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From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Jan Kara <jack@suse.cz>, Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-nvdimm@lists.01.org, Jeff Moyer <jmoyer@redhat.com>,
	linux-ext4@vger.kernel.org, Lukas Czerner <lczerner@redhat.com>
Subject: [PATCH v4 2/2] ext4: handle layout changes to pinned DAX mappings
Date: Tue, 10 Jul 2018 13:10:31 -0600	[thread overview]
Message-ID: <20180710191031.17919-3-ross.zwisler@linux.intel.com> (raw)
In-Reply-To: <20180710191031.17919-1-ross.zwisler@linux.intel.com>

Follow the lead of xfs_break_dax_layouts() and add synchronization between
operations in ext4 which remove blocks from an inode (hole punch, truncate
down, etc.) and pages which are pinned due to DAX DMA operations.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
---
 fs/ext4/ext4.h     |  1 +
 fs/ext4/extents.c  | 17 +++++++++++++++++
 fs/ext4/inode.c    | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/ext4/truncate.h |  4 ++++
 4 files changed, 68 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0b127853c584..34bccd64d83d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2460,6 +2460,7 @@ extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *);
 extern int ext4_inode_attach_jinode(struct inode *inode);
 extern int ext4_can_truncate(struct inode *inode);
 extern int ext4_truncate(struct inode *);
+extern int ext4_break_layouts(struct inode *);
 extern int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length);
 extern int ext4_truncate_restart_trans(handle_t *, struct inode *, int nblocks);
 extern void ext4_set_inode_flags(struct inode *);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0057fe3f248d..b8161e6b88d1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4820,6 +4820,13 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 		 * released from page cache.
 		 */
 		down_write(&EXT4_I(inode)->i_mmap_sem);
+
+		ret = ext4_break_layouts(inode);
+		if (ret) {
+			up_write(&EXT4_I(inode)->i_mmap_sem);
+			goto out_mutex;
+		}
+
 		ret = ext4_update_disksize_before_punch(inode, offset, len);
 		if (ret) {
 			up_write(&EXT4_I(inode)->i_mmap_sem);
@@ -5493,6 +5500,11 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
 	 * page cache.
 	 */
 	down_write(&EXT4_I(inode)->i_mmap_sem);
+
+	ret = ext4_break_layouts(inode);
+	if (ret)
+		goto out_mmap;
+
 	/*
 	 * Need to round down offset to be aligned with page size boundary
 	 * for page size > block size.
@@ -5641,6 +5653,11 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
 	 * page cache.
 	 */
 	down_write(&EXT4_I(inode)->i_mmap_sem);
+
+	ret = ext4_break_layouts(inode);
+	if (ret)
+		goto out_mmap;
+
 	/*
 	 * Need to round down to align start offset to page size boundary
 	 * for page size > block size.
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2ea07efbe016..fadb8ecacb1e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4193,6 +4193,39 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
 	return 0;
 }
 
+static void ext4_wait_dax_page(struct ext4_inode_info *ei, bool *did_unlock)
+{
+	*did_unlock = true;
+	up_write(&ei->i_mmap_sem);
+	schedule();
+	down_write(&ei->i_mmap_sem);
+}
+
+int ext4_break_layouts(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct page *page;
+	bool retry;
+	int error;
+
+	if (WARN_ON_ONCE(!rwsem_is_locked(&ei->i_mmap_sem)))
+		return -EINVAL;
+
+	do {
+		retry = false;
+		page = dax_layout_busy_page(inode->i_mapping);
+		if (!page)
+			return 0;
+
+		error = ___wait_var_event(&page->_refcount,
+				atomic_read(&page->_refcount) == 1,
+				TASK_INTERRUPTIBLE, 0, 0,
+				ext4_wait_dax_page(ei, &retry));
+	} while (error == 0 && retry);
+
+	return error;
+}
+
 /*
  * ext4_punch_hole: punches a hole in a file by releasing the blocks
  * associated with the given offset and length
@@ -4266,6 +4299,11 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
 	 * page cache.
 	 */
 	down_write(&EXT4_I(inode)->i_mmap_sem);
+
+	ret = ext4_break_layouts(inode);
+	if (ret)
+		goto out_dio;
+
 	first_block_offset = round_up(offset, sb->s_blocksize);
 	last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
 
@@ -5554,6 +5592,14 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 				ext4_wait_for_tail_page_commit(inode);
 		}
 		down_write(&EXT4_I(inode)->i_mmap_sem);
+
+		rc = ext4_break_layouts(inode);
+		if (rc) {
+			up_write(&EXT4_I(inode)->i_mmap_sem);
+			error = rc;
+			goto err_out;
+		}
+
 		/*
 		 * Truncate pagecache after we've waited for commit
 		 * in data=journal mode to make pages freeable.
diff --git a/fs/ext4/truncate.h b/fs/ext4/truncate.h
index 0cb13badf473..bcbe3668c1d4 100644
--- a/fs/ext4/truncate.h
+++ b/fs/ext4/truncate.h
@@ -11,6 +11,10 @@
  */
 static inline void ext4_truncate_failed_write(struct inode *inode)
 {
+	/*
+	 * We don't need to call ext4_break_layouts() because the blocks we
+	 * are truncating were never visible to userspace.
+	 */
 	down_write(&EXT4_I(inode)->i_mmap_sem);
 	truncate_inode_pages(inode->i_mapping, inode->i_size);
 	ext4_truncate(inode);
-- 
2.14.4

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  parent reply	other threads:[~2018-07-10 19:10 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10 19:10 [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch Ross Zwisler
2018-07-10 19:10 ` [PATCH v4 1/2] dax: dax_layout_busy_page() warn on !exceptional Ross Zwisler
2018-08-10 19:52   ` Eric Sandeen
2018-08-10 20:33     ` Theodore Y. Ts'o
2018-08-11  2:10       ` Theodore Y. Ts'o
2018-08-13 10:12         ` Jan Kara
2018-08-13 12:46           ` Theodore Y. Ts'o
2018-08-24 15:44           ` Jan Kara
2018-08-27 16:09           ` Jan Kara
2018-07-10 19:10 ` Ross Zwisler [this message]
2018-07-11  8:17 ` [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch Jan Kara
2018-07-11 15:41   ` Ross Zwisler
2018-07-25 22:28   ` Ross Zwisler
2018-07-27 16:28     ` Ross Zwisler
2018-08-06  3:55       ` Dave Chinner
2018-08-06 15:49         ` Christoph Hellwig
2018-08-06 22:25           ` Dave Chinner
2018-08-07  8:45       ` Jan Kara
2018-09-10 22:18         ` Eric Sandeen
2018-09-11 15:14           ` Jan Kara
2018-09-11 15:20             ` Jan Kara
2018-09-11 17:28               ` Theodore Y. Ts'o
2018-09-11 18:21                 ` Eric Sandeen
2018-07-31 19:44 ` Ross Zwisler

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