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Subjectdirect-to-BIO for O_DIRECT

Here's a patch which converts O_DIRECT to go direct-to-BIO, bypassing
the kiovec layer. It's followed by a patch which converts the raw
driver to use the O_DIRECT engine.

CPU utilisation is about the same as the kiovec-based implementation.
Read and write bandwidth are the same too, for 128k chunks. But with
one megabyte chunks, this implementation is 20% faster at writing.

I assume this is because the kiobuf-based implementation has to stop
and wait for each 128k chunk, whereas this code streams the entire
request, regardless of its size.

This is with a single (oldish) scsi disk on aic7xxx. I'd expect the
margin to widen on higher-end hardware which likes to have more
requests in flight.

Question is: what do we want to do with this sucker? These are the
remaining users of kiovecs:

drivers/md/lvm-snap.c
drivers/media/video/video-buf.c
drivers/mtd/devices/blkmtd.c
drivers/scsi/sg.c

the video and mtd drivers seems to be fairly easy to de-kiobufize.
I'm aware of one proprietary driver which uses kiobufs. XFS uses
kiobufs a little bit - just to map the pages.

So with a bit of effort and maintainer-irritation, we can extract
the kiobuf layer from the kernel.

Do we want to do that?



fs/Makefile | 2
fs/block_dev.c | 7
fs/buffer.c | 2
fs/direct-io.c | 491 ++++++++++++++++++++++++++++++++++++++++++++
fs/ext2/inode.c | 7
include/linux/buffer_head.h | 2
include/linux/fs.h | 11
mm/filemap.c | 64 ++---
8 files changed, 543 insertions(+), 43 deletions(-)

--- /dev/null Thu Aug 30 13:30:55 2001
+++ 2.5.25-akpm/fs/direct-io.c Sun Jul 7 19:40:20 2002
@@ -0,0 +1,491 @@
+/*
+ * mm/direct-io.c
+ *
+ * Copyright (C) 2002, Linus Torvalds.
+ *
+ * O_DIRECT
+ *
+ * 04Jul2002 akpm@zip.com.au
+ * Initial version
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/bio.h>
+#include <linux/wait.h>
+#include <linux/err.h>
+#include <linux/buffer_head.h>
+#include <linux/rwsem.h>
+#include <asm/atomic.h>
+
+/*
+ * The largest-sized BIO which this code will assemble, in bytes. Set this
+ * to PAGE_SIZE if your drivers are broken.
+ */
+#define DIO_BIO_MAX_SIZE BIO_MAX_SIZE
+
+/*
+ * How many user pages to map in one call to get_user_pages(). This determines
+ * the size of a structure on the stack.
+ */
+#define DIO_PAGES 64
+
+struct dio {
+ /* BIO submission state */
+ struct bio *bio; /* bio under assembly */
+ struct bio_vec *bvec; /* current bvec in that bio */
+ struct inode *inode;
+ int rw;
+ sector_t block_in_file; /* changes */
+ sector_t final_block_in_request;/* doesn't change */
+ unsigned first_block_in_page; /* doesn't change */
+ int boundary; /* prev block is at a boundary */
+ int reap_counter; /* rate limit reaping */
+ get_block_t *get_block;
+ sector_t last_block_in_bio;
+
+ /* Page fetching state */
+ int curr_page; /* changes */
+ int total_pages; /* doesn't change */
+ unsigned long curr_user_address;/* changes */
+
+ /* Page queue */
+ struct page *pages[DIO_PAGES];
+ unsigned head;
+ unsigned tail;
+
+ /* BIO completion state */
+ atomic_t bio_count;
+ spinlock_t bio_list_lock;
+ struct bio *bio_list; /* singly linked via bi_private */
+ wait_queue_head_t wait_q;
+};
+
+/*
+ * How many pages are in the queue?
+ */
+static inline unsigned dio_pages_present(struct dio *dio)
+{
+ return dio->head - dio->tail;
+}
+
+/*
+ * Go grab and pin some userspace pages. Typically we'll get 64 at a time.
+ */
+static int dio_refill_pages(struct dio *dio)
+{
+ int ret;
+ int nr_pages;
+
+ nr_pages = min(dio->total_pages - dio->curr_page, DIO_PAGES);
+ ret = get_user_pages(
+ current, /* Task for fault acounting */
+ current->mm, /* whose pages? */
+ dio->curr_user_address, /* Where from? */
+ nr_pages, /* How many pages? */
+ dio->rw == READ, /* Write to memory? */
+ 0, /* force (?) */
+ &dio->pages[0],
+ NULL); /* vmas */
+
+ if (ret >= 0) {
+ dio->curr_user_address += ret * PAGE_SIZE;
+ dio->curr_page += ret;
+ dio->head = 0;
+ dio->tail = ret;
+ ret = 0;
+ }
+ return ret;
+}
+
+/*
+ * Get another userspace page. Returns an ERR_PTR on error. Pages are
+ * buffered inside the dio so that we can call get_user_pages() against a
+ * decent number of pages, less frequently. To provide nicer use of the
+ * L1 cache.
+ */
+static struct page *dio_get_page(struct dio *dio)
+{
+ if (dio_pages_present(dio) == 0) {
+ int ret;
+
+ ret = dio_refill_pages(dio);
+ if (ret) {
+ printk("%s: dio_refill_pages returns %d\n",
+ __FUNCTION__, ret);
+ return ERR_PTR(ret);
+ }
+ BUG_ON(dio_pages_present(dio) == 0);
+ }
+ return dio->pages[dio->head++];
+}
+
+/*
+ * The BIO completion handler simply queues the BIO up for the process-context
+ * handler.
+ *
+ * During I/O bi_private points at the dio. After I/O, bi_private is used to
+ * implement a singly-linked list of completed BIOs, at dio->bio_list.
+ */
+static void dio_bio_end_io(struct bio *bio)
+{
+ struct dio *dio = bio->bi_private;
+ unsigned long flags;
+
+ spin_lock_irqsave(&dio->bio_list_lock, flags);
+ bio->bi_private = dio->bio_list;
+ dio->bio_list = bio;
+ spin_unlock_irqrestore(&dio->bio_list_lock, flags);
+ wake_up(&dio->wait_q);
+}
+
+static int
+dio_bio_alloc(struct dio *dio, struct block_device *bdev,
+ sector_t first_sector, int nr_vecs)
+{
+ struct bio *bio;
+
+ bio = bio_alloc(GFP_KERNEL, nr_vecs);
+ if (bio == NULL)
+ return -ENOMEM;
+
+ bio->bi_bdev = bdev;
+ bio->bi_vcnt = nr_vecs;
+ bio->bi_idx = 0;
+ bio->bi_size = 0;
+ bio->bi_sector = first_sector;
+ bio->bi_io_vec[0].bv_page = NULL;
+ bio->bi_end_io = dio_bio_end_io;
+
+ dio->bio = bio;
+ dio->bvec = NULL; /* debug */
+ return 0;
+}
+
+static void dio_bio_submit(struct dio *dio)
+{
+ struct bio *bio = dio->bio;
+
+ bio->bi_vcnt = bio->bi_idx;
+ bio->bi_idx = 0;
+ bio->bi_private = dio;
+ atomic_inc(&dio->bio_count);
+ submit_bio(dio->rw, bio);
+
+ dio->bio = NULL;
+ dio->bvec = NULL;
+}
+
+/*
+ * Release any resources in case of a failure
+ */
+static void dio_cleanup(struct dio *dio)
+{
+ while (dio_pages_present(dio))
+ page_cache_release(dio_get_page(dio));
+}
+
+/*
+ * Wait for the next BIO to complete. Remove it and return it.
+ */
+static struct bio *dio_await_one(struct dio *dio)
+{
+ DECLARE_WAITQUEUE(wait, current);
+ unsigned long flags;
+ struct bio *bio;
+
+ spin_lock_irqsave(&dio->bio_list_lock, flags);
+ while (dio->bio_list == NULL) {
+ add_wait_queue(&dio->wait_q, &wait);
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (dio->bio_list == NULL) {
+ spin_unlock_irqrestore(&dio->bio_list_lock, flags);
+ blk_run_queues();
+ schedule();
+ spin_lock_irqsave(&dio->bio_list_lock, flags);
+ }
+ set_current_state(TASK_RUNNING);
+ remove_wait_queue(&dio->wait_q, &wait);
+ }
+ bio = dio->bio_list;
+ dio->bio_list = bio->bi_private;
+ spin_unlock_irqrestore(&dio->bio_list_lock, flags);
+ return bio;
+}
+
+/*
+ * Process one completed BIO. No locks are held.
+ */
+static int dio_bio_complete(struct dio *dio, struct bio *bio)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct bio_vec *bvec = bio->bi_io_vec;
+ int page_no;
+ int ret = 0;
+
+ for (page_no = 0; page_no < bio->bi_vcnt; page_no++) {
+ struct page *page = bvec[page_no].bv_page;
+
+ if (!uptodate) {
+ if (ret == 0)
+ ret = -EIO;
+ }
+
+ if (dio->rw == READ)
+ set_page_dirty(page);
+ page_cache_release(page);
+ }
+ atomic_dec(&dio->bio_count);
+ bio_put(bio);
+ return ret;
+}
+
+/*
+ * Wait on and process all in-flight BIOs.
+ */
+static int dio_await_completion(struct dio *dio)
+{
+ int ret = 0;
+ while (atomic_read(&dio->bio_count)) {
+ struct bio *bio = dio_await_one(dio);
+ int ret2;
+
+ ret2 = dio_bio_complete(dio, bio);
+ if (ret == 0)
+ ret = ret2;
+ }
+ return ret;
+}
+
+/*
+ * A really large O_DIRECT read or write can generate a lot of BIOs. So
+ * to keep the memory consumption sane we periodically reap any completed BIOs
+ * during the BIO generation phase.
+ *
+ * This also helps to limis the peak amount of pinned userspace memory.
+ */
+static int dio_bio_reap(struct dio *dio)
+{
+ int ret = 0;
+
+ if (dio->reap_counter++ >= 64) {
+ while (dio->bio_list) {
+ unsigned long flags;
+ struct bio *bio;
+ int ret2;
+
+ spin_lock_irqsave(&dio->bio_list_lock, flags);
+ bio = dio->bio_list;
+ dio->bio_list = bio->bi_private;
+ spin_unlock_irqrestore(&dio->bio_list_lock, flags);
+ ret2 = dio_bio_complete(dio, bio);
+ if (ret == 0)
+ ret = ret2;
+ }
+ dio->reap_counter = 0;
+ }
+ return ret;
+}
+
+/*
+ * Walk the user pages, and the file, mapping blocks to disk and emitting BIOs.
+ */
+int do_direct_IO(struct dio *dio)
+{
+ struct inode * const inode = dio->inode;
+ const unsigned blkbits = inode->i_blkbits;
+ const unsigned blocksize = 1 << blkbits;
+ const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
+ struct page *page;
+ unsigned block_in_page;
+ int ret;
+
+ /* The I/O can start at any block offset within the first page */
+ block_in_page = dio->first_block_in_page;
+
+ while (dio->block_in_file < dio->final_block_in_request) {
+ int new_page; /* Need to insert this page into the BIO? */
+
+ page = dio_get_page(dio);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto out;
+ }
+
+ new_page = 1;
+ for ( ; block_in_page < blocks_per_page; block_in_page++) {
+ struct buffer_head map_bh;
+ struct bio *bio;
+
+ map_bh.b_state = 0;
+ ret = (*dio->get_block)(inode, dio->block_in_file,
+ &map_bh, dio->rw == WRITE);
+ if (ret) {
+ printk("%s: get_block returns %d\n",
+ __FUNCTION__, ret);
+ goto fail_release;
+ }
+ /* blockdevs do not set buffer_new */
+ if (buffer_new(&map_bh))
+ unmap_underlying_metadata(map_bh.b_bdev,
+ map_bh.b_blocknr);
+ if (!buffer_mapped(&map_bh)) {
+ ret = -EINVAL; /* A hole */
+ goto fail_release;
+ }
+ if (dio->bio) {
+ if (dio->bio->bi_idx == dio->bio->bi_vcnt ||
+ dio->boundary ||
+ dio->last_block_in_bio !=
+ map_bh.b_blocknr - 1) {
+ dio_bio_submit(dio);
+ dio->boundary = 0;
+ }
+ }
+ if (dio->bio == NULL) {
+ ret = dio_bio_reap(dio);
+ if (ret)
+ goto fail_release;
+ ret = dio_bio_alloc(dio, map_bh.b_bdev,
+ map_bh.b_blocknr << (blkbits - 9),
+ DIO_BIO_MAX_SIZE / PAGE_SIZE);
+ if (ret)
+ goto fail_release;
+ new_page = 1;
+ dio->boundary = 0;
+ }
+
+ bio = dio->bio;
+ if (new_page) {
+ dio->bvec = &bio->bi_io_vec[bio->bi_idx];
+ page_cache_get(page);
+ dio->bvec->bv_page = page;
+ dio->bvec->bv_len = 0;
+ dio->bvec->bv_offset = block_in_page*blocksize;
+ bio->bi_idx++;
+ }
+ new_page = 0;
+ dio->bvec->bv_len += blocksize;
+ bio->bi_size += blocksize;
+ dio->last_block_in_bio = map_bh.b_blocknr;
+ dio->boundary = buffer_boundary(&map_bh);
+
+ dio->block_in_file++;
+ if (dio->block_in_file >= dio->final_block_in_request)
+ break;
+ }
+ block_in_page = 0;
+ page_cache_release(page);
+ }
+ ret = 0;
+ goto out;
+fail_release:
+ page_cache_release(page);
+out:
+ return ret;
+}
+
+struct dio *g_dio;
+
+int
+generic_direct_IO(int rw, struct inode *inode, char *buf, loff_t offset,
+ size_t count, get_block_t get_block)
+{
+ const unsigned blocksize_mask = (1 << inode->i_blkbits) - 1;
+ const unsigned long user_addr = (unsigned long)buf;
+ int ret = 0;
+ int ret2;
+ struct dio dio;
+ size_t bytes;
+
+ /* Check the memory alignment. Blocks cannot straddle pages */
+ if ((user_addr & blocksize_mask) || (count & blocksize_mask)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ g_dio = &dio;
+
+ /* BIO submission state */
+ dio.bio = NULL;
+ dio.bvec = NULL;
+ dio.inode = inode;
+ dio.rw = rw;
+ dio.block_in_file = offset >> inode->i_blkbits;
+ dio.final_block_in_request = (offset + count) >> inode->i_blkbits;
+
+ /* Index into the first page of the first block */
+ dio.first_block_in_page = (user_addr & (PAGE_SIZE - 1))
+ >> inode->i_blkbits;
+ dio.boundary = 0;
+ dio.reap_counter = 0;
+ dio.get_block = get_block;
+ dio.last_block_in_bio = -1;
+
+ /* Page fetching state */
+ dio.curr_page = 0;
+ bytes = count;
+ dio.total_pages = 0;
+ if (offset & PAGE_SIZE) {
+ dio.total_pages++;
+ bytes -= PAGE_SIZE - (offset & ~(PAGE_SIZE - 1));
+ }
+ dio.total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
+ dio.curr_user_address = user_addr;
+
+ /* Page queue */
+ dio.head = 0;
+ dio.tail = 0;
+
+ /* BIO completion state */
+ atomic_set(&dio.bio_count, 0);
+ spin_lock_init(&dio.bio_list_lock);
+ dio.bio_list = NULL;
+ init_waitqueue_head(&dio.wait_q);
+
+ down_read(&current->mm->mmap_sem);
+ ret = do_direct_IO(&dio);
+ up_read(&current->mm->mmap_sem);
+
+ if (dio.bio)
+ dio_bio_submit(&dio);
+ if (ret)
+ dio_cleanup(&dio);
+ ret2 = dio_await_completion(&dio);
+ if (ret == 0)
+ ret = ret2;
+ if (ret == 0)
+ ret = count - ((dio.final_block_in_request -
+ dio.block_in_file) << inode->i_blkbits);
+out:
+ return ret;
+}
+
+ssize_t
+generic_file_direct_IO(int rw, struct inode *inode, char *buf,
+ loff_t offset, size_t count)
+{
+ struct address_space *mapping = inode->i_mapping;
+ unsigned blocksize_mask;
+ ssize_t retval;
+
+ blocksize_mask = (1 << inode->i_blkbits) - 1;
+ if ((offset & blocksize_mask) || (count & blocksize_mask)) {
+ retval = -EINVAL;
+ goto out;
+ }
+
+ if (mapping->nrpages) {
+ retval = filemap_fdatawrite(mapping);
+ if (retval == 0)
+ retval = filemap_fdatawait(mapping);
+ if (retval)
+ goto out;
+ }
+ retval = mapping->a_ops->direct_IO(rw, inode, buf, offset, count);
+out:
+ return retval;
+}
--- 2.5.25/include/linux/fs.h~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/include/linux/fs.h Sun Jul 7 19:35:39 2002
@@ -303,8 +303,8 @@ struct address_space_operations {
int (*bmap)(struct address_space *, long);
int (*invalidatepage) (struct page *, unsigned long);
int (*releasepage) (struct page *, int);
-#define KERNEL_HAS_O_DIRECT /* this is for modules out of the kernel */
- int (*direct_IO)(int, struct inode *, struct kiobuf *, unsigned long, int);
+ int (*direct_IO)(int, struct inode *, char *buf,
+ loff_t offset, size_t count);
};

struct backing_dev_info;
@@ -1128,7 +1128,7 @@ extern int check_disk_change(kdev_t);
extern int invalidate_inodes(struct super_block *);
extern int invalidate_device(kdev_t, int);
extern void invalidate_inode_pages(struct inode *);
-extern void invalidate_inode_pages2(struct address_space *);
+extern void invalidate_inode_pages2(struct address_space *mapping);
extern void write_inode_now(struct inode *, int);
extern int filemap_fdatawrite(struct address_space *);
extern int filemap_fdatawait(struct address_space *);
@@ -1233,6 +1233,11 @@ extern int file_read_actor(read_descript
extern ssize_t generic_file_read(struct file *, char *, size_t, loff_t *);
extern ssize_t generic_file_write(struct file *, const char *, size_t, loff_t *);
extern void do_generic_file_read(struct file *, loff_t *, read_descriptor_t *, read_actor_t);
+ssize_t generic_file_direct_IO(int rw, struct inode *inode, char *buf,
+ loff_t offset, size_t count);
+int generic_direct_IO(int rw, struct inode *inode, char *buf,
+ loff_t offset, size_t count, get_block_t *get_block);
+
extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
extern loff_t remote_llseek(struct file *file, loff_t offset, int origin);
--- 2.5.25/include/linux/buffer_head.h~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/include/linux/buffer_head.h Sun Jul 7 19:35:39 2002
@@ -182,8 +182,6 @@ int block_sync_page(struct page *);
sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
int block_truncate_page(struct address_space *, loff_t, get_block_t *);
-int generic_direct_IO(int, struct inode *, struct kiobuf *,
- unsigned long, int, get_block_t *);
int file_fsync(struct file *, struct dentry *, int);

#define OSYNC_METADATA (1<<0)
--- 2.5.25/fs/buffer.c~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/fs/buffer.c Sun Jul 7 19:35:39 2002
@@ -2298,6 +2298,7 @@ sector_t generic_block_bmap(struct addre
return tmp.b_blocknr;
}

+#if 0
int generic_direct_IO(int rw, struct inode *inode,
struct kiobuf *iobuf, unsigned long blocknr,
int blocksize, get_block_t *get_block)
@@ -2344,6 +2345,7 @@ int generic_direct_IO(int rw, struct ino
out:
return retval;
}
+#endif

/*
* Start I/O on a physical range of kernel memory, defined by a vector
--- 2.5.25/mm/filemap.c~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/mm/filemap.c Sun Jul 7 19:35:39 2002
@@ -413,7 +413,7 @@ static int invalidate_list_pages2(struct
* free the pages because they're mapped.
* @mapping: the address_space which pages we want to invalidate
*/
-void invalidate_inode_pages2(struct address_space * mapping)
+void invalidate_inode_pages2(struct address_space *mapping)
{
int unlocked;

@@ -1101,6 +1101,7 @@ no_cached_page:
UPDATE_ATIME(inode);
}

+#if 0
static ssize_t generic_file_direct_IO(int rw, struct file * filp, char * buf, size_t count, loff_t offset)
{
ssize_t retval;
@@ -1181,6 +1182,7 @@ static ssize_t generic_file_direct_IO(in
out:
return retval;
}
+#endif

int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
{
@@ -1208,15 +1210,36 @@ int file_read_actor(read_descriptor_t *
* This is the "read()" routine for all filesystems
* that can use the page cache directly.
*/
-ssize_t generic_file_read(struct file * filp, char * buf, size_t count, loff_t *ppos)
+ssize_t
+generic_file_read(struct file *filp, char *buf, size_t count, loff_t *ppos)
{
ssize_t retval;

if ((ssize_t) count < 0)
return -EINVAL;

- if (filp->f_flags & O_DIRECT)
- goto o_direct;
+ if (filp->f_flags & O_DIRECT) {
+ loff_t pos = *ppos, size;
+ struct address_space *mapping;
+ struct inode *inode;
+
+ mapping = filp->f_dentry->d_inode->i_mapping;
+ inode = mapping->host;
+ retval = 0;
+ if (!count)
+ goto out; /* skip atime */
+ size = inode->i_size;
+ if (pos < size) {
+ if (pos + count > size)
+ count = size - pos;
+ retval = generic_file_direct_IO(READ, inode,
+ buf, pos, count);
+ if (retval > 0)
+ *ppos = pos + retval;
+ }
+ UPDATE_ATIME(filp->f_dentry->d_inode);
+ goto out;
+ }

retval = -EFAULT;
if (access_ok(VERIFY_WRITE, buf, count)) {
@@ -1229,36 +1252,14 @@ ssize_t generic_file_read(struct file *
desc.count = count;
desc.buf = buf;
desc.error = 0;
- do_generic_file_read(filp, ppos, &desc, file_read_actor);
-
+ do_generic_file_read(filp,ppos,&desc,file_read_actor);
retval = desc.written;
if (!retval)
retval = desc.error;
}
}
- out:
+out:
return retval;
-
- o_direct:
- {
- loff_t pos = *ppos, size;
- struct address_space *mapping = filp->f_dentry->d_inode->i_mapping;
- struct inode *inode = mapping->host;
-
- retval = 0;
- if (!count)
- goto out; /* skip atime */
- size = inode->i_size;
- if (pos < size) {
- if (pos + count > size)
- count = size - pos;
- retval = generic_file_direct_IO(READ, filp, buf, count, pos);
- if (retval > 0)
- *ppos = pos + retval;
- }
- UPDATE_ATIME(filp->f_dentry->d_inode);
- goto out;
- }
}

static int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset , unsigned long size)
@@ -2199,8 +2200,8 @@ generic_file_write(struct file *file, co
}

if (unlikely(file->f_flags & O_DIRECT)) {
- written = generic_file_direct_IO(WRITE, file,
- (char *) buf, count, pos);
+ written = generic_file_direct_IO(WRITE, inode,
+ (char *)buf, pos, count);
if (written > 0) {
loff_t end = pos + written;
if (end > inode->i_size && !S_ISBLK(inode->i_mode)) {
@@ -2208,7 +2209,8 @@ generic_file_write(struct file *file, co
mark_inode_dirty(inode);
}
*ppos = end;
- invalidate_inode_pages2(mapping);
+ if (mapping->nrpages)
+ invalidate_inode_pages2(mapping);
}
/*
* Sync the fs metadata but not the minor inode changes and
--- 2.5.25/fs/ext2/inode.c~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/fs/ext2/inode.c Sun Jul 7 19:35:39 2002
@@ -607,11 +607,10 @@ static int ext2_bmap(struct address_spac
}

static int
-ext2_direct_IO(int rw, struct inode *inode, struct kiobuf *iobuf,
- unsigned long blocknr, int blocksize)
+ext2_direct_IO(int rw, struct inode *inode, char *buf,
+ loff_t offset, size_t count)
{
- return generic_direct_IO(rw, inode, iobuf, blocknr,
- blocksize, ext2_get_block);
+ return generic_direct_IO(rw, inode, buf, offset, count, ext2_get_block);
}

static int
--- 2.5.25/fs/Makefile~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/fs/Makefile Sun Jul 7 19:35:39 2002
@@ -15,7 +15,7 @@ obj-y := open.o read_write.o devices.o f
namei.o fcntl.o ioctl.o readdir.o select.o fifo.o locks.o \
dcache.o inode.o attr.o bad_inode.o file.o iobuf.o dnotify.o \
filesystems.o namespace.o seq_file.o xattr.o libfs.o \
- fs-writeback.o mpage.o
+ fs-writeback.o mpage.o direct-io.o

ifneq ($(CONFIG_NFSD),n)
ifneq ($(CONFIG_NFSD),)
--- 2.5.25/fs/block_dev.c~odirect-redux Sun Jul 7 19:35:39 2002
+++ 2.5.25-akpm/fs/block_dev.c Sun Jul 7 19:35:39 2002
@@ -105,9 +105,12 @@ static int blkdev_get_block(struct inode
return 0;
}

-static int blkdev_direct_IO(int rw, struct inode * inode, struct kiobuf * iobuf, unsigned long blocknr, int blocksize)
+static int
+blkdev_direct_IO(int rw, struct inode *inode, char *buf,
+ loff_t offset, size_t count)
{
- return generic_direct_IO(rw, inode, iobuf, blocknr, blocksize, blkdev_get_block);
+ return generic_direct_IO(rw, inode, buf, offset,
+ count, blkdev_get_block);
}

static int blkdev_writepage(struct page * page)
-


raw.c | 136 ++++++++++++------------------------------------------------------
1 files changed, 26 insertions(+), 110 deletions(-)
--- 2.5.25/drivers/char/raw.c~raw-use-generic Sun Jul 7 19:35:44 2002
+++ 2.5.25-akpm/drivers/char/raw.c Sun Jul 7 19:58:33 2002
@@ -8,8 +8,8 @@
* device are used to bind the other minor numbers to block devices.
*/

+#include <linux/init.h>
#include <linux/fs.h>
-#include <linux/iobuf.h>
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/raw.h>
@@ -86,12 +86,6 @@ int raw_open(struct inode *inode, struct
return 0;
}

- if (!filp->f_iobuf) {
- err = alloc_kiovec(1, &filp->f_iobuf);
- if (err)
- return err;
- }
-
down(&raw_devices[minor].mutex);
/*
* No, it is a normal raw device. All we need to do on open is
@@ -256,124 +250,46 @@ int raw_ctl_ioctl(struct inode *inode,
return err;
}

-
-
-ssize_t raw_read(struct file *filp, char * buf,
- size_t size, loff_t *offp)
+ssize_t raw_read(struct file *filp, char * buf, size_t size, loff_t *offp)
{
return rw_raw_dev(READ, filp, buf, size, offp);
}

-ssize_t raw_write(struct file *filp, const char *buf,
- size_t size, loff_t *offp)
+ssize_t raw_write(struct file *filp, const char *buf, size_t size, loff_t *offp)
{
return rw_raw_dev(WRITE, filp, (char *) buf, size, offp);
}

-#define SECTOR_BITS 9
-#define SECTOR_SIZE (1U << SECTOR_BITS)
-#define SECTOR_MASK (SECTOR_SIZE - 1)
-
-ssize_t rw_raw_dev(int rw, struct file *filp, char *buf,
- size_t size, loff_t *offp)
+ssize_t
+rw_raw_dev(int rw, struct file *filp, char *buf, size_t size, loff_t *offp)
{
- struct kiobuf * iobuf;
- int new_iobuf;
- int err = 0;
- unsigned long blocks;
- size_t transferred;
- int iosize;
- int minor;
- kdev_t dev;
- unsigned long limit;
- int sector_size, sector_bits, sector_mask;
- sector_t blocknr;
struct block_device *bdev;
-
- /*
- * First, a few checks on device size limits
- */
+ struct inode *inode;
+ int minor;
+ ssize_t ret = 0;

minor = minor(filp->f_dentry->d_inode->i_rdev);
-
- new_iobuf = 0;
- iobuf = filp->f_iobuf;
- if (test_and_set_bit(0, &filp->f_iobuf_lock)) {
- /*
- * A parallel read/write is using the preallocated iobuf
- * so just run slow and allocate a new one.
- */
- err = alloc_kiovec(1, &iobuf);
- if (err)
- goto out;
- new_iobuf = 1;
- }
-
bdev = raw_devices[minor].binding;
- dev = to_kdev_t(bdev->bd_dev);
- sector_size = raw_devices[minor].sector_size;
- sector_bits = raw_devices[minor].sector_bits;
- sector_mask = sector_size - 1;
-
- limit = bdev->bd_inode->i_size >> sector_bits;
- if (!limit)
- limit = INT_MAX;
- dprintk ("rw_raw_dev: dev %d:%d (+%d)\n",
- major(dev), minor(dev), limit);
-
- err = -EINVAL;
- if ((*offp & sector_mask) || (size & sector_mask))
- goto out_free;
- err = 0;
- if (size)
- err = -ENXIO;
- if ((*offp >> sector_bits) >= limit)
- goto out_free;
-
- transferred = 0;
- blocknr = *offp >> sector_bits;
- while (size > 0) {
- blocks = size >> sector_bits;
- if (blocks > limit - blocknr)
- blocks = limit - blocknr;
- if (!blocks)
- break;
-
- iosize = blocks << sector_bits;
+ inode = bdev->bd_inode;

- err = map_user_kiobuf(rw, iobuf, (unsigned long) buf, iosize);
- if (err)
- break;
-
- err = brw_kiovec(rw, 1, &iobuf, raw_devices[minor].binding, &blocknr, sector_size);
-
- if (rw == READ && err > 0)
- mark_dirty_kiobuf(iobuf, err);
-
- if (err >= 0) {
- transferred += err;
- size -= err;
- buf += err;
- }
-
- blocknr += blocks;
-
- unmap_kiobuf(iobuf);
-
- if (err != iosize)
- break;
+ if (size == 0)
+ goto out;
+ if (size < 0) {
+ ret = -EINVAL;
+ goto out;
}
-
- if (transferred) {
- *offp += transferred;
- err = transferred;
+ if (*offp >= inode->i_size) {
+ ret = -ENXIO;
+ goto out;
}
+ if (size + *offp > inode->i_size)
+ size = inode->i_size - *offp;

- out_free:
- if (!new_iobuf)
- clear_bit(0, &filp->f_iobuf_lock);
- else
- free_kiovec(1, &iobuf);
- out:
- return err;
+ ret = generic_file_direct_IO(rw, inode, buf, *offp, size);
+ if (ret > 0)
+ *offp += ret;
+ if (inode->i_mapping->nrpages)
+ invalidate_inode_pages2(inode->i_mapping);
+out:
+ return ret;
}
-
-
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