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Subject[PATCH 08/17] VFS: Make more complete truncate operation available to CacheFiles
Date
Make a more complete truncate operation available to CacheFiles (including
security checks and suchlike) so that it can use this to clear invalidated
cache files.

Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/open.c | 50 +++++++++++++++++++++++++++-----------------------
include/linux/fs.h | 1 +
2 files changed, 28 insertions(+), 23 deletions(-)
diff --git a/fs/open.c b/fs/open.c
index 77becc0..7535620 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -61,33 +61,22 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
return ret;
}

-static long do_sys_truncate(const char __user *pathname, loff_t length)
+long vfs_truncate(struct path *path, loff_t length)
{
- struct path path;
struct inode *inode;
- int error;
-
- error = -EINVAL;
- if (length < 0) /* sorry, but loff_t says... */
- goto out;
+ long error;

- error = user_path(pathname, &path);
- if (error)
- goto out;
- inode = path.dentry->d_inode;
+ inode = path->dentry->d_inode;

/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
- error = -EISDIR;
if (S_ISDIR(inode->i_mode))
- goto dput_and_out;
-
- error = -EINVAL;
+ return -EISDIR;
if (!S_ISREG(inode->i_mode))
- goto dput_and_out;
+ return -EINVAL;

- error = mnt_want_write(path.mnt);
+ error = mnt_want_write(path->mnt);
if (error)
- goto dput_and_out;
+ goto out;

error = inode_permission(inode, MAY_WRITE);
if (error)
@@ -111,19 +100,34 @@ static long do_sys_truncate(const char __user *pathname, loff_t length)

error = locks_verify_truncate(inode, NULL, length);
if (!error)
- error = security_path_truncate(&path);
+ error = security_path_truncate(path);
if (!error)
- error = do_truncate(path.dentry, length, 0, NULL);
+ error = do_truncate(path->dentry, length, 0, NULL);

put_write_and_out:
put_write_access(inode);
mnt_drop_write_and_out:
- mnt_drop_write(path.mnt);
-dput_and_out:
- path_put(&path);
+ mnt_drop_write(path->mnt);
out:
return error;
}
+EXPORT_SYMBOL_GPL(vfs_truncate);
+
+static long do_sys_truncate(const char __user *pathname, loff_t length)
+{
+ struct path path;
+ int error;
+
+ if (length < 0) /* sorry, but loff_t says... */
+ return -EINVAL;
+
+ error = user_path(pathname, &path);
+ if (!error) {
+ error = vfs_truncate(&path, length);
+ path_put(&path);
+ }
+ return error;
+}

SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 386da09..79449e4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2014,6 +2014,7 @@ static inline int break_lease(struct inode *inode, unsigned int mode)

/* fs/open.c */

+extern long vfs_truncate(struct path *, loff_t);
extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
struct file *filp);
extern int do_fallocate(struct file *file, int mode, loff_t offset,


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