Re: [patch] optimize o_direct on block device - v2
On Mon, 4 Dec 2006 20:55:50 -0800 "Chen, Kenneth W" <[EMAIL PROTECTED]> wrote: > This patch implements block device specific .direct_IO method instead > of going through generic direct_io_worker for block device. > > direct_io_worker is fairly complex because it needs to handle O_DIRECT > on file system, where it needs to perform block allocation, hole detection, > extents file on write, and tons of other corner cases. The end result is > that it takes tons of CPU time to submit an I/O. > > For block device, the block allocation is much simpler and a tight triple > loop can be written to iterate each iovec and each page within the iovec > in order to construct/prepare bio structure and then subsequently submit > it to the block layer. This significantly speeds up O_D on block device. > Looks reasonable to me. A few musings: > > -static int > -blkdev_get_blocks(struct inode *inode, sector_t iblock, > - struct buffer_head *bh, int create) > +int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) > { > - sector_t end_block = max_block(I_BDEV(inode)); > - unsigned long max_blocks = bh->b_size >> inode->i_blkbits; > + struct kiocb* iocb = bio->bi_private; > + atomic_t* bio_count = (atomic_t*) >private; This atomic_t-in-a-void* thing is rather unpleasing. It could be a new member of `struct kiocb', perhaps. Please use " *" rather than "* ". > + long res; > + > + if ((bio->bi_rw & 1) == READ) bio_data_dir() > + bio_check_pages_dirty(bio); > + else { > + bio_release_pages(bio); > + bio_put(bio); > + } > > - if ((iblock + max_blocks) > end_block) { > - max_blocks = end_block - iblock; > - if ((long)max_blocks <= 0) { > - if (create) > - return -EIO;/* write fully beyond EOF */ > - /* > - * It is a read which is fully beyond EOF. We return > - * a !buffer_mapped buffer > - */ > - max_blocks = 0; > - } > + if (error) > + iocb->ki_left = -EIO; > + > + if (atomic_dec_and_test(bio_count)) { > + res = (iocb->ki_left < 0) ? iocb->ki_left : iocb->ki_nbytes; > + aio_complete(iocb, res, 0); > } > > - bh->b_bdev = I_BDEV(inode); > - bh->b_blocknr = iblock; > - bh->b_size = max_blocks << inode->i_blkbits; > - if (max_blocks) > - set_buffer_mapped(bh); > return 0; > } > > +#define VEC_SIZE 16 > +struct pvec { > + unsigned short nr; > + unsigned short idx; > + struct page *page[VEC_SIZE]; > +}; Do we actually need this? afaict all it does is saves an additional function arg in a couple of places. I guess it doesn't hurt though. > + > +struct page *blk_get_page(unsigned long addr, size_t count, int rw, > + struct pvec *pvec) Does this need kernel-wide scope? A nice introductory comment explaining what it does would be, err, nice. > +{ > + int ret, nr_pages; > + if (pvec->idx == pvec->nr) { > + nr_pages = (addr + count + PAGE_SIZE - 1) / PAGE_SIZE - > + addr / PAGE_SIZE; > + nr_pages = min(nr_pages, VEC_SIZE); > + down_read(>mm->mmap_sem); > + ret = get_user_pages(current, current->mm, addr, nr_pages, > + rw==READ, 0, pvec->page, NULL); > + up_read(>mm->mmap_sem); > + if (ret < 0) > + return ERR_PTR(ret); > + pvec->nr = ret; > + pvec->idx = 0; > + } > + return pvec->page[pvec->idx++]; > +} hm, if get_user_pages() returns zero, badness ensues. It won't do that, unless perhaps we passed it a zero nr_pages in the first place. We shouldn't do that. Has this code been tested with zero-length writes? And with iovecs which contain a zero-length segment? > static ssize_t > blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, > - loff_t offset, unsigned long nr_segs) > + loff_t pos, unsigned long nr_segs) > { > - struct file *file = iocb->ki_filp; > - struct inode *inode = file->f_mapping->host; > + struct inode *inode = iocb->ki_filp->f_mapping->host; > + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); > + unsigned blocksize_mask = (1<< blkbits) - 1; > + unsigned long seg, nvec, cur_off, cur_len; > + > + unsigned long addr; > + size_t count, nbytes = iocb->ki_nbytes; > + loff_t size; > + struct bio * bio; > + atomic_t *bio_count = (atomic_t *) >private; > + struct page *page; > + struct pvec pvec = {.nr = 0, .idx = 0, }; Please use one declaration per line (no commas). That leaves you room for a little comment alongside each local, explaining its operation. This function needs little
Re: [patch] optimize o_direct on block device - v2
On Tue, 5 Dec 2006 11:02:30 + Christoph Hellwig <[EMAIL PROTECTED]> wrote: > > + long res; > > + > > + if ((bio->bi_rw & 1) == READ) > > I just wanted to complain about not using a proper helper for this, > but apparently we don't have one yet.. There's bio_data_dir(). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [patch] optimize o_direct on block device - v2
On Mon, Dec 04, 2006 at 08:55:50PM -0800, Chen, Kenneth W wrote: > This patch implements block device specific .direct_IO method instead > of going through generic direct_io_worker for block device. > > direct_io_worker is fairly complex because it needs to handle O_DIRECT > on file system, where it needs to perform block allocation, hole detection, > extents file on write, and tons of other corner cases. The end result is > that it takes tons of CPU time to submit an I/O. > > For block device, the block allocation is much simpler and a tight triple > loop can be written to iterate each iovec and each page within the iovec > in order to construct/prepare bio structure and then subsequently submit > it to the block layer. This significantly speeds up O_D on block device. I think this separation makes a lot of sense. direct-io.c has to deal with a lot of convuled issues that only arise on regular files, and the block mapping is the most trivial part of that :) While you're at it please send a followup patch that removes the DIO_NO_LOCKING code from direct-io.c as it's now unused and only needlessly complicates the code. (Hopefully we'll get down to one single variant one day..) > --- ./fs/block_dev.c.orig 2006-11-29 13:57:37.0 -0800 > +++ ./fs/block_dev.c 2006-12-04 18:38:53.0 -0800 > @@ -129,43 +129,164 @@ blkdev_get_block(struct inode *inode, se > return 0; > } > > -static int > -blkdev_get_blocks(struct inode *inode, sector_t iblock, > - struct buffer_head *bh, int create) > +int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) This should be static. > + struct kiocb* iocb = bio->bi_private; > + atomic_t* bio_count = (atomic_t*) >private; The * placement is wrong all over. This should be: struct kiocb *iocb = bio->bi_private; atomic_t *bio_count = (atomic_t *)>private; > + long res; > + > + if ((bio->bi_rw & 1) == READ) I just wanted to complain about not using a proper helper for this, but apparently we don't have one yet.. > + bio_check_pages_dirty(bio); > + else { > + bio_release_pages(bio); > + bio_put(bio); > + } > + if (error) > + iocb->ki_left = -EIO; > + > + if (atomic_dec_and_test(bio_count)) { > + res = (iocb->ki_left < 0) ? iocb->ki_left : iocb->ki_nbytes; > + aio_complete(iocb, res, 0); > } I suspect this would be a lot more readable as: if (atomic_dec_and_test(bio_count)) { if (iocb->ki_left < 0) aio_complete(iocb, iocb->ki_left, 0); else aio_complete(iocb, iocb->ki_nbytes, 0); } > +struct page *blk_get_page(unsigned long addr, size_t count, int rw, > + struct pvec *pvec) static, again. > +{ > + int ret, nr_pages; > + if (pvec->idx == pvec->nr) { > + nr_pages = (addr + count + PAGE_SIZE - 1) / PAGE_SIZE - > + addr / PAGE_SIZE; > + nr_pages = min(nr_pages, VEC_SIZE); Didn't someone say you should add a macro for this in the last round of reviews? > + down_read(>mm->mmap_sem); > + ret = get_user_pages(current, current->mm, addr, nr_pages, > + rw==READ, 0, pvec->page, NULL); rw == READ > static ssize_t > blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, > - loff_t offset, unsigned long nr_segs) > + loff_t pos, unsigned long nr_segs) > { > - struct file *file = iocb->ki_filp; > - struct inode *inode = file->f_mapping->host; > + struct inode *inode = iocb->ki_filp->f_mapping->host; > + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); > + unsigned blocksize_mask = (1<< blkbits) - 1; > + unsigned long seg, nvec, cur_off, cur_len; > + > + unsigned long addr; > + size_t count, nbytes = iocb->ki_nbytes; > + loff_t size; > + struct bio * bio; > + atomic_t *bio_count = (atomic_t *) >private; > + struct page *page; > + struct pvec pvec = {.nr = 0, .idx = 0, }; > + > + BUILD_BUG_ON(sizeof(atomic_t) > sizeof(iocb->private)); > + > + size = i_size_read(inode); > + if (pos + nbytes > size) > + nbytes = size - pos; > + > + seg = 0; > + addr = (unsigned long) iov[0].iov_base; > + count = iov[0].iov_len; > + atomic_set(bio_count, 1); > + > + /* first check the alignment */ > + if (addr & blocksize_mask || count & blocksize_mask || > + pos & blocksize_mask) > + return -EINVAL; You only use one iovec and simply ignore all others, that's a huge regression over the existing functionality (and actually a bug that causes silent data loss) > static int blkdev_writepage(struct page *page, struct writeback_control *wbc) > --- ./fs/read_write.c.orig
Re: [patch] optimize o_direct on block device - v2
On Mon, 4 Dec 2006 20:55:50 -0800 Chen, Kenneth W [EMAIL PROTECTED] wrote: This patch implements block device specific .direct_IO method instead of going through generic direct_io_worker for block device. direct_io_worker is fairly complex because it needs to handle O_DIRECT on file system, where it needs to perform block allocation, hole detection, extents file on write, and tons of other corner cases. The end result is that it takes tons of CPU time to submit an I/O. For block device, the block allocation is much simpler and a tight triple loop can be written to iterate each iovec and each page within the iovec in order to construct/prepare bio structure and then subsequently submit it to the block layer. This significantly speeds up O_D on block device. Looks reasonable to me. A few musings: -static int -blkdev_get_blocks(struct inode *inode, sector_t iblock, - struct buffer_head *bh, int create) +int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) { - sector_t end_block = max_block(I_BDEV(inode)); - unsigned long max_blocks = bh-b_size inode-i_blkbits; + struct kiocb* iocb = bio-bi_private; + atomic_t* bio_count = (atomic_t*) iocb-private; This atomic_t-in-a-void* thing is rather unpleasing. It could be a new member of `struct kiocb', perhaps. Please use * rather than * . + long res; + + if ((bio-bi_rw 1) == READ) bio_data_dir() + bio_check_pages_dirty(bio); + else { + bio_release_pages(bio); + bio_put(bio); + } - if ((iblock + max_blocks) end_block) { - max_blocks = end_block - iblock; - if ((long)max_blocks = 0) { - if (create) - return -EIO;/* write fully beyond EOF */ - /* - * It is a read which is fully beyond EOF. We return - * a !buffer_mapped buffer - */ - max_blocks = 0; - } + if (error) + iocb-ki_left = -EIO; + + if (atomic_dec_and_test(bio_count)) { + res = (iocb-ki_left 0) ? iocb-ki_left : iocb-ki_nbytes; + aio_complete(iocb, res, 0); } - bh-b_bdev = I_BDEV(inode); - bh-b_blocknr = iblock; - bh-b_size = max_blocks inode-i_blkbits; - if (max_blocks) - set_buffer_mapped(bh); return 0; } +#define VEC_SIZE 16 +struct pvec { + unsigned short nr; + unsigned short idx; + struct page *page[VEC_SIZE]; +}; Do we actually need this? afaict all it does is saves an additional function arg in a couple of places. I guess it doesn't hurt though. + +struct page *blk_get_page(unsigned long addr, size_t count, int rw, + struct pvec *pvec) Does this need kernel-wide scope? A nice introductory comment explaining what it does would be, err, nice. +{ + int ret, nr_pages; + if (pvec-idx == pvec-nr) { + nr_pages = (addr + count + PAGE_SIZE - 1) / PAGE_SIZE - + addr / PAGE_SIZE; + nr_pages = min(nr_pages, VEC_SIZE); + down_read(current-mm-mmap_sem); + ret = get_user_pages(current, current-mm, addr, nr_pages, + rw==READ, 0, pvec-page, NULL); + up_read(current-mm-mmap_sem); + if (ret 0) + return ERR_PTR(ret); + pvec-nr = ret; + pvec-idx = 0; + } + return pvec-page[pvec-idx++]; +} hm, if get_user_pages() returns zero, badness ensues. It won't do that, unless perhaps we passed it a zero nr_pages in the first place. We shouldn't do that. Has this code been tested with zero-length writes? And with iovecs which contain a zero-length segment? static ssize_t blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs) + loff_t pos, unsigned long nr_segs) { - struct file *file = iocb-ki_filp; - struct inode *inode = file-f_mapping-host; + struct inode *inode = iocb-ki_filp-f_mapping-host; + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); + unsigned blocksize_mask = (1 blkbits) - 1; + unsigned long seg, nvec, cur_off, cur_len; + + unsigned long addr; + size_t count, nbytes = iocb-ki_nbytes; + loff_t size; + struct bio * bio; + atomic_t *bio_count = (atomic_t *) iocb-private; + struct page *page; + struct pvec pvec = {.nr = 0, .idx = 0, }; Please use one declaration per line (no commas). That leaves you room for a little comment alongside each local, explaining its operation. This function needs little comments alongside each local, explaining their operation. + BUILD_BUG_ON(sizeof(atomic_t) sizeof(iocb-private)); argh.
Re: [patch] optimize o_direct on block device - v2
On Mon, Dec 04, 2006 at 08:55:50PM -0800, Chen, Kenneth W wrote: This patch implements block device specific .direct_IO method instead of going through generic direct_io_worker for block device. direct_io_worker is fairly complex because it needs to handle O_DIRECT on file system, where it needs to perform block allocation, hole detection, extents file on write, and tons of other corner cases. The end result is that it takes tons of CPU time to submit an I/O. For block device, the block allocation is much simpler and a tight triple loop can be written to iterate each iovec and each page within the iovec in order to construct/prepare bio structure and then subsequently submit it to the block layer. This significantly speeds up O_D on block device. I think this separation makes a lot of sense. direct-io.c has to deal with a lot of convuled issues that only arise on regular files, and the block mapping is the most trivial part of that :) While you're at it please send a followup patch that removes the DIO_NO_LOCKING code from direct-io.c as it's now unused and only needlessly complicates the code. (Hopefully we'll get down to one single variant one day..) --- ./fs/block_dev.c.orig 2006-11-29 13:57:37.0 -0800 +++ ./fs/block_dev.c 2006-12-04 18:38:53.0 -0800 @@ -129,43 +129,164 @@ blkdev_get_block(struct inode *inode, se return 0; } -static int -blkdev_get_blocks(struct inode *inode, sector_t iblock, - struct buffer_head *bh, int create) +int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) This should be static. + struct kiocb* iocb = bio-bi_private; + atomic_t* bio_count = (atomic_t*) iocb-private; The * placement is wrong all over. This should be: struct kiocb *iocb = bio-bi_private; atomic_t *bio_count = (atomic_t *)iocb-private; + long res; + + if ((bio-bi_rw 1) == READ) I just wanted to complain about not using a proper helper for this, but apparently we don't have one yet.. + bio_check_pages_dirty(bio); + else { + bio_release_pages(bio); + bio_put(bio); + } + if (error) + iocb-ki_left = -EIO; + + if (atomic_dec_and_test(bio_count)) { + res = (iocb-ki_left 0) ? iocb-ki_left : iocb-ki_nbytes; + aio_complete(iocb, res, 0); } I suspect this would be a lot more readable as: if (atomic_dec_and_test(bio_count)) { if (iocb-ki_left 0) aio_complete(iocb, iocb-ki_left, 0); else aio_complete(iocb, iocb-ki_nbytes, 0); } +struct page *blk_get_page(unsigned long addr, size_t count, int rw, + struct pvec *pvec) static, again. +{ + int ret, nr_pages; + if (pvec-idx == pvec-nr) { + nr_pages = (addr + count + PAGE_SIZE - 1) / PAGE_SIZE - + addr / PAGE_SIZE; + nr_pages = min(nr_pages, VEC_SIZE); Didn't someone say you should add a macro for this in the last round of reviews? + down_read(current-mm-mmap_sem); + ret = get_user_pages(current, current-mm, addr, nr_pages, + rw==READ, 0, pvec-page, NULL); rw == READ static ssize_t blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs) + loff_t pos, unsigned long nr_segs) { - struct file *file = iocb-ki_filp; - struct inode *inode = file-f_mapping-host; + struct inode *inode = iocb-ki_filp-f_mapping-host; + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); + unsigned blocksize_mask = (1 blkbits) - 1; + unsigned long seg, nvec, cur_off, cur_len; + + unsigned long addr; + size_t count, nbytes = iocb-ki_nbytes; + loff_t size; + struct bio * bio; + atomic_t *bio_count = (atomic_t *) iocb-private; + struct page *page; + struct pvec pvec = {.nr = 0, .idx = 0, }; + + BUILD_BUG_ON(sizeof(atomic_t) sizeof(iocb-private)); + + size = i_size_read(inode); + if (pos + nbytes size) + nbytes = size - pos; + + seg = 0; + addr = (unsigned long) iov[0].iov_base; + count = iov[0].iov_len; + atomic_set(bio_count, 1); + + /* first check the alignment */ + if (addr blocksize_mask || count blocksize_mask || + pos blocksize_mask) + return -EINVAL; You only use one iovec and simply ignore all others, that's a huge regression over the existing functionality (and actually a bug that causes silent data loss) static int blkdev_writepage(struct page *page, struct writeback_control *wbc) --- ./fs/read_write.c.orig2006-11-29 13:57:37.0 -0800 +++ ./fs/read_write.c 2006-12-04 17:30:34.0 -0800 @@
Re: [patch] optimize o_direct on block device - v2
On Tue, 5 Dec 2006 11:02:30 + Christoph Hellwig [EMAIL PROTECTED] wrote: + long res; + + if ((bio-bi_rw 1) == READ) I just wanted to complain about not using a proper helper for this, but apparently we don't have one yet.. There's bio_data_dir(). - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[patch] optimize o_direct on block device - v2
This patch implements block device specific .direct_IO method instead of going through generic direct_io_worker for block device. direct_io_worker is fairly complex because it needs to handle O_DIRECT on file system, where it needs to perform block allocation, hole detection, extents file on write, and tons of other corner cases. The end result is that it takes tons of CPU time to submit an I/O. For block device, the block allocation is much simpler and a tight triple loop can be written to iterate each iovec and each page within the iovec in order to construct/prepare bio structure and then subsequently submit it to the block layer. This significantly speeds up O_D on block device. Signed-off-by: Ken Chen <[EMAIL PROTECTED]> --- Changes since v1->v2: * add BUILD_BUG_ON to ensure bio_count fit inside iocb->private * add comment that bio_alloc won't fail with GFP_KERNEL * fix back out path if get_uer_pages fail * fix back out path if iov segment doesn't align properly fs/bio.c|2 fs/block_dev.c | 173 fs/read_write.c |2 include/linux/bio.h |1 4 files changed, 150 insertions(+), 28 deletions(-) --- ./fs/block_dev.c.orig 2006-11-29 13:57:37.0 -0800 +++ ./fs/block_dev.c2006-12-04 18:38:53.0 -0800 @@ -129,43 +129,164 @@ blkdev_get_block(struct inode *inode, se return 0; } -static int -blkdev_get_blocks(struct inode *inode, sector_t iblock, - struct buffer_head *bh, int create) +int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) { - sector_t end_block = max_block(I_BDEV(inode)); - unsigned long max_blocks = bh->b_size >> inode->i_blkbits; + struct kiocb* iocb = bio->bi_private; + atomic_t* bio_count = (atomic_t*) >private; + long res; + + if ((bio->bi_rw & 1) == READ) + bio_check_pages_dirty(bio); + else { + bio_release_pages(bio); + bio_put(bio); + } - if ((iblock + max_blocks) > end_block) { - max_blocks = end_block - iblock; - if ((long)max_blocks <= 0) { - if (create) - return -EIO;/* write fully beyond EOF */ - /* -* It is a read which is fully beyond EOF. We return -* a !buffer_mapped buffer -*/ - max_blocks = 0; - } + if (error) + iocb->ki_left = -EIO; + + if (atomic_dec_and_test(bio_count)) { + res = (iocb->ki_left < 0) ? iocb->ki_left : iocb->ki_nbytes; + aio_complete(iocb, res, 0); } - bh->b_bdev = I_BDEV(inode); - bh->b_blocknr = iblock; - bh->b_size = max_blocks << inode->i_blkbits; - if (max_blocks) - set_buffer_mapped(bh); return 0; } +#define VEC_SIZE 16 +struct pvec { + unsigned short nr; + unsigned short idx; + struct page *page[VEC_SIZE]; +}; + + +struct page *blk_get_page(unsigned long addr, size_t count, int rw, + struct pvec *pvec) +{ + int ret, nr_pages; + if (pvec->idx == pvec->nr) { + nr_pages = (addr + count + PAGE_SIZE - 1) / PAGE_SIZE - + addr / PAGE_SIZE; + nr_pages = min(nr_pages, VEC_SIZE); + down_read(>mm->mmap_sem); + ret = get_user_pages(current, current->mm, addr, nr_pages, +rw==READ, 0, pvec->page, NULL); + up_read(>mm->mmap_sem); + if (ret < 0) + return ERR_PTR(ret); + pvec->nr = ret; + pvec->idx = 0; + } + return pvec->page[pvec->idx++]; +} + static ssize_t blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs) +loff_t pos, unsigned long nr_segs) { - struct file *file = iocb->ki_filp; - struct inode *inode = file->f_mapping->host; + struct inode *inode = iocb->ki_filp->f_mapping->host; + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); + unsigned blocksize_mask = (1<< blkbits) - 1; + unsigned long seg, nvec, cur_off, cur_len; + + unsigned long addr; + size_t count, nbytes = iocb->ki_nbytes; + loff_t size; + struct bio * bio; + atomic_t *bio_count = (atomic_t *) >private; + struct page *page; + struct pvec pvec = {.nr = 0, .idx = 0, }; + + BUILD_BUG_ON(sizeof(atomic_t) > sizeof(iocb->private)); + + size = i_size_read(inode); + if (pos + nbytes > size) + nbytes = size - pos; + + seg = 0; + addr = (unsigned long) iov[0].iov_base; + count = iov[0].iov_len; + atomic_set(bio_count, 1); + +
[patch] optimize o_direct on block device - v2
This patch implements block device specific .direct_IO method instead of going through generic direct_io_worker for block device. direct_io_worker is fairly complex because it needs to handle O_DIRECT on file system, where it needs to perform block allocation, hole detection, extents file on write, and tons of other corner cases. The end result is that it takes tons of CPU time to submit an I/O. For block device, the block allocation is much simpler and a tight triple loop can be written to iterate each iovec and each page within the iovec in order to construct/prepare bio structure and then subsequently submit it to the block layer. This significantly speeds up O_D on block device. Signed-off-by: Ken Chen [EMAIL PROTECTED] --- Changes since v1-v2: * add BUILD_BUG_ON to ensure bio_count fit inside iocb-private * add comment that bio_alloc won't fail with GFP_KERNEL * fix back out path if get_uer_pages fail * fix back out path if iov segment doesn't align properly fs/bio.c|2 fs/block_dev.c | 173 fs/read_write.c |2 include/linux/bio.h |1 4 files changed, 150 insertions(+), 28 deletions(-) --- ./fs/block_dev.c.orig 2006-11-29 13:57:37.0 -0800 +++ ./fs/block_dev.c2006-12-04 18:38:53.0 -0800 @@ -129,43 +129,164 @@ blkdev_get_block(struct inode *inode, se return 0; } -static int -blkdev_get_blocks(struct inode *inode, sector_t iblock, - struct buffer_head *bh, int create) +int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) { - sector_t end_block = max_block(I_BDEV(inode)); - unsigned long max_blocks = bh-b_size inode-i_blkbits; + struct kiocb* iocb = bio-bi_private; + atomic_t* bio_count = (atomic_t*) iocb-private; + long res; + + if ((bio-bi_rw 1) == READ) + bio_check_pages_dirty(bio); + else { + bio_release_pages(bio); + bio_put(bio); + } - if ((iblock + max_blocks) end_block) { - max_blocks = end_block - iblock; - if ((long)max_blocks = 0) { - if (create) - return -EIO;/* write fully beyond EOF */ - /* -* It is a read which is fully beyond EOF. We return -* a !buffer_mapped buffer -*/ - max_blocks = 0; - } + if (error) + iocb-ki_left = -EIO; + + if (atomic_dec_and_test(bio_count)) { + res = (iocb-ki_left 0) ? iocb-ki_left : iocb-ki_nbytes; + aio_complete(iocb, res, 0); } - bh-b_bdev = I_BDEV(inode); - bh-b_blocknr = iblock; - bh-b_size = max_blocks inode-i_blkbits; - if (max_blocks) - set_buffer_mapped(bh); return 0; } +#define VEC_SIZE 16 +struct pvec { + unsigned short nr; + unsigned short idx; + struct page *page[VEC_SIZE]; +}; + + +struct page *blk_get_page(unsigned long addr, size_t count, int rw, + struct pvec *pvec) +{ + int ret, nr_pages; + if (pvec-idx == pvec-nr) { + nr_pages = (addr + count + PAGE_SIZE - 1) / PAGE_SIZE - + addr / PAGE_SIZE; + nr_pages = min(nr_pages, VEC_SIZE); + down_read(current-mm-mmap_sem); + ret = get_user_pages(current, current-mm, addr, nr_pages, +rw==READ, 0, pvec-page, NULL); + up_read(current-mm-mmap_sem); + if (ret 0) + return ERR_PTR(ret); + pvec-nr = ret; + pvec-idx = 0; + } + return pvec-page[pvec-idx++]; +} + static ssize_t blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs) +loff_t pos, unsigned long nr_segs) { - struct file *file = iocb-ki_filp; - struct inode *inode = file-f_mapping-host; + struct inode *inode = iocb-ki_filp-f_mapping-host; + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); + unsigned blocksize_mask = (1 blkbits) - 1; + unsigned long seg, nvec, cur_off, cur_len; + + unsigned long addr; + size_t count, nbytes = iocb-ki_nbytes; + loff_t size; + struct bio * bio; + atomic_t *bio_count = (atomic_t *) iocb-private; + struct page *page; + struct pvec pvec = {.nr = 0, .idx = 0, }; + + BUILD_BUG_ON(sizeof(atomic_t) sizeof(iocb-private)); + + size = i_size_read(inode); + if (pos + nbytes size) + nbytes = size - pos; + + seg = 0; + addr = (unsigned long) iov[0].iov_base; + count = iov[0].iov_len; + atomic_set(bio_count, 1); + + /* first check the