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Message-Id: <1212685513-32237-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Date: Thu, 5 Jun 2008 22:35:13 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: cmm@...ibm.com, akpm@...ux-foundation.org, jack@...e.cz
Cc: linux-ext4@...r.kernel.org,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH] ext3: Use page_mkwrite vma_operations to get mmap write notification.
We would like to get notified when we are doing a write on mmap section.
The changes are needed to handle ENOSPC when writing to an mmap section
of files with holes.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
fs/ext3/file.c | 19 +++++++++++-
fs/ext3/inode.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/ext3_fs.h | 1 +
3 files changed, 95 insertions(+), 1 deletions(-)
diff --git a/fs/ext3/file.c b/fs/ext3/file.c
index acc4913..09e22e4 100644
--- a/fs/ext3/file.c
+++ b/fs/ext3/file.c
@@ -106,6 +106,23 @@ ext3_file_write(struct kiocb *iocb, const struct iovec *iov,
return ret;
}
+static struct vm_operations_struct ext3_file_vm_ops = {
+ .fault = filemap_fault,
+ .page_mkwrite = ext3_page_mkwrite,
+};
+
+static int ext3_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct address_space *mapping = file->f_mapping;
+
+ if (!mapping->a_ops->readpage)
+ return -ENOEXEC;
+ file_accessed(file);
+ vma->vm_ops = &ext3_file_vm_ops;
+ vma->vm_flags |= VM_CAN_NONLINEAR;
+ return 0;
+}
+
const struct file_operations ext3_file_operations = {
.llseek = generic_file_llseek,
.read = do_sync_read,
@@ -116,7 +133,7 @@ ext3_file_write(struct kiocb *iocb, const struct iovec *iov,
#ifdef CONFIG_COMPAT
.compat_ioctl = ext3_compat_ioctl,
#endif
- .mmap = generic_file_mmap,
+ .mmap = ext3_file_mmap,
.open = generic_file_open,
.release = ext3_release_file,
.fsync = ext3_sync_file,
diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 6ae4ecf..c8261f0 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -3295,3 +3295,79 @@ int ext3_change_inode_journal_flag(struct inode *inode, int val)
return err;
}
+
+static int ext3_bh_prepare_fill(handle_t *handle, struct buffer_head *bh)
+{
+ if (!buffer_mapped(bh)) {
+ /*
+ * Mark buffer as dirty so that
+ * block_write_full_page() writes it
+ */
+ set_buffer_dirty(bh);
+ }
+ return 0;
+}
+
+static int ext3_bh_unmapped(handle_t *handle, struct buffer_head *bh)
+{
+ return !buffer_mapped(bh);
+}
+
+int ext3_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+{
+ loff_t size;
+ unsigned long len;
+ int ret = -EINVAL;
+ struct file *file = vma->vm_file;
+ struct inode *inode = file->f_path.dentry->d_inode;
+ struct address_space *mapping = inode->i_mapping;
+ struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = 1 };
+
+ /*
+ * Get i_alloc_sem to stop truncates messing with the inode. We cannot
+ * get i_mutex because we are already holding mmap_sem.
+ */
+ down_read(&inode->i_alloc_sem);
+ size = i_size_read(inode);
+ if (page->mapping != mapping || size <= page_offset(page)
+ || !PageUptodate(page)) {
+ /* page got truncated from under us? */
+ goto out_unlock;
+ }
+ ret = 0;
+ if (PageMappedToDisk(page))
+ goto out_unlock;
+
+ if (page->index == size >> PAGE_CACHE_SHIFT)
+ len = size & ~PAGE_CACHE_MASK;
+ else
+ len = PAGE_CACHE_SIZE;
+
+ if (page_has_buffers(page)) {
+ /* return if we have all the buffers mapped */
+ if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
+ ext3_bh_unmapped))
+ goto out_unlock;
+ /*
+ * Now mark all the buffer head dirty so
+ * that writepage can write it
+ */
+ walk_page_buffers(NULL, page_buffers(page), 0, len,
+ NULL, ext3_bh_prepare_fill);
+ }
+ /*
+ * OK, we need to fill the hole... Lock the page and do writepage.
+ * We can't do write_begin and write_end here because we don't
+ * have inode_mutex and that allow parallel write_begin, write_end call.
+ * (lock_page prevent this from happening on the same page though)
+ */
+ lock_page(page);
+ wbc.range_start = page_offset(page);
+ wbc.range_end = page_offset(page) + len;
+ ret = mapping->a_ops->writepage(page, &wbc);
+ /* writepage unlocks the page */
+out_unlock:
+ up_read(&inode->i_alloc_sem);
+ return ret;
+}
diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
index 36c5403..715c35e 100644
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -836,6 +836,7 @@ extern void ext3_truncate (struct inode *);
extern void ext3_set_inode_flags(struct inode *);
extern void ext3_get_inode_flags(struct ext3_inode_info *);
extern void ext3_set_aops(struct inode *inode);
+extern int ext3_page_mkwrite(struct vm_area_struct *vma, struct page *page);
/* ioctl.c */
extern int ext3_ioctl (struct inode *, struct file *, unsigned int,
--
1.5.5.1.357.g1af8b.dirty
--
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