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don't bother with {get,put}_write_access() on non-regular files

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it's pointless and actually leads to wrong behaviour in at least one
moderately convoluted case (pipe(), close one end, try to get to
another via /proc/*/fd and run into ETXTBUSY).

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-03-14 10:56:20 -04:00
parent 44ba8406d0
commit dd20908a8a
2 changed files with 9 additions and 21 deletions
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4
fs/file_table.c
View File

@ -209,10 +209,10 @@ static 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);
if (special_file(inode->i_mode))
return;
put_write_access(inode);
if (file_check_writeable(file) != 0)
return;
__mnt_drop_write(mnt);

26
fs/open.c
View File

@ -641,23 +641,12 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
static inline int __get_file_write_access(struct inode *inode,
struct vfsmount *mnt)
{
int error;
error = get_write_access(inode);
int error = get_write_access(inode);
if (error)
return error;
/*
* Do not take mount writer counts on
* special files since no writes to
* the mount itself will occur.
*/
if (!special_file(inode->i_mode)) {
/*
* Balanced in __fput()
*/
error = __mnt_want_write(mnt);
if (error)
put_write_access(inode);
}
error = __mnt_want_write(mnt);
if (error)
put_write_access(inode);
return error;
}
@ -690,12 +679,11 @@ static int do_dentry_open(struct file *f,
path_get(&f->f_path);
inode = f->f_inode = f->f_path.dentry->d_inode;
if (f->f_mode & FMODE_WRITE) {
if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
error = __get_file_write_access(inode, f->f_path.mnt);
if (error)
goto cleanup_file;
if (!special_file(inode->i_mode))
file_take_write(f);
file_take_write(f);
}
f->f_mapping = inode->i_mapping;
@ -742,7 +730,6 @@ static int do_dentry_open(struct file *f,
cleanup_all:
fops_put(f->f_op);
if (f->f_mode & FMODE_WRITE) {
put_write_access(inode);
if (!special_file(inode->i_mode)) {
/*
* We don't consider this a real
@ -750,6 +737,7 @@ static int do_dentry_open(struct file *f,
* because it all happenend right
* here, so just reset the state.
*/
put_write_access(inode);
file_reset_write(f);
__mnt_drop_write(f->f_path.mnt);
}