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locks: break delegations on any attribute modification

NFSv4 uses leases to guarantee that clients can cache metadata as well
as data.

Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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1 parent 146a859 commit 27ac0ffeac80ba6b9580529568d06144df044366 J. Bruce Fields committed with Al Viro Sep 20, 2011
Showing with 69 additions and 17 deletions.
  1. +2 −2 drivers/base/devtmpfs.c
  2. +24 −1 fs/attr.c
  3. +2 −2 fs/cachefiles/interface.c
  4. +2 −2 fs/ecryptfs/inode.c
  5. +1 −1 fs/hpfs/namei.c
  6. +5 −1 fs/inode.c
  7. +6 −2 fs/nfsd/vfs.c
  8. +18 −4 fs/open.c
  9. +8 −1 fs/utimes.c
  10. +1 −1 include/linux/fs.h
@@ -216,7 +216,7 @@ static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
newattrs.ia_gid = gid;
newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
mutex_lock(&dentry->d_inode->i_mutex);
- notify_change(dentry, &newattrs);
+ notify_change(dentry, &newattrs, NULL);
mutex_unlock(&dentry->d_inode->i_mutex);
/* mark as kernel-created inode */
@@ -322,7 +322,7 @@ static int handle_remove(const char *nodename, struct device *dev)
newattrs.ia_valid =
ATTR_UID|ATTR_GID|ATTR_MODE;
mutex_lock(&dentry->d_inode->i_mutex);
- notify_change(dentry, &newattrs);
+ notify_change(dentry, &newattrs, NULL);
mutex_unlock(&dentry->d_inode->i_mutex);
err = vfs_unlink(parent.dentry->d_inode, dentry, NULL);
if (!err || err == -ENOENT)
View
@@ -167,7 +167,27 @@ void setattr_copy(struct inode *inode, const struct iattr *attr)
}
EXPORT_SYMBOL(setattr_copy);
-int notify_change(struct dentry * dentry, struct iattr * attr)
+/**
+ * notify_change - modify attributes of a filesytem object
+ * @dentry: object affected
+ * @iattr: new attributes
+ * @delegated_inode: returns inode, if the inode is delegated
+ *
+ * The caller must hold the i_mutex on the affected object.
+ *
+ * If notify_change discovers a delegation in need of breaking,
+ * it will return -EWOULDBLOCK and return a reference to the inode in
+ * delegated_inode. The caller should then break the delegation and
+ * retry. Because breaking a delegation may take a long time, the
+ * caller should drop the i_mutex before doing so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode. This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported. Also, passing NULL is fine for callers holding
+ * the file open for write, as there can be no conflicting delegation in
+ * that case.
+ */
+int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode)
{
struct inode *inode = dentry->d_inode;
umode_t mode = inode->i_mode;
@@ -243,6 +263,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
error = security_inode_setattr(dentry, attr);
if (error)
return error;
+ error = try_break_deleg(inode, delegated_inode);
+ if (error)
+ return error;
if (inode->i_op->setattr)
error = inode->i_op->setattr(dentry, attr);
@@ -449,14 +449,14 @@ static int cachefiles_attr_changed(struct fscache_object *_object)
_debug("discard tail %llx", oi_size);
newattrs.ia_valid = ATTR_SIZE;
newattrs.ia_size = oi_size & PAGE_MASK;
- ret = notify_change(object->backer, &newattrs);
+ ret = notify_change(object->backer, &newattrs, NULL);
if (ret < 0)
goto truncate_failed;
}
newattrs.ia_valid = ATTR_SIZE;
newattrs.ia_size = ni_size;
- ret = notify_change(object->backer, &newattrs);
+ ret = notify_change(object->backer, &newattrs, NULL);
truncate_failed:
mutex_unlock(&object->backer->d_inode->i_mutex);
View
@@ -882,7 +882,7 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
mutex_lock(&lower_dentry->d_inode->i_mutex);
- rc = notify_change(lower_dentry, &lower_ia);
+ rc = notify_change(lower_dentry, &lower_ia, NULL);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
}
return rc;
@@ -983,7 +983,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
lower_ia.ia_valid &= ~ATTR_MODE;
mutex_lock(&lower_dentry->d_inode->i_mutex);
- rc = notify_change(lower_dentry, &lower_ia);
+ rc = notify_change(lower_dentry, &lower_ia, NULL);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
fsstack_copy_attr_all(inode, lower_inode);
View
@@ -407,7 +407,7 @@ static int hpfs_unlink(struct inode *dir, struct dentry *dentry)
/*printk("HPFS: truncating file before delete.\n");*/
newattrs.ia_size = 0;
newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
- err = notify_change(dentry, &newattrs);
+ err = notify_change(dentry, &newattrs, NULL);
put_write_access(inode);
if (!err)
goto again;
View
@@ -1603,7 +1603,11 @@ static int __remove_suid(struct dentry *dentry, int kill)
struct iattr newattrs;
newattrs.ia_valid = ATTR_FORCE | kill;
- return notify_change(dentry, &newattrs);
+ /*
+ * Note we call this on write, so notify_change will not
+ * encounter any conflicting delegations:
+ */
+ return notify_change(dentry, &newattrs, NULL);
}
int file_remove_suid(struct file *file)
View
@@ -427,7 +427,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
goto out_nfserr;
fh_lock(fhp);
- host_err = notify_change(dentry, iap);
+ host_err = notify_change(dentry, iap, NULL);
err = nfserrno(host_err);
fh_unlock(fhp);
}
@@ -988,7 +988,11 @@ static void kill_suid(struct dentry *dentry)
ia.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
mutex_lock(&dentry->d_inode->i_mutex);
- notify_change(dentry, &ia);
+ /*
+ * Note we call this on write, so notify_change will not
+ * encounter any conflicting delegations:
+ */
+ notify_change(dentry, &ia, NULL);
mutex_unlock(&dentry->d_inode->i_mutex);
}
View
@@ -57,7 +57,8 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
newattrs.ia_valid |= ret | ATTR_FORCE;
mutex_lock(&dentry->d_inode->i_mutex);
- ret = notify_change(dentry, &newattrs);
+ /* Note any delegations or leases have already been broken: */
+ ret = notify_change(dentry, &newattrs, NULL);
mutex_unlock(&dentry->d_inode->i_mutex);
return ret;
}
@@ -464,21 +465,28 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
static int chmod_common(struct path *path, umode_t mode)
{
struct inode *inode = path->dentry->d_inode;
+ struct inode *delegated_inode = NULL;
struct iattr newattrs;
int error;
error = mnt_want_write(path->mnt);
if (error)
return error;
+retry_deleg:
mutex_lock(&inode->i_mutex);
error = security_path_chmod(path, mode);
if (error)
goto out_unlock;
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
- error = notify_change(path->dentry, &newattrs);
+ error = notify_change(path->dentry, &newattrs, &delegated_inode);
out_unlock:
mutex_unlock(&inode->i_mutex);
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry_deleg;
+ }
mnt_drop_write(path->mnt);
return error;
}
@@ -522,6 +530,7 @@ SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
static int chown_common(struct path *path, uid_t user, gid_t group)
{
struct inode *inode = path->dentry->d_inode;
+ struct inode *delegated_inode = NULL;
int error;
struct iattr newattrs;
kuid_t uid;
@@ -546,12 +555,17 @@ static int chown_common(struct path *path, uid_t user, gid_t group)
if (!S_ISDIR(inode->i_mode))
newattrs.ia_valid |=
ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
+retry_deleg:
mutex_lock(&inode->i_mutex);
error = security_path_chown(path, uid, gid);
if (!error)
- error = notify_change(path->dentry, &newattrs);
+ error = notify_change(path->dentry, &newattrs, &delegated_inode);
mutex_unlock(&inode->i_mutex);
-
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry_deleg;
+ }
return error;
}
View
@@ -53,6 +53,7 @@ static int utimes_common(struct path *path, struct timespec *times)
int error;
struct iattr newattrs;
struct inode *inode = path->dentry->d_inode;
+ struct inode *delegated_inode = NULL;
error = mnt_want_write(path->mnt);
if (error)
@@ -101,9 +102,15 @@ static int utimes_common(struct path *path, struct timespec *times)
goto mnt_drop_write_and_out;
}
}
+retry_deleg:
mutex_lock(&inode->i_mutex);
- error = notify_change(path->dentry, &newattrs);
+ error = notify_change(path->dentry, &newattrs, &delegated_inode);
mutex_unlock(&inode->i_mutex);
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry_deleg;
+ }
mnt_drop_write_and_out:
mnt_drop_write(path->mnt);
View
@@ -2278,7 +2278,7 @@ extern void emergency_remount(void);
#ifdef CONFIG_BLOCK
extern sector_t bmap(struct inode *, sector_t);
#endif
-extern int notify_change(struct dentry *, struct iattr *);
+extern int notify_change(struct dentry *, struct iattr *, struct inode **);
extern int inode_permission(struct inode *, int);
extern int generic_permission(struct inode *, int);

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