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Subject[RFC PATCH 20/22] ext4: add support for read_iter, write_iter, and direct_IO_bvec
Date
Some helpers were broken out of ext4_ind_direct_IO() and
ext4_ext_direct_IO() in order to avoid code duplication in new
bio_vec-based functions.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Zach Brown <zab@zabbo.net>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: linux-ext4@vger.kernel.org
---
fs/ext4/ext4.h | 3 +
fs/ext4/file.c | 2 +
fs/ext4/indirect.c | 169 +++++++++++++++++++++++++++++++-----------
fs/ext4/inode.c | 206 +++++++++++++++++++++++++++++++++++-----------------
4 files changed, 268 insertions(+), 112 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 513004f..6426d43 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1905,6 +1905,9 @@ extern int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
extern ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs);
+extern ssize_t ext4_ind_direct_IO_bvec(int rw, struct kiocb *iocb,
+ struct bio_vec *bvec, loff_t offset,
+ unsigned long bvec_len);
extern int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock);
extern int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk);
extern void ext4_ind_truncate(struct inode *inode);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index cb70f18..ce76745 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -234,6 +234,8 @@ const struct file_operations ext4_file_operations = {
.write = do_sync_write,
.aio_read = generic_file_aio_read,
.aio_write = ext4_file_write,
+ .read_iter = generic_file_read_iter,
+ .write_iter = generic_file_write_iter,
.unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ext4_compat_ioctl,
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 830e1b2..e8ca3b9 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -760,6 +760,72 @@ out:
return err;
}

+static ssize_t ext4_journal_orphan_add(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ handle_t *handle;
+ ssize_t ret;
+
+ /* Credits for sb + inode write */
+ handle = ext4_journal_start(inode, 2);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out;
+ }
+ ret = ext4_orphan_add(handle, inode);
+ if (ret) {
+ ext4_journal_stop(handle);
+ goto out;
+ }
+ ei->i_disksize = inode->i_size;
+ ext4_journal_stop(handle);
+out:
+ return ret;
+}
+
+static ssize_t ext4_journal_orphan_del(struct inode *inode, ssize_t ret,
+ loff_t offset)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ handle_t *handle;
+ int err;
+
+ /* Credits for sb + inode write */
+ handle = ext4_journal_start(inode, 2);
+ if (IS_ERR(handle)) {
+ /* This is really bad luck. We've written the data
+ * but cannot extend i_size. Bail out and pretend
+ * the write failed... */
+ ret = PTR_ERR(handle);
+ if (inode->i_nlink)
+ ext4_orphan_del(NULL, inode);
+
+ goto out;
+ }
+ if (inode->i_nlink)
+ ext4_orphan_del(handle, inode);
+ if (ret > 0) {
+ loff_t end = offset + ret;
+ if (end > inode->i_size) {
+ ei->i_disksize = end;
+ i_size_write(inode, end);
+ /*
+ * We're going to return a positive `ret'
+ * here due to non-zero-length I/O, so there's
+ * no way of reporting error returns from
+ * ext4_mark_inode_dirty() to userspace. So
+ * ignore it.
+ */
+ ext4_mark_inode_dirty(handle, inode);
+ }
+ }
+ err = ext4_journal_stop(handle);
+ if (ret == 0)
+ ret = err;
+out:
+ return ret;
+}
+
/*
* O_DIRECT for ext3 (or indirect map) based files
*
@@ -778,7 +844,6 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct ext4_inode_info *ei = EXT4_I(inode);
- handle_t *handle;
ssize_t ret;
int orphan = 0;
size_t count = iov_length(iov, nr_segs);
@@ -788,20 +853,10 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
loff_t final_size = offset + count;

if (final_size > inode->i_size) {
- /* Credits for sb + inode write */
- handle = ext4_journal_start(inode, 2);
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- goto out;
- }
- ret = ext4_orphan_add(handle, inode);
- if (ret) {
- ext4_journal_stop(handle);
+ ret = ext4_journal_orphan_add(inode);
+ if (ret)
goto out;
- }
orphan = 1;
- ei->i_disksize = inode->i_size;
- ext4_journal_stop(handle);
}
}

@@ -831,42 +886,68 @@ retry:
if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;

- if (orphan) {
- int err;
+ if (orphan)
+ ret = ext4_journal_orphan_del(inode, ret, offset);
+out:
+ return ret;
+}

- /* Credits for sb + inode write */
- handle = ext4_journal_start(inode, 2);
- if (IS_ERR(handle)) {
- /* This is really bad luck. We've written the data
- * but cannot extend i_size. Bail out and pretend
- * the write failed... */
- ret = PTR_ERR(handle);
- if (inode->i_nlink)
- ext4_orphan_del(NULL, inode);
+/*
+ * Like ext4_ind_direct_IO, but operates on bio_vec instead of iovec
+ */
+ssize_t ext4_ind_direct_IO_bvec(int rw, struct kiocb *iocb,
+ struct bio_vec *bvec, loff_t offset,
+ unsigned long bvec_len)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ ssize_t ret;
+ int orphan = 0;
+ size_t count = bvec_length(bvec, bvec_len);
+ int retries = 0;
+
+ if (rw == WRITE) {
+ loff_t final_size = offset + count;

- goto out;
+ if (final_size > inode->i_size) {
+ ret = ext4_journal_orphan_add(inode);
+ if (ret)
+ goto out;
+ orphan = 1;
}
- if (inode->i_nlink)
- ext4_orphan_del(handle, inode);
- if (ret > 0) {
- loff_t end = offset + ret;
- if (end > inode->i_size) {
- ei->i_disksize = end;
- i_size_write(inode, end);
- /*
- * We're going to return a positive `ret'
- * here due to non-zero-length I/O, so there's
- * no way of reporting error returns from
- * ext4_mark_inode_dirty() to userspace. So
- * ignore it.
- */
- ext4_mark_inode_dirty(handle, inode);
- }
+ }
+
+retry:
+ if (rw == READ && ext4_should_dioread_nolock(inode)) {
+ if (unlikely(!list_empty(&ei->i_completed_io_list))) {
+ mutex_lock(&inode->i_mutex);
+ ext4_flush_completed_IO(inode);
+ mutex_unlock(&inode->i_mutex);
+ }
+ ret = __blockdev_direct_IO_bvec(rw, iocb, inode,
+ inode->i_sb->s_bdev, bvec,
+ offset, bvec_len,
+ ext4_get_block, NULL, NULL, 0);
+ } else {
+ ret = blockdev_direct_IO_bvec(rw, iocb, inode,
+ inode->i_sb->s_bdev, bvec,
+ offset, bvec_len,
+ ext4_get_block, NULL);
+
+ if (unlikely((rw & WRITE) && ret < 0)) {
+ loff_t isize = i_size_read(inode);
+ loff_t end = offset + bvec_length(bvec, bvec_len);
+
+ if (end > isize)
+ ext4_truncate_failed_write(inode);
}
- err = ext4_journal_stop(handle);
- if (ret == 0)
- ret = err;
}
+ if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+ goto retry;
+
+ if (orphan)
+ ret = ext4_journal_orphan_del(inode, ret, offset);
out:
return ret;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index feaa82f..922b26f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2764,7 +2764,7 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,

ext_debug("ext4_end_io_dio(): io_end 0x%p "
"for inode %lu, iocb 0x%p, offset %llu, size %llu\n",
- iocb->private, io_end->inode->i_ino, iocb, offset,
+ iocb->private, io_end->inode->i_ino, iocb, offset,
size);

iocb->private = NULL;
@@ -2868,6 +2868,85 @@ retry:
return 0;
}

+static ssize_t ext4_ext_direct_IO_pre_write(struct kiocb *iocb,
+ struct inode *inode)
+{
+ /*
+ * We could direct write to holes and fallocate.
+ *
+ * Allocated blocks to fill the hole are marked as uninitialized
+ * to prevent parallel buffered read to expose the stale data
+ * before DIO complete the data IO.
+ *
+ * As to previously fallocated extents, ext4 get_block
+ * will just simply mark the buffer mapped but still
+ * keep the extents uninitialized.
+ *
+ * for non AIO case, we will convert those unwritten extents
+ * to written after return back from blockdev_direct_IO.
+ *
+ * for async DIO, the conversion needs to be defered when
+ * the IO is completed. The ext4 end_io callback function
+ * will be called to take care of the conversion work.
+ * Here for async case, we allocate an io_end structure to
+ * hook to the iocb.
+ */
+ iocb->private = NULL;
+ EXT4_I(inode)->cur_aio_dio = NULL;
+ if (!is_sync_kiocb(iocb)) {
+ iocb->private = ext4_init_io_end(inode, GFP_NOFS);
+ if (!iocb->private)
+ return -ENOMEM;
+ /*
+ * we save the io structure for current async
+ * direct IO, so that later ext4_map_blocks()
+ * could flag the io structure whether there
+ * is a unwritten extents needs to be converted
+ * when IO is completed.
+ */
+ EXT4_I(inode)->cur_aio_dio = iocb->private;
+ }
+ return 0;
+}
+
+static ssize_t ext4_ext_direct_IO_post_write(struct kiocb *iocb,
+ struct inode *inode,
+ loff_t offset, ssize_t ret)
+{
+ if (iocb->private)
+ EXT4_I(inode)->cur_aio_dio = NULL;
+ /*
+ * The io_end structure takes a reference to the inode,
+ * that structure needs to be destroyed and the
+ * reference to the inode need to be dropped, when IO is
+ * complete, even with 0 byte write, or failed.
+ *
+ * In the successful AIO DIO case, the io_end structure will be
+ * desctroyed and the reference to the inode will be dropped
+ * after the end_io call back function is called.
+ *
+ * In the case there is 0 byte write, or error case, since
+ * VFS direct IO won't invoke the end_io call back function,
+ * we need to free the end_io structure here.
+ */
+ if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
+ ext4_free_io_end(iocb->private);
+ iocb->private = NULL;
+ } else if (ret > 0 &&
+ ext4_test_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN)) {
+ int err;
+ /*
+ * for non AIO case, since the IO is already
+ * completed, we could do the conversion right here
+ */
+ err = ext4_convert_unwritten_extents(inode, offset, ret);
+ if (err < 0)
+ ret = err;
+ ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
+ }
+ return ret;
+}
+
/*
* For ext4 extent files, ext4 will do direct-io write to holes,
* preallocated extents, and those write extend the file, no need to
@@ -2898,41 +2977,9 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,

loff_t final_size = offset + count;
if (rw == WRITE && final_size <= inode->i_size) {
- /*
- * We could direct write to holes and fallocate.
- *
- * Allocated blocks to fill the hole are marked as uninitialized
- * to prevent parallel buffered read to expose the stale data
- * before DIO complete the data IO.
- *
- * As to previously fallocated extents, ext4 get_block
- * will just simply mark the buffer mapped but still
- * keep the extents uninitialized.
- *
- * for non AIO case, we will convert those unwritten extents
- * to written after return back from blockdev_direct_IO.
- *
- * for async DIO, the conversion needs to be defered when
- * the IO is completed. The ext4 end_io callback function
- * will be called to take care of the conversion work.
- * Here for async case, we allocate an io_end structure to
- * hook to the iocb.
- */
- iocb->private = NULL;
- EXT4_I(inode)->cur_aio_dio = NULL;
- if (!is_sync_kiocb(iocb)) {
- iocb->private = ext4_init_io_end(inode, GFP_NOFS);
- if (!iocb->private)
- return -ENOMEM;
- /*
- * we save the io structure for current async
- * direct IO, so that later ext4_map_blocks()
- * could flag the io structure whether there
- * is a unwritten extents needs to be converted
- * when IO is completed.
- */
- EXT4_I(inode)->cur_aio_dio = iocb->private;
- }
+ ret = ext4_ext_direct_IO_pre_write(iocb, inode);
+ if (ret)
+ return ret;

ret = __blockdev_direct_IO(rw, iocb, inode,
inode->i_sb->s_bdev, iov,
@@ -2941,38 +2988,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
ext4_end_io_dio,
NULL,
DIO_LOCKING | DIO_SKIP_HOLES);
- if (iocb->private)
- EXT4_I(inode)->cur_aio_dio = NULL;
- /*
- * The io_end structure takes a reference to the inode,
- * that structure needs to be destroyed and the
- * reference to the inode need to be dropped, when IO is
- * complete, even with 0 byte write, or failed.
- *
- * In the successful AIO DIO case, the io_end structure will be
- * desctroyed and the reference to the inode will be dropped
- * after the end_io call back function is called.
- *
- * In the case there is 0 byte write, or error case, since
- * VFS direct IO won't invoke the end_io call back function,
- * we need to free the end_io structure here.
- */
- if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
- ext4_free_io_end(iocb->private);
- iocb->private = NULL;
- } else if (ret > 0 && ext4_test_inode_state(inode,
- EXT4_STATE_DIO_UNWRITTEN)) {
- int err;
- /*
- * for non AIO case, since the IO is already
- * completed, we could do the conversion right here
- */
- err = ext4_convert_unwritten_extents(inode,
- offset, ret);
- if (err < 0)
- ret = err;
- ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
- }
+ ret = ext4_ext_direct_IO_post_write(iocb, inode, offset, ret);
return ret;
}

@@ -2980,6 +2996,37 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
}

+/*
+ * Like ext4_ext_direct_IO, but operates on a bio_vec rather than iovec.
+ */
+static ssize_t ext4_ext_direct_IO_bvec(int rw, struct kiocb *iocb,
+ struct bio_vec *bvec, loff_t offset,
+ unsigned long bvec_len)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ ssize_t ret;
+ size_t count = bvec_length(bvec, bvec_len);
+
+ loff_t final_size = offset + count;
+ if (rw == WRITE && final_size <= inode->i_size) {
+ ret = ext4_ext_direct_IO_pre_write(iocb, inode);
+ if (ret)
+ return ret;
+
+ ret = blockdev_direct_IO_bvec(rw, iocb, inode,
+ inode->i_sb->s_bdev, bvec,
+ offset, bvec_len,
+ ext4_get_block_write,
+ ext4_end_io_dio);
+ ret = ext4_ext_direct_IO_post_write(iocb, inode, offset, ret);
+ return ret;
+ }
+
+ /* for write the the end of file case, we fall back to old way */
+ return ext4_ind_direct_IO_bvec(rw, iocb, bvec, offset, bvec_len);
+}
+
static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
@@ -3004,6 +3051,25 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
return ret;
}

+static ssize_t ext4_direct_IO_bvec(int rw, struct kiocb *iocb,
+ struct bio_vec *bvec, loff_t offset,
+ unsigned long bvec_len)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ ssize_t ret;
+
+ trace_ext4_direct_IO_enter(inode, offset, bvec_length(bvec, bvec_len),
+ rw);
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+ ret = ext4_ext_direct_IO_bvec(rw, iocb, bvec, offset, bvec_len);
+ else
+ ret = ext4_ind_direct_IO_bvec(rw, iocb, bvec, offset, bvec_len);
+ trace_ext4_direct_IO_exit(inode, offset, bvec_length(bvec, bvec_len),
+ rw, ret);
+ return ret;
+}
+
/*
* Pages can be marked dirty completely asynchronously from ext4's journalling
* activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do
@@ -3033,6 +3099,7 @@ static const struct address_space_operations ext4_ordered_aops = {
.invalidatepage = ext4_invalidatepage,
.releasepage = ext4_releasepage,
.direct_IO = ext4_direct_IO,
+ .direct_IO_bvec = ext4_direct_IO_bvec,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
@@ -3048,6 +3115,7 @@ static const struct address_space_operations ext4_writeback_aops = {
.invalidatepage = ext4_invalidatepage,
.releasepage = ext4_releasepage,
.direct_IO = ext4_direct_IO,
+ .direct_IO_bvec = ext4_direct_IO_bvec,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
@@ -3064,6 +3132,7 @@ static const struct address_space_operations ext4_journalled_aops = {
.invalidatepage = ext4_invalidatepage,
.releasepage = ext4_releasepage,
.direct_IO = ext4_direct_IO,
+ .direct_IO_bvec = ext4_direct_IO_bvec,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
};
@@ -3079,6 +3148,7 @@ static const struct address_space_operations ext4_da_aops = {
.invalidatepage = ext4_da_invalidatepage,
.releasepage = ext4_releasepage,
.direct_IO = ext4_direct_IO,
+ .direct_IO_bvec = ext4_direct_IO_bvec,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
--
1.7.9.2


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