| From dd20908a8a06b22c171f6c3fcdbdbd65bed07505 Mon Sep 17 00:00:00 2001 |
| From: Al Viro <viro@zeniv.linux.org.uk> |
| Date: Fri, 14 Mar 2014 10:56:20 -0400 |
| Subject: don't bother with {get,put}_write_access() on non-regular files |
| |
| From: Al Viro <viro@zeniv.linux.org.uk> |
| |
| commit dd20908a8a06b22c171f6c3fcdbdbd65bed07505 upstream. |
| |
| 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). |
| |
| Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/file_table.c | 4 ++-- |
| fs/open.c | 26 +++++++------------------- |
| 2 files changed, 9 insertions(+), 21 deletions(-) |
| |
| --- a/fs/file_table.c |
| +++ b/fs/file_table.c |
| @@ -209,10 +209,10 @@ static void drop_file_write_access(struc |
| 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); |
| --- a/fs/open.c |
| +++ b/fs/open.c |
| @@ -641,23 +641,12 @@ out: |
| 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 @@ cleanup_all: |
| * 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); |
| } |