ocfs2: take data locks around extend
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
parent
0c056c50a6
commit
53013cba41
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@ -276,13 +276,29 @@ static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
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return ret;
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}
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/* This can also be called from ocfs2_write_zero_page() which has done
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* it's own cluster locking. */
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int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
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unsigned from, unsigned to)
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{
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int ret;
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down_read(&OCFS2_I(inode)->ip_alloc_sem);
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ret = block_prepare_write(page, from, to, ocfs2_get_block);
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up_read(&OCFS2_I(inode)->ip_alloc_sem);
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return ret;
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}
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/*
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* ocfs2_prepare_write() can be an outer-most ocfs2 call when it is called
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* from loopback. It must be able to perform its own locking around
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* ocfs2_get_block().
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*/
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int ocfs2_prepare_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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static int ocfs2_prepare_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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{
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struct inode *inode = page->mapping->host;
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int ret;
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@ -295,11 +311,7 @@ int ocfs2_prepare_write(struct file *file, struct page *page,
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goto out;
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}
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down_read(&OCFS2_I(inode)->ip_alloc_sem);
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ret = block_prepare_write(page, from, to, ocfs2_get_block);
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up_read(&OCFS2_I(inode)->ip_alloc_sem);
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ret = ocfs2_prepare_write_nolock(inode, page, from, to);
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ocfs2_meta_unlock(inode, 0);
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out:
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@ -625,11 +637,31 @@ static ssize_t ocfs2_direct_IO(int rw,
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int ret;
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mlog_entry_void();
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/*
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* We get PR data locks even for O_DIRECT. This allows
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* concurrent O_DIRECT I/O but doesn't let O_DIRECT with
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* extending and buffered zeroing writes race. If they did
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* race then the buffered zeroing could be written back after
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* the O_DIRECT I/O. It's one thing to tell people not to mix
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* buffered and O_DIRECT writes, but expecting them to
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* understand that file extension is also an implicit buffered
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* write is too much. By getting the PR we force writeback of
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* the buffered zeroing before proceeding.
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*/
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ret = ocfs2_data_lock(inode, 0);
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if (ret < 0) {
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mlog_errno(ret);
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goto out;
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}
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ocfs2_data_unlock(inode, 0);
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ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
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inode->i_sb->s_bdev, iov, offset,
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nr_segs,
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ocfs2_direct_IO_get_blocks,
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ocfs2_dio_end_io);
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out:
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mlog_exit(ret);
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return ret;
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}
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@ -22,8 +22,8 @@
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#ifndef OCFS2_AOPS_H
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#define OCFS2_AOPS_H
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int ocfs2_prepare_write(struct file *file, struct page *page,
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unsigned from, unsigned to);
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int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
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unsigned from, unsigned to);
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struct ocfs2_journal_handle *ocfs2_start_walk_page_trans(struct inode *inode,
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struct page *page,
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@ -613,7 +613,8 @@ leave:
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/* Some parts of this taken from generic_cont_expand, which turned out
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* to be too fragile to do exactly what we need without us having to
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* worry about recursive locking in ->commit_write(). */
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* worry about recursive locking in ->prepare_write() and
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* ->commit_write(). */
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static int ocfs2_write_zero_page(struct inode *inode,
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u64 size)
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{
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@ -641,7 +642,7 @@ static int ocfs2_write_zero_page(struct inode *inode,
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goto out;
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}
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ret = ocfs2_prepare_write(NULL, page, offset, offset);
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ret = ocfs2_prepare_write_nolock(inode, page, offset, offset);
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if (ret < 0) {
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mlog_errno(ret);
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goto out_unlock;
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@ -695,13 +696,26 @@ out:
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return ret;
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}
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/*
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* A tail_to_skip value > 0 indicates that we're being called from
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* ocfs2_file_aio_write(). This has the following implications:
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*
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* - we don't want to update i_size
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* - di_bh will be NULL, which is fine because it's only used in the
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* case where we want to update i_size.
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* - ocfs2_zero_extend() will then only be filling the hole created
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* between i_size and the start of the write.
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*/
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static int ocfs2_extend_file(struct inode *inode,
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struct buffer_head *di_bh,
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u64 new_i_size)
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u64 new_i_size,
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size_t tail_to_skip)
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{
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int ret = 0;
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u32 clusters_to_add;
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BUG_ON(!tail_to_skip && !di_bh);
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/* setattr sometimes calls us like this. */
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if (new_i_size == 0)
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goto out;
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@ -714,27 +728,44 @@ static int ocfs2_extend_file(struct inode *inode,
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OCFS2_I(inode)->ip_clusters;
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if (clusters_to_add) {
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/*
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* protect the pages that ocfs2_zero_extend is going to
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* be pulling into the page cache.. we do this before the
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* metadata extend so that we don't get into the situation
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* where we've extended the metadata but can't get the data
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* lock to zero.
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*/
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ret = ocfs2_data_lock(inode, 1);
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if (ret < 0) {
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mlog_errno(ret);
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goto out;
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}
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ret = ocfs2_extend_allocation(inode, clusters_to_add);
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if (ret < 0) {
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mlog_errno(ret);
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goto out;
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goto out_unlock;
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}
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ret = ocfs2_zero_extend(inode, new_i_size);
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ret = ocfs2_zero_extend(inode, (u64)new_i_size - tail_to_skip);
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if (ret < 0) {
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mlog_errno(ret);
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goto out;
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goto out_unlock;
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}
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}
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/* No allocation required, we just use this helper to
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* do a trivial update of i_size. */
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ret = ocfs2_simple_size_update(inode, di_bh, new_i_size);
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if (ret < 0) {
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mlog_errno(ret);
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goto out;
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}
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if (!tail_to_skip) {
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/* We're being called from ocfs2_setattr() which wants
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* us to update i_size */
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ret = ocfs2_simple_size_update(inode, di_bh, new_i_size);
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if (ret < 0)
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mlog_errno(ret);
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}
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out_unlock:
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if (clusters_to_add) /* this is the only case in which we lock */
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ocfs2_data_unlock(inode, 1);
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out:
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return ret;
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}
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@ -793,7 +824,7 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
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if (i_size_read(inode) > attr->ia_size)
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status = ocfs2_truncate_file(inode, bh, attr->ia_size);
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else
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status = ocfs2_extend_file(inode, bh, attr->ia_size);
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status = ocfs2_extend_file(inode, bh, attr->ia_size, 0);
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if (status < 0) {
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if (status != -ENOSPC)
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mlog_errno(status);
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@ -1049,21 +1080,12 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
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if (!clusters)
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break;
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ret = ocfs2_extend_allocation(inode, clusters);
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ret = ocfs2_extend_file(inode, NULL, newsize, count);
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if (ret < 0) {
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if (ret != -ENOSPC)
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mlog_errno(ret);
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goto out;
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}
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/* Fill any holes which would've been created by this
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* write. If we're O_APPEND, this will wind up
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* (correctly) being a noop. */
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ret = ocfs2_zero_extend(inode, (u64) newsize - count);
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if (ret < 0) {
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mlog_errno(ret);
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goto out;
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}
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break;
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}
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