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ocfs2: take data locks around extend

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We need to take a data lock around extends to protect the pages that
ocfs2_zero_extend is going to be pulling into the page cache. Otherwise an
extend on one node might populate the page cache with data pages that have
no lock coverage.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
This commit is contained in:
Mark Fasheh
2006-05-05 19:04:03 -07:00
parent 0c056c50a6
commit 53013cba41
3 changed files with 88 additions and 34 deletions
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46
fs/ocfs2/aops.c
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@@ -276,13 +276,29 @@ static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
return ret;
}
/* This can also be called from ocfs2_write_zero_page() which has done
* it's own cluster locking. */
int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
unsigned from, unsigned to)
{
int ret;
down_read(&OCFS2_I(inode)->ip_alloc_sem);
ret = block_prepare_write(page, from, to, ocfs2_get_block);
up_read(&OCFS2_I(inode)->ip_alloc_sem);
return ret;
}
/*
* ocfs2_prepare_write() can be an outer-most ocfs2 call when it is called
* from loopback. It must be able to perform its own locking around
* ocfs2_get_block().
*/
int ocfs2_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
static int ocfs2_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
struct inode *inode = page->mapping->host;
int ret;
@@ -295,11 +311,7 @@ int ocfs2_prepare_write(struct file *file, struct page *page,
goto out;
}
down_read(&OCFS2_I(inode)->ip_alloc_sem);
ret = block_prepare_write(page, from, to, ocfs2_get_block);
up_read(&OCFS2_I(inode)->ip_alloc_sem);
ret = ocfs2_prepare_write_nolock(inode, page, from, to);
ocfs2_meta_unlock(inode, 0);
out:
@@ -625,11 +637,31 @@ static ssize_t ocfs2_direct_IO(int rw,
int ret;
mlog_entry_void();
/*
* We get PR data locks even for O_DIRECT. This allows
* concurrent O_DIRECT I/O but doesn't let O_DIRECT with
* extending and buffered zeroing writes race. If they did
* race then the buffered zeroing could be written back after
* the O_DIRECT I/O. It's one thing to tell people not to mix
* buffered and O_DIRECT writes, but expecting them to
* understand that file extension is also an implicit buffered
* write is too much. By getting the PR we force writeback of
* the buffered zeroing before proceeding.
*/
ret = ocfs2_data_lock(inode, 0);
if (ret < 0) {
mlog_errno(ret);
goto out;
}
ocfs2_data_unlock(inode, 0);
ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
inode->i_sb->s_bdev, iov, offset,
nr_segs,
ocfs2_direct_IO_get_blocks,
ocfs2_dio_end_io);
out:
mlog_exit(ret);
return ret;
}