Call the block I/O layer directly instad of going through the buffer
layer. This should give us much better performance and scalability,
as well as lowering our CPU utilization when doing buffered writeback.
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
---
fs/ext4/Makefile | 2 +-
fs/ext4/ext4.h | 33 +++++-
fs/ext4/extents.c | 4 +-
fs/ext4/inode.c | 118 ++---------------
fs/ext4/page-io.c | 363 +++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/super.c | 8 +-
6 files changed, 419 insertions(+), 109 deletions(-)
create mode 100644 fs/ext4/page-io.c
diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 8867b2a..c947e36 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -4,7 +4,7 @@
obj-$(CONFIG_EXT4_FS) += ext4.o
-ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
+ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2283369..bc1962f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -168,7 +168,18 @@ struct mpage_da_data {
int pages_written;
int retval;
};
-#define EXT4_IO_UNWRITTEN 0x1
+
+/*
+ * Flags for ext4_io_end->flags
+ */
+#define EXT4_IO_END_UNWRITTEN 0x0001
+#define EXT4_IO_END_ERROR 0x0002
+
+struct ext4_io_page {
+ struct page *p_page;
+ struct ext4_io_page *p_next;
+};
+
typedef struct ext4_io_end {
struct list_head list; /* per-file finished IO list */
struct inode *inode; /* file being written to */
@@ -179,8 +190,17 @@ typedef struct ext4_io_end {
struct work_struct work; /* data work queue */
struct kiocb *iocb; /* iocb struct for AIO */
int result; /* error value for AIO */
+ struct ext4_io_page *io_page;
} ext4_io_end_t;
+struct ext4_io_submit {
+ int io_op;
+ struct bio *io_bio;
+ ext4_io_end_t *io_end;
+ struct ext4_io_page *io_page;
+ sector_t io_next_block;
+};
+
/*
* Special inodes numbers
*/
@@ -2044,6 +2064,17 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
__u64 start_orig, __u64 start_donor,
__u64 len, __u64 *moved_len);
+/* page_io.c */
+extern int __init init_ext4_pageio(void);
+extern void exit_ext4_pageio(void);
+extern void ext4_free_io_end(ext4_io_end_t *io);
+extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
+extern int ext4_end_io_nolock(ext4_io_end_t *io);
+extern void ext4_io_submit(struct ext4_io_submit *io);
+extern int ext4_bio_write_page(struct ext4_io_submit *io,
+ struct page *page,
+ int len,
+ struct writeback_control *wbc);
/* BH_Uninit flag: blocks are allocated but uninitialized on disk */
enum ext4_state_bits {
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index a0e6230..a1e20c8 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3202,7 +3202,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
* completed
*/
if (io)
- io->flag = EXT4_IO_UNWRITTEN;
+ io->flag = EXT4_IO_END_UNWRITTEN;
else
ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
if (ext4_should_dioread_nolock(inode))
@@ -3494,7 +3494,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
*/
if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
if (io)
- io->flag = EXT4_IO_UNWRITTEN;
+ io->flag = EXT4_IO_END_UNWRITTEN;
else
ext4_set_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 93668ca..79fdace 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2016,8 +2016,10 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
struct buffer_head *bh, *page_bufs = NULL;
int journal_data = ext4_should_journal_data(inode);
sector_t pblock = 0, cur_logical = 0;
+ struct ext4_io_submit io_submit;
BUG_ON(mpd->next_page <= mpd->first_page);
+ memset(&io_submit, 0, sizeof(io_submit));
/*
* We need to start from the first_page to the next_page - 1
* to make sure we also write the mapped dirty buffer_heads.
@@ -2109,16 +2111,16 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
/* mark the buffer_heads as dirty & uptodate */
block_commit_write(page, 0, len);
- if (journal_data && PageChecked(page))
+ /*
+ * Delalloc doesn't support data journalling,
+ * but eventually maybe we'll lift this
+ * restriction.
+ */
+ if (unlikely(journal_data && PageChecked(page)))
err = __ext4_journalled_writepage(page, len);
- else if (buffer_uninit(page_bufs)) {
- ext4_set_bh_endio(page_bufs, inode);
- err = block_write_full_page_endio(page,
- noalloc_get_block_write,
- mpd->wbc, ext4_end_io_buffer_write);
- } else
- err = block_write_full_page(page,
- noalloc_get_block_write, mpd->wbc);
+ else
+ err = ext4_bio_write_page(&io_submit, page,
+ len, mpd->wbc);
if (!err)
mpd->pages_written++;
@@ -2131,6 +2133,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
}
pagevec_release(&pvec);
}
+ ext4_io_submit(&io_submit);
return ret;
}
@@ -3423,15 +3426,6 @@ ext4_readpages(struct file *file, struct address_space *mapping,
return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
}
-static void ext4_free_io_end(ext4_io_end_t *io)
-{
- BUG_ON(!io);
- if (io->page)
- put_page(io->page);
- iput(io->inode);
- kfree(io);
-}
-
static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
{
struct buffer_head *head, *bh;
@@ -3637,68 +3631,6 @@ static void dump_completed_IO(struct inode * inode)
}
/*
- * check a range of space and convert unwritten extents to written.
- */
-static int ext4_end_io_nolock(ext4_io_end_t *io)
-{
- struct inode *inode = io->inode;
- loff_t offset = io->offset;
- ssize_t size = io->size;
- int ret = 0;
-
- ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
- "list->prev 0x%p\n",
- io, inode->i_ino, io->list.next, io->list.prev);
-
- if (list_empty(&io->list))
- return ret;
-
- if (io->flag != EXT4_IO_UNWRITTEN)
- return ret;
-
- ret = ext4_convert_unwritten_extents(inode, offset, size);
- if (ret < 0) {
- printk(KERN_EMERG "%s: failed to convert unwritten"
- "extents to written extents, error is %d"
- " io is still on inode %lu aio dio list\n",
- __func__, ret, inode->i_ino);
- return ret;
- }
-
- if (io->iocb)
- aio_complete(io->iocb, io->result, 0);
- /* clear the DIO AIO unwritten flag */
- io->flag = 0;
- return ret;
-}
-
-/*
- * work on completed aio dio IO, to convert unwritten extents to extents
- */
-static void ext4_end_io_work(struct work_struct *work)
-{
- ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
- struct inode *inode = io->inode;
- struct ext4_inode_info *ei = EXT4_I(inode);
- unsigned long flags;
- int ret;
-
- mutex_lock(&inode->i_mutex);
- ret = ext4_end_io_nolock(io);
- if (ret < 0) {
- mutex_unlock(&inode->i_mutex);
- return;
- }
-
- spin_lock_irqsave(&ei->i_completed_io_lock, flags);
- if (!list_empty(&io->list))
- list_del_init(&io->list);
- spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
- mutex_unlock(&inode->i_mutex);
- ext4_free_io_end(io);
-}
-
-/*
* This function is called from ext4_sync_file().
*
* When IO is completed, the work to convert unwritten extents to
@@ -3753,28 +3685,6 @@ int flush_completed_IO(struct inode *inode)
return (ret2 < 0) ? ret2 : 0;
}
-static ext4_io_end_t *ext4_init_io_end (struct inode *inode, gfp_t flags)
-{
- ext4_io_end_t *io = NULL;
-
- io = kmalloc(sizeof(*io), flags);
-
- if (io) {
- igrab(inode);
- io->inode = inode;
- io->flag = 0;
- io->offset = 0;
- io->size = 0;
- io->page = NULL;
- io->iocb = NULL;
- io->result = 0;
- INIT_WORK(&io->work, ext4_end_io_work);
- INIT_LIST_HEAD(&io->list);
- }
-
- return io;
-}
-
static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
ssize_t size, void *private, int ret,
bool is_async)
@@ -3794,7 +3704,7 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
size);
/* if not aio dio with unwritten extents, just free io and return */
- if (io_end->flag != EXT4_IO_UNWRITTEN){
+ if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
ext4_free_io_end(io_end);
iocb->private = NULL;
out:
@@ -3839,7 +3749,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
goto out;
}
- io_end->flag = EXT4_IO_UNWRITTEN;
+ io_end->flag = EXT4_IO_END_UNWRITTEN;
inode = io_end->inode;
/* Add the io_end to per-inode completed io list*/
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
new file mode 100644
index 0000000..affd6cc
--- /dev/null
+++ b/fs/ext4/page-io.c
@@ -0,0 +1,363 @@
+/*
+ * linux/fs/ext4/page-io.c
+ *
+ * This contains the new page_io functions for ext4
+ *
+ * Written by Theodore Ts'o, 2010.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/jbd2.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.h>
+#include <linux/quotaops.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/pagevec.h>
+#include <linux/mpage.h>
+#include <linux/namei.h>
+#include <linux/uio.h>
+#include <linux/bio.h>
+#include <linux/workqueue.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "ext4_jbd2.h"
+#include "xattr.h"
+#include "acl.h"
+#include "ext4_extents.h"
+
+static struct kmem_cache *io_page_cachep;
+
+int __init init_ext4_pageio(void)
+{
+ io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
+ if (io_page_cachep == NULL)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void exit_ext4_pageio(void)
+{
+ kmem_cache_destroy(io_page_cachep);
+}
+
+void ext4_free_io_end(ext4_io_end_t *io)
+{
+ struct ext4_io_page *io_page, *next;
+
+ BUG_ON(!io);
+ if (io->page)
+ put_page(io->page);
+ iput(io->inode);
+ for (io_page = io->io_page; io_page; io_page = next) {
+ put_page(io_page->p_page);
+ next = io_page->p_next;
+ kmem_cache_free(io_page_cachep, io_page);
+ }
+ kfree(io);
+}
+
+/*
+ * check a range of space and convert unwritten extents to written.
+ */
+int ext4_end_io_nolock(ext4_io_end_t *io)
+{
+ struct inode *inode = io->inode;
+ loff_t offset = io->offset;
+ ssize_t size = io->size;
+ int ret = 0;
+
+ ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
+ "list->prev 0x%p\n",
+ io, inode->i_ino, io->list.next, io->list.prev);
+
+ if (list_empty(&io->list))
+ return ret;
+
+ if (!(io->flag & EXT4_IO_END_UNWRITTEN))
+ return ret;
+
+ ret = ext4_convert_unwritten_extents(inode, offset, size);
+ if (ret < 0) {
+ printk(KERN_EMERG "%s: failed to convert unwritten"
+ "extents to written extents, error is %d"
+ " io is still on inode %lu aio dio list\n",
+ __func__, ret, inode->i_ino);
+ return ret;
+ }
+
+ if (io->iocb)
+ aio_complete(io->iocb, io->result, 0);
+ /* clear the DIO AIO unwritten flag */
+ io->flag &= ~EXT4_IO_END_UNWRITTEN;
+ return ret;
+}
+
+/*
+ * work on completed aio dio IO, to convert unwritten extents to extents
+ */
+static void ext4_end_io_work(struct work_struct *work)
+{
+ ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
+ struct inode *inode = io->inode;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ unsigned long flags;
+ int ret;
+
+ mutex_lock(&inode->i_mutex);
+ ret = ext4_end_io_nolock(io);
+ if (ret < 0) {
+ mutex_unlock(&inode->i_mutex);
+ return;
+ }
+
+ spin_lock_irqsave(&ei->i_completed_io_lock, flags);
+ if (!list_empty(&io->list))
+ list_del_init(&io->list);
+ spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
+ mutex_unlock(&inode->i_mutex);
+ ext4_free_io_end(io);
+}
+
+ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
+{
+ ext4_io_end_t *io = NULL;
+
+ io = kmalloc(sizeof(*io), flags);
+
+ if (io) {
+ memset(io, 0, sizeof(*io));
+ igrab(inode);
+ io->inode = inode;
+ INIT_WORK(&io->work, ext4_end_io_work);
+ INIT_LIST_HEAD(&io->list);
+ }
+
+ return io;
+}
+
+static void ext4_end_bio(struct bio *bio, int error)
+{
+ ext4_io_end_t *io_end = bio->bi_private;
+ struct workqueue_struct *wq;
+ struct inode *inode;
+ unsigned long flags;
+ struct ext4_io_page *io_page;
+
+ BUG_ON(!io_end);
+ inode = io_end->inode;
+ bio->bi_private = NULL;
+ bio->bi_end_io = NULL;
+ if (test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = 0;
+ bio_put(bio);
+
+ if (!(inode->i_sb->s_flags & MS_ACTIVE)) {
+ printk("sb umounted, discard end_io request for inode %lu\n",
+ io_end->inode->i_ino);
+ ext4_free_io_end(io_end);
+ return;
+ }
+
+ if (error)
+ io_end->flag |= EXT4_IO_END_ERROR;
+
+ for (io_page = io_end->io_page; io_page; io_page = io_page->p_next) {
+ struct page *page = io_page->p_page;
+ struct buffer_head *bh, *head = page_buffers(io_page->p_page);
+
+ if (error)
+ SetPageError(page);
+ BUG_ON(!head);
+ if (head->b_size == PAGE_CACHE_SIZE)
+ clear_buffer_dirty(head);
+ else {
+ /*
+ * If block_size < page_size we need to worry
+ * about partial writes.
+ */
+ loff_t offset;
+ loff_t io_end_offset = io_end->offset + io_end->size;
+ int partial = 0;
+
+ offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
+ bh = head;
+ do {
+ if ((offset >= io_end->offset) &&
+ (offset+bh->b_size <= io_end_offset))
+ clear_buffer_dirty(bh);
+ if (buffer_dirty(bh))
+ partial = 1;
+ offset += bh->b_size;
+ bh = bh->b_this_page;
+ } while (bh != head);
+ if (partial)
+ continue;
+ }
+ end_page_writeback(page);
+ }
+
+ /* Add the io_end to per-inode completed io list*/
+ spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
+ list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
+ spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
+
+ wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
+ /* queue the work to convert unwritten extents to written */
+ queue_work(wq, &io_end->work);
+}
+
+void ext4_io_submit(struct ext4_io_submit *io)
+{
+ struct bio *bio = io->io_bio;
+
+ if (bio) {
+ bio_get(io->io_bio);
+ submit_bio(io->io_op, io->io_bio);
+ BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
+ bio_put(io->io_bio);
+ }
+ io->io_bio = 0;
+ io->io_op = 0;
+ io->io_end = 0;
+}
+
+static int io_submit_init(struct ext4_io_submit *io,
+ struct inode *inode,
+ struct writeback_control *wbc,
+ struct buffer_head *bh)
+{
+ ext4_io_end_t *io_end;
+ struct page *page = bh->b_page;
+ int nvecs = bio_get_nr_vecs(bh->b_bdev);
+ struct bio *bio;
+
+ io_end = ext4_init_io_end(inode, GFP_NOFS);
+ if (!io_end)
+ return -ENOMEM;
+ do {
+
+ bio = bio_alloc(GFP_NOIO, nvecs);
+ nvecs >>= 1;
+ } while (bio == NULL);
+
+ bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+ bio->bi_bdev = bh->b_bdev;
+ bio->bi_private = io->io_end = io_end;
+ bio->bi_end_io = ext4_end_bio;
+
+ io_end->inode = inode;
+ io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
+
+ io->io_bio = bio;
+ io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?
+ WRITE_SYNC_PLUG : WRITE);
+ io->io_next_block = bh->b_blocknr;
+ return 0;
+}
+
+static int io_submit_add_bh(struct ext4_io_submit *io,
+ struct inode *inode,
+ struct writeback_control *wbc,
+ struct buffer_head *bh)
+{
+ struct ext4_io_page *new_io_page;
+ int ret;
+
+ if (buffer_new(bh)) {
+ clear_buffer_new(bh);
+ unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+ }
+
+ if (!buffer_mapped(bh)) {
+ clear_buffer_dirty(bh);
+ if (io->io_bio)
+ ext4_io_submit(io);
+ return 0;
+ }
+
+retry:
+ if (io->io_bio && bh->b_blocknr != io->io_next_block)
+ ext4_io_submit(io);
+ if (io->io_bio == NULL) {
+ ret = io_submit_init(io, inode, wbc, bh);
+ if (ret)
+ return ret;
+ }
+ if (buffer_uninit(bh))
+ io->io_end->flag |= EXT4_IO_END_UNWRITTEN;
+ io->io_end->size += bh->b_size;
+ io->io_next_block++;
+ ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
+ if (ret != bh->b_size) {
+ submit_and_retry:
+ ext4_io_submit(io);
+ goto retry;
+ }
+ if (!io->io_end->io_page || io->io_end->io_page->p_page != bh->b_page) {
+ new_io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
+ if (!new_io_page)
+ goto submit_and_retry;
+ get_page(bh->b_page);
+ new_io_page->p_page = bh->b_page;
+ new_io_page->p_next = io->io_end->io_page;
+ io->io_end->io_page = new_io_page;
+ }
+ return 0;
+}
+
+int ext4_bio_write_page(struct ext4_io_submit *io,
+ struct page *page,
+ int len,
+ struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ unsigned block_start, block_end, blocksize;
+ struct buffer_head *bh, *head;
+ int ret = 0, written = 0;
+
+ blocksize = 1 << inode->i_blkbits;
+
+ BUG_ON(PageWriteback(page));
+ set_page_writeback(page);
+ ClearPageError(page);
+
+ for (bh = head = page_buffers(page), block_start = 0;
+ bh != head || !block_start;
+ block_start=block_end, bh = bh->b_this_page) {
+ block_end = block_start + blocksize;
+ if (block_start >= len) {
+ clear_buffer_dirty(bh);
+ set_buffer_uptodate(bh);
+ continue;
+ }
+ ret = io_submit_add_bh(io, inode, wbc, bh);
+ if (ret) {
+ /*
+ * We only get here on ENOMEM. Not much else
+ * we can do but mark the page as dirty, and
+ * better luck next time.
+ */
+ set_page_dirty(page);
+ break;
+ }
+ written++;
+ }
+ unlock_page(page);
+ /*
+ * If the page was truncated before we could do the writeback,
+ * or we had a memory allocation error while trying to write
+ * the first buffer head, we won't have submitted any pages for
+ * I/O. In that case we need to make sure we've cleared the
+ * PageWriteback bit from the page to prevent the system from
+ * wedging later on.
+ */
+ if (written == 0)
+ end_page_writeback(page);
+ return ret;
+}
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 16002ec..9f602c2 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4768,9 +4768,12 @@ static int __init init_ext4_fs(void)
int err;
ext4_check_flag_values();
- err = init_ext4_system_zone();
+ err = init_ext4_pageio();
if (err)
return err;
+ err = init_ext4_system_zone();
+ if (err)
+ goto out5;
ext4_kset = kset_create_and_add("ext4", NULL, fs_kobj);
if (!ext4_kset)
goto out4;
@@ -4811,6 +4814,8 @@ out3:
kset_unregister(ext4_kset);
out4:
exit_ext4_system_zone();
+out5:
+ exit_ext4_pageio();
return err;
}
@@ -4826,6 +4831,7 @@ static void __exit exit_ext4_fs(void)
remove_proc_entry("fs/ext4", NULL);
kset_unregister(ext4_kset);
exit_ext4_system_zone();
+ exit_ext4_pageio();
}
MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
--
1.7.1
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