From: Pekka Enberg <[email protected]>
As pointed out by Andrew Morton, if some process is partway through a
big page_cache_readahead() operation, a concurrent
invalidate_inode_pages2() is not enough to revoke inode pages. This
patch changes the revoke code to modify ->f_mapping to point to a
revoked mapping that will cause any future operations on the mapping
to fail with EIO.
Signed-off-by: Pekka Enberg <[email protected]>
---
fs/revoke.c | 29 ++++++++++++++++++++---------
fs/revoked_inode.c | 39 +++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 4 ++--
include/linux/mm.h | 1 +
mm/mmap.c | 11 +++++++++++
5 files changed, 73 insertions(+), 11 deletions(-)
Index: uml-2.6/fs/revoke.c
===================================================================
--- uml-2.6.orig/fs/revoke.c 2007-04-12 18:17:55.000000000 +0300
+++ uml-2.6/fs/revoke.c 2007-04-19 16:55:14.000000000 +0300
@@ -201,6 +201,10 @@ if (ret < 0) {
err = ret;
break;
}
+
+ unlink_file_vma(vma);
+ fput(vma->vm_file);
+ vma->vm_file = NULL;
}
up_read(&mm->mmap_sem);
return err;
@@ -290,6 +294,10 @@ int err = 0;
err = revoke_vma(vma, &details);
if (err)
break;
+
+ __unlink_file_vma(vma);
+ fput(vma->vm_file);
+ vma->vm_file = NULL;
}
up_write(&mm->mmap_sem);
out:
@@ -317,12 +325,10 @@ vma_prio_tree_foreach(vma, &iter, &mapp
continue;
err = revoke_mm(vma->vm_mm, mapping, to_exclude);
- if (err == -EAGAIN) {
+ if (err == -EAGAIN)
try_again = 1;
- continue;
- }
- if (err == -EINTR)
- goto restart;
+
+ goto restart;
}
if (try_again) {
cond_resched();
@@ -418,9 +424,11 @@ int err = 0;
for (i = 0; i < table->end; i++) {
struct revokefs_inode_info *info;
struct file *this, *filp;
+ struct inode *inode;
this = table->files[i];
- info = revokefs_i(this->f_dentry->d_inode);
+ inode = this->f_dentry->d_inode;
+ info = revokefs_i(inode);
/*
* Increase count before attempting to close file as
@@ -428,7 +436,7 @@ for (i = 0; i < table->end; i++) {
*/
table->restore_start++;
filp = info->file;
- err = filp->f_op->revoke(filp);
+ err = filp->f_op->revoke(filp, inode->i_mapping);
put_task_struct(info->owner);
info->owner = NULL; /* To avoid restoring closed file. */
if (err)
@@ -633,8 +641,9 @@ asmlinkage long sys_frevoke(unsigned int
return err;
}
-int generic_file_revoke(struct file *file)
+int generic_file_revoke(struct file *file, struct address_space *new_mapping)
{
+ struct address_space *mapping = file->f_mapping;
int err;
/*
@@ -644,10 +653,12 @@ int generic_file_revoke(struct file *fil
if (err)
goto out;
+ file->f_mapping = new_mapping;
+
/*
* Make pending reads fail.
*/
- err = invalidate_inode_pages2(file->f_mapping);
+ err = invalidate_inode_pages2(mapping);
out:
return err;
Index: uml-2.6/fs/revoked_inode.c
===================================================================
--- uml-2.6.orig/fs/revoked_inode.c 2007-04-12 18:17:55.000000000 +0300
+++ uml-2.6/fs/revoked_inode.c 2007-04-12 18:29:30.000000000 +0300
@@ -362,6 +362,43 @@ static struct inode_operations revoked_i
/* truncate_range returns void */
};
+static int revoked_readpage(struct file *file, struct page *page)
+{
+ return -EIO;
+}
+
+static int revoked_writepage(struct page *page, struct writeback_control *wbc)
+{
+ return -EIO;
+}
+
+static int revoked_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ return -EIO;
+}
+
+static int revoked_commit_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ return -EIO;
+}
+
+static ssize_t revoked_direct_IO(int rw, struct kiocb *iocb,
+ const struct iovec *iov, loff_t offset,
+ unsigned long nr_segs)
+{
+ return -EIO;
+}
+
+static const struct address_space_operations revoked_aops = {
+ .readpage = revoked_readpage,
+ .writepage = revoked_writepage,
+ .prepare_write = revoked_prepare_write,
+ .commit_write = revoked_commit_write,
+ .direct_IO = revoked_direct_IO,
+};
+
void make_revoked_inode(struct inode *inode, int mode)
{
remove_inode_hash(inode);
@@ -375,4 +412,6 @@ void make_revoked_inode(struct inode *in
inode->i_fop = &revoked_special_file_ops;
else
inode->i_fop = &revoked_file_ops;
+
+ inode->i_mapping->a_ops = &revoked_aops;
}
Index: uml-2.6/include/linux/fs.h
===================================================================
--- uml-2.6.orig/include/linux/fs.h 2007-04-12 18:17:55.000000000 +0300
+++ uml-2.6/include/linux/fs.h 2007-04-12 18:29:30.000000000 +0300
@@ -1100,7 +1100,7 @@ struct file_operations {
int (*flock) (struct file *, int, struct file_lock *);
ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
- int (*revoke)(struct file *);
+ int (*revoke)(struct file *, struct address_space *);
};
struct inode_operations {
@@ -1742,7 +1742,7 @@ extern long do_splice_direct(struct file
/* fs/revoke.c */
#ifdef CONFIG_MMU
-extern int generic_file_revoke(struct file *);
+extern int generic_file_revoke(struct file *, struct address_space *);
#else
#define generic_file_revoke NULL
#endif
Index: uml-2.6/include/linux/mm.h
===================================================================
--- uml-2.6.orig/include/linux/mm.h 2007-04-12 16:57:33.000000000 +0300
+++ uml-2.6/include/linux/mm.h 2007-04-12 19:07:34.000000000 +0300
@@ -1022,6 +1022,7 @@ extern int split_vma(struct mm_struct *,
extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *,
struct rb_node **, struct rb_node *);
+extern void __unlink_file_vma(struct vm_area_struct *);
extern void unlink_file_vma(struct vm_area_struct *);
extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
unsigned long addr, unsigned long len, pgoff_t pgoff);
Index: uml-2.6/mm/mmap.c
===================================================================
--- uml-2.6.orig/mm/mmap.c 2007-04-12 16:57:33.000000000 +0300
+++ uml-2.6/mm/mmap.c 2007-04-19 16:55:47.000000000 +0300
@@ -201,6 +201,17 @@ static void __remove_shared_vm_struct(st
}
/*
+ * Requires inode->i_mapping->i_mmap_lock
+ */
+void __unlink_file_vma(struct vm_area_struct *vma)
+{
+ struct file *file = vma->vm_file;
+ struct address_space *mapping = file->f_mapping;
+
+ __remove_shared_vm_struct(vma, file, mapping);
+}
+
+/*
* Unlink a file-based vm structure from its prio_tree, to hide
* vma from rmap and vmtruncate before freeing its page tables.
*/
-
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