On Wed, 17 Jul 2013 16:50:13 -0400
"J. Bruce Fields" <bfields@xxxxxxxxxx> wrote:
> From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
>
> NFSv4 uses leases to guarantee that clients can cache metadata as well
> as data.
>
> Cc: Mikulas Patocka <mikulas@xxxxxxxxxxxxxxxxxxxxxxxx>
> Cc: David Howells <dhowells@xxxxxxxxxx>
> Cc: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>
> Cc: Dustin Kirkland <dustin.kirkland@xxxxxxxxxxx>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
> ---
> drivers/base/devtmpfs.c | 4 ++--
> fs/attr.c | 25 ++++++++++++++++++++++++-
> fs/cachefiles/interface.c | 4 ++--
> fs/ecryptfs/inode.c | 2 +-
> fs/hpfs/namei.c | 2 +-
> fs/inode.c | 6 +++++-
> fs/nfsd/vfs.c | 8 ++++++--
> fs/open.c | 22 ++++++++++++++++++----
> fs/utimes.c | 9 ++++++++-
> include/linux/fs.h | 2 +-
> 10 files changed, 68 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
> index 1b8490e..0f38201 100644
> --- a/drivers/base/devtmpfs.c
> +++ b/drivers/base/devtmpfs.c
> @@ -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)
> diff --git a/fs/attr.c b/fs/attr.c
> index 1449adb..267968d 100644
> --- a/fs/attr.c
> +++ b/fs/attr.c
> @@ -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);
> diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
> index d4c1206..ccc01f1 100644
> --- a/fs/cachefiles/interface.c
> +++ b/fs/cachefiles/interface.c
> @@ -424,14 +424,14 @@ 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);
> diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
> index cb3ac33..7b19ebb 100644
> --- a/fs/ecryptfs/inode.c
> +++ b/fs/ecryptfs/inode.c
> @@ -992,7 +992,7 @@ 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);
> diff --git a/fs/hpfs/namei.c b/fs/hpfs/namei.c
> index 345713d..1b39afd 100644
> --- a/fs/hpfs/namei.c
> +++ b/fs/hpfs/namei.c
> @@ -407,7 +407,7 @@ again:
> /*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;
> diff --git a/fs/inode.c b/fs/inode.c
> index 4178e91..82a5a30 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1642,7 +1642,11 @@ 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)
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 5479fff..2586f6d 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -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);
> }
> @@ -987,7 +987,11 @@ 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);
> }
>
> diff --git a/fs/open.c b/fs/open.c
> index 9156cb0..68e50fd 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -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 @@ out:
> 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;
> }
> @@ -523,6 +531,7 @@ 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;
> @@ -547,12 +556,17 @@ 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;
> }
>
> diff --git a/fs/utimes.c b/fs/utimes.c
> index f4fb7ec..aa138d6 100644
> --- a/fs/utimes.c
> +++ b/fs/utimes.c
> @@ -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);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index a2403f9..638cdae 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2268,7 +2268,7 @@ 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);
>
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
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