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Date: Tue, 5 Nov 2019 23:01:51 +1100
From: Matthew Bobrowski <mbobrowski@...browski.org>
To: tytso@....edu, jack@...e.cz, adilger.kernel@...ger.ca
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
riteshh@...ux.ibm.com
Subject: [PATCH v7 08/11] ext4: move inode extension/truncate code out from
->iomap_end() callback
In preparation for implementing the iomap direct I/O modifications,
the inode extension/truncate code needs to be moved out from the
ext4_iomap_end() callback. For direct I/O, if the current code
remained, it would behave incorrrectly. Updating the inode size prior
to converting unwritten extents would potentially allow a racing
direct I/O read to find unwritten extents before being converted
correctly.
The inode extension/truncate code now resides within a new helper
ext4_handle_inode_extension(). This function has been designed so that
it can accommodate for both DAX and direct I/O extension/truncate
operations.
Signed-off-by: Matthew Bobrowski <mbobrowski@...browski.org>
Reviewed-by: Jan Kara <jack@...e.cz>
Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>
---
fs/ext4/file.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++-
fs/ext4/inode.c | 48 +-------------------------
2 files changed, 89 insertions(+), 48 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 440f4c6ba4ee..ec54fec96a81 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_supported(struct inode *inode)
{
@@ -234,12 +235,95 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
return iov_iter_count(from);
}
+static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
+ ssize_t written, size_t count)
+{
+ handle_t *handle;
+ bool truncate = false;
+ u8 blkbits = inode->i_blkbits;
+ ext4_lblk_t written_blk, end_blk;
+
+ /*
+ * Note that EXT4_I(inode)->i_disksize can get extended up to
+ * inode->i_size while the I/O was running due to writeback of delalloc
+ * blocks. But, the code in ext4_iomap_alloc() is careful to use
+ * zeroed/unwritten extents if this is possible; thus we won't leave
+ * uninitialized blocks in a file even if we didn't succeed in writing
+ * as much as we intended.
+ */
+ WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
+ if (offset + count <= EXT4_I(inode)->i_disksize) {
+ /*
+ * We need to ensure that the inode is removed from the orphan
+ * list if it has been added prematurely, due to writeback of
+ * delalloc blocks.
+ */
+ if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+
+ if (IS_ERR(handle)) {
+ ext4_orphan_del(NULL, inode);
+ return PTR_ERR(handle);
+ }
+
+ ext4_orphan_del(handle, inode);
+ ext4_journal_stop(handle);
+ }
+
+ return written;
+ }
+
+ if (written < 0)
+ goto truncate;
+
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+ if (IS_ERR(handle)) {
+ written = PTR_ERR(handle);
+ goto truncate;
+ }
+
+ 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.
+ */
+ written_blk = ALIGN(offset + written, 1 << blkbits);
+ end_blk = ALIGN(offset + 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) {
+truncate:
+ ext4_truncate_failed_write(inode);
+ /*
+ * If the truncate operation failed early, then the inode may
+ * still be on the orphan list. In that case, we need to try
+ * remove the inode from the in-memory linked list.
+ */
+ if (inode->i_nlink)
+ ext4_orphan_del(NULL, inode);
+ }
+
+ return written;
+}
+
#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);
ssize_t ret;
+ size_t count;
+ loff_t offset;
+ struct inode *inode = file_inode(iocb->ki_filp);
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
@@ -256,7 +340,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (ret)
goto out;
+ offset = iocb->ki_pos;
+ count = iov_iter_count(from);
ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
+ ret = ext4_handle_inode_extension(inode, offset, ret, count);
out:
inode_unlock(inode);
if (ret > 0)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9bd80df6b856..071a1f976aab 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3583,53 +3583,7 @@ 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 = {
--
2.20.1
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