From aceaf78da92a53f5e1b105649a1b8c0afdb2135c Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 15 Feb 2008 14:37:31 -0800 Subject: [PATCH] r/o bind mounts: create helper to drop file write access If someone decides to demote a file from r/w to just r/o, they can use this same code as __fput(). NFS does just that, and will use this in the next patch. AV: drop write access in __fput() only after we evict from file list. Signed-off-by: Dave Hansen Cc: Erez Zadok Cc: Trond Myklebust Cc: "J Bruce Fields" Acked-by: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/file_table.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'fs/file_table.c') diff --git a/fs/file_table.c b/fs/file_table.c index 986ff4ed0a7c..3f73eb1f195a 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -211,6 +211,23 @@ void fput(struct file *file) EXPORT_SYMBOL(fput); +/** + * drop_file_write_access - give up ability to write to a file + * @file: the file to which we will stop writing + * + * This is a central place which will give up the ability + * to write to @file, along with access to write through + * its vfsmount. + */ +void drop_file_write_access(struct file *file) +{ + struct dentry *dentry = file->f_path.dentry; + struct inode *inode = dentry->d_inode; + + put_write_access(inode); +} +EXPORT_SYMBOL_GPL(drop_file_write_access); + /* __fput is called from task context when aio completion releases the last * last use of a struct file *. Do not use otherwise. */ @@ -236,10 +253,10 @@ void __fput(struct file *file) if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL)) cdev_put(inode->i_cdev); fops_put(file->f_op); - if (file->f_mode & FMODE_WRITE) - put_write_access(inode); put_pid(file->f_owner.pid); file_kill(file); + if (file->f_mode & FMODE_WRITE) + drop_file_write_access(file); file->f_path.dentry = NULL; file->f_path.mnt = NULL; file_free(file); -- cgit v1.2.3