In preparation for implementing the direct IO write code path modifications
that make us of iomap infrastructure we need to move out the inode
extension/truncate code from ext4_iomap_end() callback. For direct IO, if the
current code remained it would behave incorrectly. If we update the inode size
prior to converting unwritten extents we run the risk of allowing a racing
direct IO read operation to find unwritten extents before they are converted.
The inode extension/truncate has been moved out into a new function
ext4_handle_inode_extension(). This will be used by both direct IO and DAX
code paths if the write results with the inode being extended.
Signed-off-by: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx>
---
fs/ext4/file.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
fs/ext4/inode.c | 48 +--------------------------------------------
2 files changed, 60 insertions(+), 48 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 360eff7b6aa2..7470800c63b7 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -33,6 +33,7 @@
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"
+#include "truncate.h"
static bool ext4_dio_checks(struct inode *inode)
{
@@ -234,12 +235,62 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
return iov_iter_count(from);
}
+static int ext4_handle_inode_extension(struct inode *inode, loff_t size,
+ size_t count)
+{
+ handle_t *handle;
+ bool truncate = false;
+ ext4_lblk_t written_blk, end_blk;
+ int ret = 0, blkbits = inode->i_blkbits;
+
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto orphan_del;
+ }
+
+ if (ext4_update_inode_size(inode, size))
+ ext4_mark_inode_dirty(handle, inode);
+
+ /*
+ * We may need truncate allocated but not written blocks
+ * beyond EOF.
+ */
+ written_blk = ALIGN(size, 1 << blkbits);
+ end_blk = ALIGN(size + count, 1 << blkbits);
+ if (written_blk < end_blk && ext4_can_truncate(inode))
+ truncate = true;
+
+ /*
+ * Remove the inode from the orphan list if it has been
+ * extended and everything went OK.
+ */
+ if (!truncate && inode->i_nlink)
+ ext4_orphan_del(handle, inode);
+ ext4_journal_stop(handle);
+
+ if (truncate) {
+ ext4_truncate_failed_write(inode);
+orphan_del:
+ /*
+ * If the truncate operation failed early the inode
+ * may still be on the orphan list. In that case, we
+ * need try remove the inode from the linked list in
+ * memory.
+ */
+ if (inode->i_nlink)
+ ext4_orphan_del(NULL, inode);
+ }
+ return ret;
+}
+
#ifdef CONFIG_FS_DAX
static ssize_t
ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
- struct inode *inode = file_inode(iocb->ki_filp);
+ int err;
ssize_t ret;
+ struct inode *inode = file_inode(iocb->ki_filp);
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
@@ -257,6 +308,13 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
goto out;
ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
+
+ if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
+ err = ext4_handle_inode_extension(inode, iocb->ki_pos,
+ iov_iter_count(from));
+ if (err)
+ ret = err;
+ }
out:
inode_unlock(inode);
if (ret > 0)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 420fe3deed39..761ce6286b05 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3601,53 +3601,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
ssize_t written, unsigned flags, struct iomap *iomap)
{
- int ret = 0;
- handle_t *handle;
- int blkbits = inode->i_blkbits;
- bool truncate = false;
-
- if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
- return 0;
-
- handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- goto orphan_del;
- }
- if (ext4_update_inode_size(inode, offset + written))
- ext4_mark_inode_dirty(handle, inode);
- /*
- * We may need to truncate allocated but not written blocks beyond EOF.
- */
- if (iomap->offset + iomap->length >
- ALIGN(inode->i_size, 1 << blkbits)) {
- ext4_lblk_t written_blk, end_blk;
-
- written_blk = (offset + written) >> blkbits;
- end_blk = (offset + length) >> blkbits;
- if (written_blk < end_blk && ext4_can_truncate(inode))
- truncate = true;
- }
- /*
- * Remove inode from orphan list if we were extending a inode and
- * everything went fine.
- */
- if (!truncate && inode->i_nlink &&
- !list_empty(&EXT4_I(inode)->i_orphan))
- ext4_orphan_del(handle, inode);
- ext4_journal_stop(handle);
- if (truncate) {
- ext4_truncate_failed_write(inode);
-orphan_del:
- /*
- * If truncate failed early the inode might still be on the
- * orphan list; we need to make sure the inode is removed from
- * the orphan list in that case.
- */
- if (inode->i_nlink)
- ext4_orphan_del(NULL, inode);
- }
- return ret;
+ return 0;
}
const struct iomap_ops ext4_iomap_ops = {
--
2.16.4
--
Matthew Bobrowski
