdentry, name, value, size, flags);
else {
WARN_ON(flags != XATTR_REPLACE);
- err = vfs_removexattr(realpath.dentry, name);
+ err = vfs_removexattr(realdentry, name);
}
revert_creds(old_cred);
return err;
}
-int ovl_xattr_get(struct dentry *dentry, const char *name,
+int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
void *value, size_t size)
{
- struct dentry *realdentry = ovl_dentry_real(dentry);
ssize_t res;
const struct cred *old_cred;
+ struct dentry *realdentry =
+ ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);
old_cred = ovl_override_creds(dentry->d_sb);
res = vfs_getxattr(realdentry, name, value, size);
struct posix_acl *ovl_get_acl(struct inode *inode, int type)
{
- struct inode *realinode = ovl_inode_real(inode, NULL);
+ struct inode *realinode = ovl_inode_real(inode);
const struct cred *old_cred;
struct posix_acl *acl;
return acl;
}
-static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
- struct dentry *realdentry)
+static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
{
- if (OVL_TYPE_UPPER(type))
+ if (ovl_dentry_upper(dentry) &&
+ ovl_dentry_has_upper_alias(dentry))
return false;
- if (special_file(realdentry->d_inode->i_mode))
+ if (special_file(d_inode(dentry)->i_mode))
return false;
if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
{
int err = 0;
- struct path realpath;
- enum ovl_path_type type;
- type = ovl_path_real(dentry, &realpath);
- if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
+ if (ovl_open_need_copy_up(dentry, file_flags)) {
err = ovl_want_write(dentry);
if (!err) {
err = ovl_copy_up_flags(dentry, file_flags);
}
}
+/*
+ * With inodes index enabled, an overlay inode nlink counts the union of upper
+ * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure
+ * upper inode, the following nlink modifying operations can happen:
+ *
+ * 1. Lower hardlink copy up
+ * 2. Upper hardlink created, unlinked or renamed over
+ * 3. Lower hardlink whiteout or renamed over
+ *
+ * For the first, copy up case, the union nlink does not change, whether the
+ * operation succeeds or fails, but the upper inode nlink may change.
+ * Therefore, before copy up, we store the union nlink value relative to the
+ * lower inode nlink in the index inode xattr trusted.overlay.nlink.
+ *
+ * For the second, upper hardlink case, the union nlink should be incremented
+ * or decremented IFF the operation succeeds, aligned with nlink change of the
+ * upper inode. Therefore, before link/unlink/rename, we store the union nlink
+ * value relative to the upper inode nlink in the index inode.
+ *
+ * For the last, lower cover up case, we simplify things by preceding the
+ * whiteout or cover up with copy up. This makes sure that there is an index
+ * upper inode where the nlink xattr can be stored before the copied up upper
+ * entry is unlink.
+ */
+#define OVL_NLINK_ADD_UPPER (1 << 0)
+
+/*
+ * On-disk format for indexed nlink:
+ *
+ * nlink relative to the upper inode - "U[+-]NUM"
+ * nlink relative to the lower inode - "L[+-]NUM"
+ */
+
+static int ovl_set_nlink_common(struct dentry *dentry,
+ struct dentry *realdentry, const char *format)
+{
+ struct inode *inode = d_inode(dentry);
+ struct inode *realinode = d_inode(realdentry);
+ char buf[13];
+ int len;
+
+ len = snprintf(buf, sizeof(buf), format,
+ (int) (inode->i_nlink - realinode->i_nlink));
+
+ if (WARN_ON(len >= sizeof(buf)))
+ return -EIO;
+
+ return ovl_do_setxattr(ovl_dentry_upper(dentry),
+ OVL_XATTR_NLINK, buf, len, 0);
+}
+
+int ovl_set_nlink_upper(struct dentry *dentry)
+{
+ return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i");
+}
+
+int ovl_set_nlink_lower(struct dentry *dentry)
+{
+ return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i");
+}
+
+unsigned int ovl_get_nlink(struct dentry *lowerdentry,
+ struct dentry *upperdentry,
+ unsigned int fallback)
+{
+ int nlink_diff;
+ int nlink;
+ char buf[13];
+ int err;
+
+ if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
+ return fallback;
+
+ err = vfs_getxattr(upperdentry, OVL_XATTR_NLINK, &buf, sizeof(buf) - 1);
+ if (err < 0)
+ goto fail;
+
+ buf[err] = '\0';
+ if ((buf[0] != 'L' && buf[0] != 'U') ||
+ (buf[1] != '+' && buf[1] != '-'))
+ goto fail;
+
+ err = kstrtoint(buf + 1, 10, &nlink_diff);
+ if (err < 0)
+ goto fail;
+
+ nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
+ nlink += nlink_diff;
+
+ if (nlink <= 0)
+ goto fail;
+
+ return nlink;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n",
+ upperdentry, err);
+ return fallback;
+}
+
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev)
{
struct inode *inode;
static int ovl_inode_test(struct inode *inode, void *data)
{
- return ovl_inode_real(inode, NULL) == data;
+ return inode->i_private == data;
}
static int ovl_inode_set(struct inode *inode, void *data)
{
- inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK);
+ inode->i_private = data;
return 0;
}
-struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode)
+static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
+ struct dentry *upperdentry)
+{
+ /*
+ * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
+ * This happens when finding a copied up overlay inode for a renamed
+ * or hardlinked overlay dentry and lower dentry cannot be followed
+ * by origin because lower fs does not support file handles.
+ */
+ if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
+ return false;
+ /*
+ * Allow non-NULL __upperdentry in inode even if upperdentry is NULL.
+ * This happens when finding a lower alias for a copied up hard link.
+ */
+ if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry))
+ return false;
+
+ return true;
+}
+
+struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry)
{
+ struct dentry *lowerdentry = ovl_dentry_lower(dentry);
+ struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
struct inode *inode;
- inode = iget5_locked(sb, (unsigned long) realinode,
- ovl_inode_test, ovl_inode_set, realinode);
- if (inode && inode->i_state & I_NEW) {
- ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);
- set_nlink(inode, realinode->i_nlink);
- unlock_new_inode(inode);
+ if (!realinode)
+ realinode = d_inode(lowerdentry);
+
+ if (!S_ISDIR(realinode->i_mode) &&
+ (upperdentry || (lowerdentry && ovl_indexdir(dentry->d_sb)))) {
+ struct inode *key = d_inode(lowerdentry ?: upperdentry);
+ unsigned int nlink;
+
+ inode = iget5_locked(dentry->d_sb, (unsigned long) key,
+ ovl_inode_test, ovl_inode_set, key);
+ if (!inode)
+ goto out_nomem;
+ if (!(inode->i_state & I_NEW)) {
+ /*
+ * Verify that the underlying files stored in the inode
+ * match those in the dentry.
+ */
+ if (!ovl_verify_inode(inode, lowerdentry, upperdentry)) {
+ iput(inode);
+ inode = ERR_PTR(-ESTALE);
+ goto out;
+ }
+
+ dput(upperdentry);
+ goto out;
+ }
+
+ nlink = ovl_get_nlink(lowerdentry, upperdentry,
+ realinode->i_nlink);
+ set_nlink(inode, nlink);
+ } else {
+ inode = new_inode(dentry->d_sb);
+ if (!inode)
+ goto out_nomem;
}
+ ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);
+ ovl_inode_init(inode, upperdentry, lowerdentry);
+ if (upperdentry && ovl_is_impuredir(upperdentry))
+ ovl_set_flag(OVL_IMPURE, inode);
+
+ if (inode->i_state & I_NEW)
+ unlock_new_inode(inode);
+out:
return inode;
+
+out_nomem:
+ inode = ERR_PTR(-ENOMEM);
+ goto out;
}
git.samba.org / sfrench / cifs-2.6.git / blobdiff