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ocfs2: shared writeable mmap

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Implement cluster consistent shared writeable mappings using the
->page_mkwrite() callback.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
This commit is contained in:
Mark Fasheh
2007-05-09 15:16:19 -07:00
parent 607d44aa3f
commit 7307de8051
4 changed files with 200 additions and 39 deletions
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167
fs/ocfs2/mmap.c
View File

@@ -37,11 +37,29 @@
#include "ocfs2.h"
#include "aops.h"
#include "dlmglue.h"
#include "file.h"
#include "inode.h"
#include "mmap.h"
static inline int ocfs2_vm_op_block_sigs(sigset_t *blocked, sigset_t *oldset)
{
/* The best way to deal with signals in the vm path is
* to block them upfront, rather than allowing the
* locking paths to return -ERESTARTSYS. */
sigfillset(blocked);
/* We should technically never get a bad return value
* from sigprocmask */
return sigprocmask(SIG_BLOCK, blocked, oldset);
}
static inline int ocfs2_vm_op_unblock_sigs(sigset_t *oldset)
{
return sigprocmask(SIG_SETMASK, oldset, NULL);
}
static struct page *ocfs2_nopage(struct vm_area_struct * area,
unsigned long address,
int *type)
@@ -53,14 +71,7 @@ static struct page *ocfs2_nopage(struct vm_area_struct * area,
mlog_entry("(area=%p, address=%lu, type=%p)\n", area, address,
type);
/* The best way to deal with signals in this path is
* to block them upfront, rather than allowing the
* locking paths to return -ERESTARTSYS. */
sigfillset(&blocked);
/* We should technically never get a bad ret return
* from sigprocmask */
ret = sigprocmask(SIG_BLOCK, &blocked, &oldset);
ret = ocfs2_vm_op_block_sigs(&blocked, &oldset);
if (ret < 0) {
mlog_errno(ret);
goto out;
@@ -68,7 +79,7 @@ static struct page *ocfs2_nopage(struct vm_area_struct * area,
page = filemap_nopage(area, address, type);
ret = sigprocmask(SIG_SETMASK, &oldset, NULL);
ret = ocfs2_vm_op_unblock_sigs(&oldset);
if (ret < 0)
mlog_errno(ret);
out:
@@ -76,27 +87,135 @@ out:
return page;
}
static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
struct page *page)
{
int ret;
struct address_space *mapping = inode->i_mapping;
loff_t pos = page->index << PAGE_CACHE_SHIFT;
unsigned int len = PAGE_CACHE_SIZE;
pgoff_t last_index;
struct page *locked_page = NULL;
void *fsdata;
loff_t size = i_size_read(inode);
/*
* Another node might have truncated while we were waiting on
* cluster locks.
*/
last_index = size >> PAGE_CACHE_SHIFT;
if (page->index > last_index) {
ret = -EINVAL;
goto out;
}
/*
* The i_size check above doesn't catch the case where nodes
* truncated and then re-extended the file. We'll re-check the
* page mapping after taking the page lock inside of
* ocfs2_write_begin_nolock().
*/
if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
ret = -EINVAL;
goto out;
}
/*
* Call ocfs2_write_begin() and ocfs2_write_end() to take
* advantage of the allocation code there. We pass a write
* length of the whole page (chopped to i_size) to make sure
* the whole thing is allocated.
*
* Since we know the page is up to date, we don't have to
* worry about ocfs2_write_begin() skipping some buffer reads
* because the "write" would invalidate their data.
*/
if (page->index == last_index)
len = size & ~PAGE_CACHE_MASK;
ret = ocfs2_write_begin_nolock(mapping, pos, len, 0, &locked_page,
&fsdata, di_bh, page);
if (ret) {
if (ret != -ENOSPC)
mlog_errno(ret);
goto out;
}
ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
fsdata);
if (ret < 0) {
mlog_errno(ret);
goto out;
}
BUG_ON(ret != len);
ret = 0;
out:
return ret;
}
static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct page *page)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
struct buffer_head *di_bh = NULL;
sigset_t blocked, oldset;
int ret, ret2;
ret = ocfs2_vm_op_block_sigs(&blocked, &oldset);
if (ret < 0) {
mlog_errno(ret);
return ret;
}
/*
* The cluster locks taken will block a truncate from another
* node. Taking the data lock will also ensure that we don't
* attempt page truncation as part of a downconvert.
*/
ret = ocfs2_meta_lock(inode, &di_bh, 1);
if (ret < 0) {
mlog_errno(ret);
goto out;
}
/*
* The alloc sem should be enough to serialize with
* ocfs2_truncate_file() changing i_size as well as any thread
* modifying the inode btree.
*/
down_write(&OCFS2_I(inode)->ip_alloc_sem);
ret = ocfs2_data_lock(inode, 1);
if (ret < 0) {
mlog_errno(ret);
goto out_meta_unlock;
}
ret = __ocfs2_page_mkwrite(inode, di_bh, page);
ocfs2_data_unlock(inode, 1);
out_meta_unlock:
up_write(&OCFS2_I(inode)->ip_alloc_sem);
brelse(di_bh);
ocfs2_meta_unlock(inode, 1);
out:
ret2 = ocfs2_vm_op_unblock_sigs(&oldset);
if (ret2 < 0)
mlog_errno(ret2);
return ret;
}
static struct vm_operations_struct ocfs2_file_vm_ops = {
.nopage = ocfs2_nopage,
.nopage = ocfs2_nopage,
.page_mkwrite = ocfs2_page_mkwrite,
};
int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret = 0, lock_level = 0;
struct ocfs2_super *osb = OCFS2_SB(file->f_dentry->d_inode->i_sb);
/*
* Only support shared writeable mmap for local mounts which
* don't know about holes.
*/
if ((!ocfs2_mount_local(osb) || ocfs2_sparse_alloc(osb)) &&
((vma->vm_flags & VM_SHARED) || (vma->vm_flags & VM_MAYSHARE)) &&
((vma->vm_flags & VM_WRITE) || (vma->vm_flags & VM_MAYWRITE))) {
mlog(0, "disallow shared writable mmaps %lx\n", vma->vm_flags);
/* This is -EINVAL because generic_file_readonly_mmap
* returns it in a similar situation. */
return -EINVAL;
}
ret = ocfs2_meta_lock_atime(file->f_dentry->d_inode,
file->f_vfsmnt, &lock_level);