ocfs2: shared writeable mmap
Implement cluster consistent shared writeable mappings using the
->page_mkwrite() callback.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index fc723fb..b8869fd 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1034,7 +1034,8 @@
*/
static int ocfs2_grab_pages_for_write(struct address_space *mapping,
struct ocfs2_write_ctxt *wc,
- u32 cpos, loff_t user_pos, int new)
+ u32 cpos, loff_t user_pos, int new,
+ struct page *mmap_page)
{
int ret = 0, i;
unsigned long start, target_index, index;
@@ -1058,11 +1059,36 @@
for(i = 0; i < wc->w_num_pages; i++) {
index = start + i;
- wc->w_pages[i] = find_or_create_page(mapping, index, GFP_NOFS);
- if (!wc->w_pages[i]) {
- ret = -ENOMEM;
- mlog_errno(ret);
- goto out;
+ if (index == target_index && mmap_page) {
+ /*
+ * ocfs2_pagemkwrite() is a little different
+ * and wants us to directly use the page
+ * passed in.
+ */
+ lock_page(mmap_page);
+
+ if (mmap_page->mapping != mapping) {
+ unlock_page(mmap_page);
+ /*
+ * Sanity check - the locking in
+ * ocfs2_pagemkwrite() should ensure
+ * that this code doesn't trigger.
+ */
+ ret = -EINVAL;
+ mlog_errno(ret);
+ goto out;
+ }
+
+ page_cache_get(mmap_page);
+ wc->w_pages[i] = mmap_page;
+ } else {
+ wc->w_pages[i] = find_or_create_page(mapping, index,
+ GFP_NOFS);
+ if (!wc->w_pages[i]) {
+ ret = -ENOMEM;
+ mlog_errno(ret);
+ goto out;
+ }
}
if (index == target_index)
@@ -1213,10 +1239,10 @@
}
}
-static int ocfs2_write_begin_nolock(struct address_space *mapping,
- loff_t pos, unsigned len, unsigned flags,
- struct page **pagep, void **fsdata,
- struct buffer_head *di_bh)
+int ocfs2_write_begin_nolock(struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
+ struct buffer_head *di_bh, struct page *mmap_page)
{
int ret, i, credits = OCFS2_INODE_UPDATE_CREDITS;
unsigned int num_clusters = 0, clusters_to_alloc = 0;
@@ -1318,7 +1344,7 @@
* extent.
*/
ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
- clusters_to_alloc);
+ clusters_to_alloc, mmap_page);
if (ret) {
mlog_errno(ret);
goto out_commit;
@@ -1386,7 +1412,7 @@
}
ret = ocfs2_write_begin_nolock(mapping, pos, len, flags, pagep,
- fsdata, di_bh);
+ fsdata, di_bh, NULL);
if (ret) {
mlog_errno(ret);
goto out_fail_data;
@@ -1407,9 +1433,9 @@
return ret;
}
-static int ocfs2_write_end_nolock(struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
+int ocfs2_write_end_nolock(struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
{
int i;
unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
diff --git a/fs/ocfs2/aops.h b/fs/ocfs2/aops.h
index bdcdd1a..389579b 100644
--- a/fs/ocfs2/aops.h
+++ b/fs/ocfs2/aops.h
@@ -50,6 +50,15 @@
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata);
+int ocfs2_write_end_nolock(struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata);
+
+int ocfs2_write_begin_nolock(struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
+ struct buffer_head *di_bh, struct page *mmap_page);
+
/* all ocfs2_dio_end_io()'s fault */
#define ocfs2_iocb_is_rw_locked(iocb) \
test_bit(0, (unsigned long *)&iocb->private)
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 4c850d0..a80f317 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1001,6 +1001,13 @@
goto bail_unlock;
}
+ /*
+ * This will intentionally not wind up calling vmtruncate(),
+ * since all the work for a size change has been done above.
+ * Otherwise, we could get into problems with truncate as
+ * ip_alloc_sem is used there to protect against i_size
+ * changes.
+ */
status = inode_setattr(inode, attr);
if (status < 0) {
mlog_errno(status);
diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
index af01158..d79aa12 100644
--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -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 @@
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 @@
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 @@
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);