This patch introduces a new direct I/O write code path implementation
that makes use of the iomap infrastructure.
All direct I/O write operations are now passed from the ->write_iter()
callback to the new function ext4_dio_write_iter(). This function is
responsible for calling into iomap infrastructure via
iomap_dio_rw(). Snippets of the direct I/O code from within
ext4_file_write_iter(), such as checking whether the IO request is
unaligned asynchronous I/O, or whether it will ber overwriting
allocated and initialized blocks has been moved out and into
ext4_dio_write_iter().
The block mapping flags that are passed to ext4_map_blocks() from
within ext4_dio_get_block() and friends have effectively been taken
out and introduced within the ext4_iomap_alloc().
For inode extension cases, the ->end_io() callback
ext4_dio_write_end_io() is responsible for calling into
ext4_handle_inode_extension() and performing the necessary metadata
updates. Failed writes that we're intended to be extend the inode will
have blocks truncated accordingly. The ->end_io() handler is also
responsible for converting allocated unwritten extents to written
extents.
In the instance of a short write, we fallback to buffered I/O and use
that method to complete whatever is left over in 'iter'. Any blocks
that have been allocated in preparation for direct I/O write will be
reused by buffered I/O, so there's no issue with leaving allocated
blocks beyond EOF.
Existing direct I/O write buffer_head code has been removed as it's
now redundant.
Signed-off-by: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx>
---
fs/ext4/ext4.h | 3 -
fs/ext4/extents.c | 11 +-
fs/ext4/file.c | 245 ++++++++++++++++++---------
fs/ext4/inode.c | 411 +++++-----------------------------------------
4 files changed, 214 insertions(+), 456 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index d0d88f411a44..fdab3420539d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1579,7 +1579,6 @@ enum {
EXT4_STATE_NO_EXPAND, /* No space for expansion */
EXT4_STATE_DA_ALLOC_CLOSE, /* Alloc DA blks on close */
EXT4_STATE_EXT_MIGRATE, /* Inode is migrating */
- EXT4_STATE_DIO_UNWRITTEN, /* need convert on dio done*/
EXT4_STATE_NEWENTRY, /* File just added to dir */
EXT4_STATE_MAY_INLINE_DATA, /* may have in-inode data */
EXT4_STATE_EXT_PRECACHED, /* extents have been precached */
@@ -2560,8 +2559,6 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create);
int ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create);
-int ext4_dio_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create);
int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create);
int ext4_walk_page_buffers(handle_t *handle,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index fb0f99dc8c22..df0629de3667 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1753,16 +1753,9 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
*/
if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
return 0;
- /*
- * The check for IO to unwritten extent is somewhat racy as we
- * increment i_unwritten / set EXT4_STATE_DIO_UNWRITTEN only after
- * dropping i_data_sem. But reserved blocks should save us in that
- * case.
- */
+
if (ext4_ext_is_unwritten(ex1) &&
- (ext4_test_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN) ||
- atomic_read(&EXT4_I(inode)->i_unwritten) ||
- (ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN)))
+ ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN)
return 0;
#ifdef AGGRESSIVE_TEST
if (ext1_ee_len >= 4)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index f64da0c590b2..a6ad747709cf 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -29,6 +29,7 @@
#include <linux/pagevec.h>
#include <linux/uio.h>
#include <linux/mman.h>
+#include <linux/backing-dev.h>
#include "ext4.h"
#include "ext4_jbd2.h"
#include "xattr.h"
@@ -154,13 +155,6 @@ static int ext4_release_file(struct inode *inode, struct file *filp)
return 0;
}
-static void ext4_unwritten_wait(struct inode *inode)
-{
- wait_queue_head_t *wq = ext4_ioend_wq(inode);
-
- wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
-}
-
/*
* This tests whether the IO in question is block-aligned or not.
* Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
@@ -213,13 +207,13 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
struct inode *inode = file_inode(iocb->ki_filp);
ssize_t ret;
+ if (unlikely(IS_IMMUTABLE(inode)))
+ return -EPERM;
+
ret = generic_write_checks(iocb, from);
if (ret <= 0)
return ret;
- if (unlikely(IS_IMMUTABLE(inode)))
- return -EPERM;
-
/*
* If we have encountered a bitmap-format file, the size limit
* is smaller than s_maxbytes, which is for extent-mapped files.
@@ -231,9 +225,39 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
return -EFBIG;
iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
}
+
+ ret = file_modified(iocb->ki_filp);
+ if (ret)
+ return ret;
return iov_iter_count(from);
}
+static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
+ struct iov_iter *from)
+{
+ ssize_t ret;
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
+ inode_lock(inode);
+ ret = ext4_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out;
+
+ current->backing_dev_info = inode_to_bdi(inode);
+ ret = generic_perform_write(iocb->ki_filp, from, iocb->ki_pos);
+ current->backing_dev_info = NULL;
+out:
+ inode_unlock(inode);
+ if (likely(ret > 0)) {
+ iocb->ki_pos += ret;
+ ret = generic_write_sync(iocb, ret);
+ }
+ return ret;
+}
+
static int ext4_handle_inode_extension(struct inode *inode, loff_t offset,
ssize_t written, size_t count)
{
@@ -301,34 +325,77 @@ static int ext4_handle_inode_extension(struct inode *inode, loff_t offset,
return ret;
}
-#ifdef CONFIG_FS_DAX
-static ssize_t
-ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
+ int error, unsigned int flags)
+{
+ loff_t offset = iocb->ki_pos;
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ if (!error && (flags & IOMAP_DIO_UNWRITTEN))
+ error = ext4_convert_unwritten_extents(NULL, inode, offset,
+ size);
+ return ext4_handle_inode_extension(inode, offset, error ? : size,
+ size);
+}
+
+static const struct iomap_dio_ops ext4_dio_write_ops = {
+ .end_io = ext4_dio_write_end_io,
+};
+
+static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
- int error;
ssize_t ret;
size_t count;
loff_t offset;
handle_t *handle;
struct inode *inode = file_inode(iocb->ki_filp);
+ bool extend = false, overwrite = false, unaligned_aio = false;
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
return -EAGAIN;
inode_lock(inode);
}
+
+ if (!ext4_dio_supported(inode)) {
+ inode_unlock(inode);
+ /*
+ * Fallback to buffered I/O if the operation on the
+ * inode is not supported by direct I/O.
+ */
+ return ext4_buffered_write_iter(iocb, from);
+ }
+
ret = ext4_write_checks(iocb, from);
- if (ret <= 0)
- goto out;
- ret = file_remove_privs(iocb->ki_filp);
- if (ret)
- goto out;
- ret = file_update_time(iocb->ki_filp);
- if (ret)
- goto out;
+ if (ret <= 0) {
+ inode_unlock(inode);
+ return ret;
+ }
+ /*
+ * Unaligned direct asynchronous I/O must be serialized among
+ * each other as the zeroing of partial blocks of two
+ * competing unaligned asynchronous I/O writes can result in
+ * data corruption.
+ */
offset = iocb->ki_pos;
count = iov_iter_count(from);
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
+ !is_sync_kiocb(iocb) && ext4_unaligned_aio(inode, from, offset)) {
+ unaligned_aio = true;
+ inode_dio_wait(inode);
+ }
+
+ /*
+ * Determine whether the I/O will overwrite allocated and
+ * initialized blocks. If so, check to see whether it is
+ * possible to take the dioread_nolock path.
+ */
+ if (!unaligned_aio && ext4_overwrite_io(inode, offset, count) &&
+ ext4_should_dioread_nolock(inode)) {
+ overwrite = true;
+ downgrade_write(&inode->i_rwsem);
+ }
if (offset + count > EXT4_I(inode)->i_disksize) {
handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
@@ -342,38 +409,64 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
ext4_journal_stop(handle);
goto out;
}
+
+ extend = true;
ext4_journal_stop(handle);
}
- ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
+ ret = iomap_dio_rw(iocb, from, &ext4_iomap_ops, &ext4_dio_write_ops);
- error = ext4_handle_inode_extension(inode, offset, ret, count);
- if (error)
- ret = error;
+ /*
+ * Unaligned direct asynchronous I/O must be the only I/O in
+ * flight or else any overlapping aligned I/O after unaligned
+ * I/O might result in data corruption. We also need to wait
+ * here in the case where the inode is being extended so that
+ * inode extension routines in the ->end_io handler are
+ * covered by the inode_lock().
+ */
+ if (ret == -EIOCBQUEUED && (unaligned_aio || extend))
+ inode_dio_wait(inode);
+
+ /*
+ * The ->end_io handler may have failed to remove the inode
+ * from the orphan list in the case that the i_disksize got
+ * updated due to a delalloc writeback while the direct I/O
+ * was running.
+ */
+ if (extend && !list_empty(&EXT4_I(inode)->i_orphan)) {
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ if (inode->i_nlink)
+ ext4_orphan_del(NULL, inode);
+ goto out;
+ }
+
+ if (inode->i_nlink)
+ ext4_orphan_del(handle, inode);
+ ext4_journal_stop(handle);
+ }
out:
- inode_unlock(inode);
- if (ret > 0)
- ret = generic_write_sync(iocb, ret);
+ if (overwrite)
+ inode_unlock_shared(inode);
+ else
+ inode_unlock(inode);
+
+ if (ret >= 0 && iov_iter_count(from))
+ return ext4_buffered_write_iter(iocb, from);
return ret;
}
-#endif
+#ifdef CONFIG_FS_DAX
static ssize_t
-ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
- struct inode *inode = file_inode(iocb->ki_filp);
- int o_direct = iocb->ki_flags & IOCB_DIRECT;
- int unaligned_aio = 0;
- int overwrite = 0;
+ int error;
ssize_t ret;
-
- if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
- return -EIO;
-
-#ifdef CONFIG_FS_DAX
- if (IS_DAX(inode))
- return ext4_dax_write_iter(iocb, from);
-#endif
+ size_t count;
+ loff_t offset;
+ handle_t *handle;
+ struct inode *inode = file_inode(iocb->ki_filp);
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
@@ -385,48 +478,50 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (ret <= 0)
goto out;
- /*
- * Unaligned direct AIO must be serialized among each other as zeroing
- * of partial blocks of two competing unaligned AIOs can result in data
- * corruption.
- */
- if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
- !is_sync_kiocb(iocb) &&
- ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
- unaligned_aio = 1;
- ext4_unwritten_wait(inode);
- }
+ offset = iocb->ki_pos;
+ count = iov_iter_count(from);
+ if (offset + count > EXT4_I(inode)->i_disksize) {
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out;
+ }
- iocb->private = &overwrite;
- /* Check whether we do a DIO overwrite or not */
- if (o_direct && !unaligned_aio) {
- if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
- if (ext4_should_dioread_nolock(inode))
- overwrite = 1;
- } else if (iocb->ki_flags & IOCB_NOWAIT) {
- ret = -EAGAIN;
+ ret = ext4_orphan_add(handle, inode);
+ if (ret) {
+ ext4_journal_stop(handle);
goto out;
}
+ ext4_journal_stop(handle);
}
- ret = __generic_file_write_iter(iocb, from);
- /*
- * Unaligned direct AIO must be the only IO in flight. Otherwise
- * overlapping aligned IO after unaligned might result in data
- * corruption.
- */
- if (ret == -EIOCBQUEUED && unaligned_aio)
- ext4_unwritten_wait(inode);
- inode_unlock(inode);
+ 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)
ret = generic_write_sync(iocb, ret);
-
return ret;
+}
+#endif
-out:
- inode_unlock(inode);
- return ret;
+static ssize_t
+ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+ return -EIO;
+
+ if (IS_DAX(inode))
+ return ext4_dax_write_iter(iocb, from);
+
+ if (iocb->ki_flags & IOCB_DIRECT)
+ return ext4_dio_write_iter(iocb, from);
+ return ext4_buffered_write_iter(iocb, from);
}
#ifdef CONFIG_FS_DAX
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 63ad23ae05b8..83c5daf7e0c4 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -826,133 +826,6 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
-/*
- * Get blocks function for the cases that need to start a transaction -
- * generally difference cases of direct IO and DAX IO. It also handles retries
- * in case of ENOSPC.
- */
-static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int flags)
-{
- int dio_credits;
- handle_t *handle;
- int retries = 0;
- int ret;
-
- /* Trim mapping request to maximum we can map at once for DIO */
- if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
- bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
- dio_credits = ext4_chunk_trans_blocks(inode,
- bh_result->b_size >> inode->i_blkbits);
-retry:
- handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
- if (IS_ERR(handle))
- return PTR_ERR(handle);
-
- ret = _ext4_get_block(inode, iblock, bh_result, flags);
- ext4_journal_stop(handle);
-
- if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
- goto retry;
- return ret;
-}
-
-/* Get block function for DIO reads and writes to inodes without extents */
-int ext4_dio_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh, int create)
-{
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
- return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
-}
-
-/*
- * Get block function for AIO DIO writes when we create unwritten extent if
- * blocks are not allocated yet. The extent will be converted to written
- * after IO is complete.
- */
-static int ext4_dio_get_block_unwritten_async(struct inode *inode,
- sector_t iblock, struct buffer_head *bh_result, int create)
-{
- int ret;
-
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- ret = ext4_get_block_trans(inode, iblock, bh_result,
- EXT4_GET_BLOCKS_IO_CREATE_EXT);
-
- /*
- * When doing DIO using unwritten extents, we need io_end to convert
- * unwritten extents to written on IO completion. We allocate io_end
- * once we spot unwritten extent and store it in b_private. Generic
- * DIO code keeps b_private set and furthermore passes the value to
- * our completion callback in 'private' argument.
- */
- if (!ret && buffer_unwritten(bh_result)) {
- if (!bh_result->b_private) {
- ext4_io_end_t *io_end;
-
- io_end = ext4_init_io_end(inode, GFP_KERNEL);
- if (!io_end)
- return -ENOMEM;
- bh_result->b_private = io_end;
- ext4_set_io_unwritten_flag(inode, io_end);
- }
- set_buffer_defer_completion(bh_result);
- }
-
- return ret;
-}
-
-/*
- * Get block function for non-AIO DIO writes when we create unwritten extent if
- * blocks are not allocated yet. The extent will be converted to written
- * after IO is complete by ext4_direct_IO_write().
- */
-static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
- sector_t iblock, struct buffer_head *bh_result, int create)
-{
- int ret;
-
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- ret = ext4_get_block_trans(inode, iblock, bh_result,
- EXT4_GET_BLOCKS_IO_CREATE_EXT);
-
- /*
- * Mark inode as having pending DIO writes to unwritten extents.
- * ext4_direct_IO_write() checks this flag and converts extents to
- * written.
- */
- if (!ret && buffer_unwritten(bh_result))
- ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
-
- return ret;
-}
-
-static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
-{
- int ret;
-
- ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
- inode->i_ino, create);
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- ret = _ext4_get_block(inode, iblock, bh_result, 0);
- /*
- * Blocks should have been preallocated! ext4_file_write_iter() checks
- * that.
- */
- WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
-
- return ret;
-}
-
-
/*
* `handle' can be NULL if create is zero
*/
@@ -3518,7 +3391,8 @@ static int ext4_iomap_alloc(struct inode *inode,
struct ext4_map_blocks *map)
{
handle_t *handle;
- int ret, dio_credits, retries = 0;
+ u8 blkbits = inode->i_blkbits;
+ int ret, dio_credits, m_flags = 0, retries = 0;
/*
* Trim mapping request to the maximum value that we can map
@@ -3538,7 +3412,34 @@ static int ext4_iomap_alloc(struct inode *inode,
if (IS_ERR(handle))
return PTR_ERR(handle);
- ret = ext4_map_blocks(handle, inode, map, EXT4_GET_BLOCKS_CREATE_ZERO);
+ /*
+ * DAX and direct I/O are the only two operations that are
+ * currently supported with IOMAP_WRITE.
+ */
+ WARN_ON(!IS_DAX(inode) && !(flags & IOMAP_DIRECT));
+ if (IS_DAX(inode))
+ m_flags = EXT4_GET_BLOCKS_CREATE_ZERO;
+ /*
+ * We use i_size instead of i_disksize here because delalloc
+ * writeback can complete at any point and subsequently push
+ * the i_disksize out to i_size. This could be beyond where
+ * the direct I/O is happening and thus expose allocated
+ * blocks to direct I/O reads.
+ */
+ else if ((first_block * (1 << blkbits)) >= i_size_read(inode))
+ m_flags = EXT4_GET_BLOCKS_CREATE;
+ else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+ m_flags = EXT4_GET_BLOCKS_IO_CREATE_EXT;
+
+ ret = ext4_map_blocks(handle, inode, map, m_flags);
+
+ /*
+ * We cannot fill holes in indirect tree based inodes as that
+ * could expose stale data in the case of a crash. Use the
+ * magic error code to fallback to buffered I/O.
+ */
+ if (!m_flags && !ret)
+ ret = -ENOTBLK;
ext4_journal_stop(handle);
if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
@@ -3580,6 +3481,15 @@ 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)
{
+ /*
+ * Check to see whether an error occurred while writing out
+ * data to the allocated blocks. If so, return the magic error
+ * code so that we fallback to buffered I/O. Any blocks that
+ * have been allocated in preparation for the direct I/O write
+ * will be reused during buffered I/O.
+ */
+ if (flags & (IOMAP_WRITE | IOMAP_DIRECT) && written == 0)
+ return -ENOTBLK;
return 0;
}
@@ -3588,243 +3498,6 @@ const struct iomap_ops ext4_iomap_ops = {
.iomap_end = ext4_iomap_end,
};
-static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
- ssize_t size, void *private)
-{
- ext4_io_end_t *io_end = private;
-
- /* if not async direct IO just return */
- if (!io_end)
- return 0;
-
- ext_debug("ext4_end_io_dio(): io_end 0x%p "
- "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
- io_end, io_end->inode->i_ino, iocb, offset, size);
-
- /*
- * Error during AIO DIO. We cannot convert unwritten extents as the
- * data was not written. Just clear the unwritten flag and drop io_end.
- */
- if (size <= 0) {
- ext4_clear_io_unwritten_flag(io_end);
- size = 0;
- }
- io_end->offset = offset;
- io_end->size = size;
- ext4_put_io_end(io_end);
-
- return 0;
-}
-
-/*
- * Handling of direct IO writes.
- *
- * For ext4 extent files, ext4 will do direct-io write even to holes,
- * preallocated extents, and those write extend the file, no need to
- * fall back to buffered IO.
- *
- * For holes, we fallocate those blocks, mark them as unwritten
- * If those blocks were preallocated, we mark sure they are split, but
- * still keep the range to write as unwritten.
- *
- * The unwritten extents will be converted to written when DIO is completed.
- * For async direct IO, since the IO may still pending when return, we
- * set up an end_io call back function, which will do the conversion
- * when async direct IO completed.
- *
- * If the O_DIRECT write will extend the file then add this inode to the
- * orphan list. So recovery will truncate it back to the original size
- * if the machine crashes during the write.
- *
- */
-static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- struct ext4_inode_info *ei = EXT4_I(inode);
- ssize_t ret;
- loff_t offset = iocb->ki_pos;
- size_t count = iov_iter_count(iter);
- int overwrite = 0;
- get_block_t *get_block_func = NULL;
- int dio_flags = 0;
- loff_t final_size = offset + count;
- int orphan = 0;
- handle_t *handle;
-
- if (final_size > inode->i_size || final_size > ei->i_disksize) {
- /* Credits for sb + inode write */
- handle = ext4_journal_start(inode, EXT4_HT_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;
- }
- orphan = 1;
- ext4_update_i_disksize(inode, inode->i_size);
- ext4_journal_stop(handle);
- }
-
- BUG_ON(iocb->private == NULL);
-
- /*
- * Make all waiters for direct IO properly wait also for extent
- * conversion. This also disallows race between truncate() and
- * overwrite DIO as i_dio_count needs to be incremented under i_mutex.
- */
- inode_dio_begin(inode);
-
- /* If we do a overwrite dio, i_mutex locking can be released */
- overwrite = *((int *)iocb->private);
-
- if (overwrite)
- inode_unlock(inode);
-
- /*
- * For extent mapped files we could direct write to holes and fallocate.
- *
- * Allocated blocks to fill the hole are marked as unwritten 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 unwritten.
- *
- * For non AIO case, we will convert those unwritten extents to written
- * after return back from blockdev_direct_IO. That way we save us from
- * allocating io_end structure and also the overhead of offloading
- * the extent convertion to a workqueue.
- *
- * For async DIO, the conversion needs to be deferred 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;
- if (overwrite)
- get_block_func = ext4_dio_get_block_overwrite;
- else if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
- round_down(offset, i_blocksize(inode)) >= inode->i_size) {
- get_block_func = ext4_dio_get_block;
- dio_flags = DIO_LOCKING | DIO_SKIP_HOLES;
- } else if (is_sync_kiocb(iocb)) {
- get_block_func = ext4_dio_get_block_unwritten_sync;
- dio_flags = DIO_LOCKING;
- } else {
- get_block_func = ext4_dio_get_block_unwritten_async;
- dio_flags = DIO_LOCKING;
- }
- ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
- get_block_func, ext4_end_io_dio, NULL,
- dio_flags);
-
- if (ret > 0 && !overwrite && 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(NULL, inode,
- offset, ret);
- if (err < 0)
- ret = err;
- ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
- }
-
- inode_dio_end(inode);
- /* take i_mutex locking again if we do a ovewrite dio */
- if (overwrite)
- inode_lock(inode);
-
- if (ret < 0 && final_size > inode->i_size)
- ext4_truncate_failed_write(inode);
-
- /* Handle extending of i_size after direct IO write */
- if (orphan) {
- int err;
-
- /* Credits for sb + inode write */
- handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
- if (IS_ERR(handle)) {
- /*
- * We wrote the data but cannot extend
- * i_size. Bail out. In async io case, we do
- * not return error here because we have
- * already submmitted the corresponding
- * bio. Returning error here makes the caller
- * think that this IO is done and failed
- * resulting in race with bio's completion
- * handler.
- */
- if (!ret)
- 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 || end > ei->i_disksize) {
- ext4_update_i_disksize(inode, end);
- if (end > inode->i_size)
- 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;
-}
-
-static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- size_t count = iov_iter_count(iter);
- loff_t offset = iocb->ki_pos;
- ssize_t ret;
-
-#ifdef CONFIG_FS_ENCRYPTION
- if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
- return 0;
-#endif
- if (fsverity_active(inode))
- return 0;
-
- /*
- * If we are doing data journalling we don't support O_DIRECT
- */
- if (ext4_should_journal_data(inode))
- return 0;
-
- /* Let buffer I/O handle the inline data case. */
- if (ext4_has_inline_data(inode))
- return 0;
-
- trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
- ret = ext4_direct_IO_write(iocb, iter);
- trace_ext4_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), 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
@@ -3862,7 +3535,7 @@ static const struct address_space_operations ext4_aops = {
.bmap = ext4_bmap,
.invalidatepage = ext4_invalidatepage,
.releasepage = ext4_releasepage,
- .direct_IO = ext4_direct_IO,
+ .direct_IO = noop_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
@@ -3879,7 +3552,7 @@ static const struct address_space_operations ext4_journalled_aops = {
.bmap = ext4_bmap,
.invalidatepage = ext4_journalled_invalidatepage,
.releasepage = ext4_releasepage,
- .direct_IO = ext4_direct_IO,
+ .direct_IO = noop_direct_IO,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
};
@@ -3895,7 +3568,7 @@ static const struct address_space_operations ext4_da_aops = {
.bmap = ext4_bmap,
.invalidatepage = ext4_invalidatepage,
.releasepage = ext4_releasepage,
- .direct_IO = ext4_direct_IO,
+ .direct_IO = noop_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
--
2.20.1
