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Message-ID: <da556191f9dba2b477cce57665ded57bfd396463.1570100361.git.mbobrowski@mbobrowski.org>
Date: Thu, 3 Oct 2019 21:34:18 +1000
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,
hch@...radead.org, david@...morbit.com, darrick.wong@...cle.com
Subject: [PATCH v4 5/8] ext4: move inode extension/truncate code out from
->iomap_end() callback
In preparation for implementing the iomap direct I/O write path
modifications, the inode extension/truncate code needs to be moved out
from ext4_iomap_end(). For direct I/O, if the current code remained
within ext4_iomap_end() it would behave incorrectly. Updating the
inode size prior to converting unwritten extents to written extents
will potentially allow a racing direct I/O read operation to find
unwritten extents before they've been correctly converted.
The inode extension/truncate code has been moved out into a new helper
ext4_handle_inode_extension(). This function has been designed so that
it can be used by both DAX and direct I/O paths.
Signed-off-by: Matthew Bobrowski <mbobrowski@...browski.org>
---
fs/ext4/file.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++-
fs/ext4/inode.c | 48 +-----------------------------
2 files changed, 79 insertions(+), 48 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 69ac042fb74b..2883711e8a33 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)
{
@@ -233,12 +234,82 @@ 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 offset,
+ ssize_t written, size_t count)
+{
+ int ret = 0;
+ 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 IO 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 and thus
+ * we won't leave uninitialized blocks in a file even if we didn't
+ * succeed in writing as much as we planned.
+ */
+ WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
+ if (offset + count <= EXT4_I(inode)->i_disksize)
+ return written < 0 ? written : 0;
+
+ if (written < 0) {
+ ret = written;
+ goto truncate;
+ }
+
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+ if (IS_ERR(handle)) {
+ ret = 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 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 error;
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)
@@ -255,7 +326,13 @@ 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);
+
+ error = ext4_handle_inode_extension(inode, offset, ret, count);
+ if (error)
+ ret = error;
out:
inode_unlock(inode);
if (ret > 0)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 159ffb92f82d..d616062b603e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3592,53 +3592,7 @@ 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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