[PATCH v2 22/26] block: Add bio_alloc_pages()

2012-10-15 Thread Kent Overstreet 
More utility code to replace stuff that's getting open coded.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
---
 fs/bio.c| 28 
 include/linux/bio.h |  1 +
 2 files changed, 29 insertions(+)

diff --git a/fs/bio.c b/fs/bio.c
index d88ad77..65e6eac 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -828,6 +828,34 @@ void bio_advance(struct bio *bio, unsigned bytes)
 EXPORT_SYMBOL(bio_advance);
 
 /**
+ * bio_alloc_pages - allocates a single page for each bvec in a bio
+ * @bio: bio to allocate pages for
+ * @gfp_mask: flags for allocation
+ *
+ * Allocates pages up to @bio->bi_vcnt.
+ *
+ * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages 
are
+ * freed.
+ */
+int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+   int i;
+   struct bio_vec *bv;
+
+   bio_for_each_segment_all(bv, bio, i) {
+   bv->bv_page = alloc_page(gfp_mask);
+   if (!bv->bv_page) {
+   while (bv-- != bio->bi_io_vec)
+   __free_page(bv->bv_page);
+   return -ENOMEM;
+   }
+   }
+
+   return 0;
+}
+EXPORT_SYMBOL(bio_alloc_pages);
+
+/**
  * bio_copy_data - copy contents of data buffers from one chain of bios to
  * another
  * @src: source bio list
diff --git a/include/linux/bio.h b/include/linux/bio.h
index b433ff8..bd45154 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -289,6 +289,7 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
 #endif
 
 extern void bio_copy_data(struct bio *dst, struct bio *src);
+extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 
 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 unsigned long, unsigned int, int, gfp_t);
-- 
1.7.12

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[PATCH v2 22/26] block: Add bio_alloc_pages()

2012-10-15 Thread Kent Overstreet 
More utility code to replace stuff that's getting open coded.

Signed-off-by: Kent Overstreet koverstr...@google.com
CC: Jens Axboe ax...@kernel.dk
---
 fs/bio.c| 28 
 include/linux/bio.h |  1 +
 2 files changed, 29 insertions(+)

diff --git a/fs/bio.c b/fs/bio.c
index d88ad77..65e6eac 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -828,6 +828,34 @@ void bio_advance(struct bio *bio, unsigned bytes)
 EXPORT_SYMBOL(bio_advance);
 
 /**
+ * bio_alloc_pages - allocates a single page for each bvec in a bio
+ * @bio: bio to allocate pages for
+ * @gfp_mask: flags for allocation
+ *
+ * Allocates pages up to @bio-bi_vcnt.
+ *
+ * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages 
are
+ * freed.
+ */
+int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+   int i;
+   struct bio_vec *bv;
+
+   bio_for_each_segment_all(bv, bio, i) {
+   bv-bv_page = alloc_page(gfp_mask);
+   if (!bv-bv_page) {
+   while (bv-- != bio-bi_io_vec)
+   __free_page(bv-bv_page);
+   return -ENOMEM;
+   }
+   }
+
+   return 0;
+}
+EXPORT_SYMBOL(bio_alloc_pages);
+
+/**
  * bio_copy_data - copy contents of data buffers from one chain of bios to
  * another
  * @src: source bio list
diff --git a/include/linux/bio.h b/include/linux/bio.h
index b433ff8..bd45154 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -289,6 +289,7 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
 #endif
 
 extern void bio_copy_data(struct bio *dst, struct bio *src);
+extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 
 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 unsigned long, unsigned int, int, gfp_t);
-- 
1.7.12

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Re: [PATCH v2 22/26] block: Add bio_alloc_pages()

2012-09-20 Thread Kent Overstreet 
On Thu, Sep 20, 2012 at 05:47:11PM -0700, Tejun Heo wrote:
> On Mon, Sep 10, 2012 at 05:22:33PM -0700, Kent Overstreet wrote:
> > +   bio_for_each_segment_all(bv, bio, i) {
> > +   bv->bv_page = alloc_page(gfp_mask);
> > +   if (!bv->bv_page) {
> > +   while (bv-- != bio->bi_io_vec)
> > +   __free_page(bv->bv_page);
> 
> I don't know.  I feel stupid.  I think it's because the loop variable
> changes between loop condition test and actual body of loop.  How
> about the following?  It is pointing to the member of the same array
> so I think it's not even violating pointer comparison rules.
> 
>   while (--bv >= bio->bi_io_vec)
>   __free_page(bv->bv_page);

I can't remember why I did it that way, but I think I like yours better
- I'll change it.
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Re: [PATCH v2 22/26] block: Add bio_alloc_pages()

2012-09-20 Thread Tejun Heo 
On Mon, Sep 10, 2012 at 05:22:33PM -0700, Kent Overstreet wrote:
> + bio_for_each_segment_all(bv, bio, i) {
> + bv->bv_page = alloc_page(gfp_mask);
> + if (!bv->bv_page) {
> + while (bv-- != bio->bi_io_vec)
> + __free_page(bv->bv_page);

I don't know.  I feel stupid.  I think it's because the loop variable
changes between loop condition test and actual body of loop.  How
about the following?  It is pointing to the member of the same array
so I think it's not even violating pointer comparison rules.

while (--bv >= bio->bi_io_vec)
__free_page(bv->bv_page);

-- 
tejun
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Re: [PATCH v2 22/26] block: Add bio_alloc_pages()

2012-09-20 Thread Tejun Heo 
On Mon, Sep 10, 2012 at 05:22:33PM -0700, Kent Overstreet wrote:
 + bio_for_each_segment_all(bv, bio, i) {
 + bv-bv_page = alloc_page(gfp_mask);
 + if (!bv-bv_page) {
 + while (bv-- != bio-bi_io_vec)
 + __free_page(bv-bv_page);

I don't know.  I feel stupid.  I think it's because the loop variable
changes between loop condition test and actual body of loop.  How
about the following?  It is pointing to the member of the same array
so I think it's not even violating pointer comparison rules.

while (--bv = bio-bi_io_vec)
__free_page(bv-bv_page);

-- 
tejun
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Re: [PATCH v2 22/26] block: Add bio_alloc_pages()

2012-09-20 Thread Kent Overstreet 
On Thu, Sep 20, 2012 at 05:47:11PM -0700, Tejun Heo wrote:
 On Mon, Sep 10, 2012 at 05:22:33PM -0700, Kent Overstreet wrote:
  +   bio_for_each_segment_all(bv, bio, i) {
  +   bv-bv_page = alloc_page(gfp_mask);
  +   if (!bv-bv_page) {
  +   while (bv-- != bio-bi_io_vec)
  +   __free_page(bv-bv_page);
 
 I don't know.  I feel stupid.  I think it's because the loop variable
 changes between loop condition test and actual body of loop.  How
 about the following?  It is pointing to the member of the same array
 so I think it's not even violating pointer comparison rules.
 
   while (--bv = bio-bi_io_vec)
   __free_page(bv-bv_page);

I can't remember why I did it that way, but I think I like yours better
- I'll change it.
--
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the body of a message to majord...@vger.kernel.org
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Please read the FAQ at  http://www.tux.org/lkml/

[PATCH v2 22/26] block: Add bio_alloc_pages()

2012-09-10 Thread Kent Overstreet 
More utility code to replace stuff that's getting open coded.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
---
 fs/bio.c| 28 
 include/linux/bio.h |  1 +
 2 files changed, 29 insertions(+)

diff --git a/fs/bio.c b/fs/bio.c
index d88ad77..65e6eac 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -828,6 +828,34 @@ void bio_advance(struct bio *bio, unsigned bytes)
 EXPORT_SYMBOL(bio_advance);
 
 /**
+ * bio_alloc_pages - allocates a single page for each bvec in a bio
+ * @bio: bio to allocate pages for
+ * @gfp_mask: flags for allocation
+ *
+ * Allocates pages up to @bio->bi_vcnt.
+ *
+ * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages 
are
+ * freed.
+ */
+int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+   int i;
+   struct bio_vec *bv;
+
+   bio_for_each_segment_all(bv, bio, i) {
+   bv->bv_page = alloc_page(gfp_mask);
+   if (!bv->bv_page) {
+   while (bv-- != bio->bi_io_vec)
+   __free_page(bv->bv_page);
+   return -ENOMEM;
+   }
+   }
+
+   return 0;
+}
+EXPORT_SYMBOL(bio_alloc_pages);
+
+/**
  * bio_copy_data - copy contents of data buffers from one chain of bios to
  * another
  * @src: source bio list
diff --git a/include/linux/bio.h b/include/linux/bio.h
index b433ff8..bd45154 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -289,6 +289,7 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
 #endif
 
 extern void bio_copy_data(struct bio *dst, struct bio *src);
+extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 
 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 unsigned long, unsigned int, int, gfp_t);
-- 
1.7.12

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[PATCH v2 22/26] block: Add bio_alloc_pages()

2012-09-10 Thread Kent Overstreet 
More utility code to replace stuff that's getting open coded.

Signed-off-by: Kent Overstreet koverstr...@google.com
CC: Jens Axboe ax...@kernel.dk
---
 fs/bio.c| 28 
 include/linux/bio.h |  1 +
 2 files changed, 29 insertions(+)

diff --git a/fs/bio.c b/fs/bio.c
index d88ad77..65e6eac 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -828,6 +828,34 @@ void bio_advance(struct bio *bio, unsigned bytes)
 EXPORT_SYMBOL(bio_advance);
 
 /**
+ * bio_alloc_pages - allocates a single page for each bvec in a bio
+ * @bio: bio to allocate pages for
+ * @gfp_mask: flags for allocation
+ *
+ * Allocates pages up to @bio-bi_vcnt.
+ *
+ * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages 
are
+ * freed.
+ */
+int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+   int i;
+   struct bio_vec *bv;
+
+   bio_for_each_segment_all(bv, bio, i) {
+   bv-bv_page = alloc_page(gfp_mask);
+   if (!bv-bv_page) {
+   while (bv-- != bio-bi_io_vec)
+   __free_page(bv-bv_page);
+   return -ENOMEM;
+   }
+   }
+
+   return 0;
+}
+EXPORT_SYMBOL(bio_alloc_pages);
+
+/**
  * bio_copy_data - copy contents of data buffers from one chain of bios to
  * another
  * @src: source bio list
diff --git a/include/linux/bio.h b/include/linux/bio.h
index b433ff8..bd45154 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -289,6 +289,7 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
 #endif
 
 extern void bio_copy_data(struct bio *dst, struct bio *src);
+extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 
 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 unsigned long, unsigned int, int, gfp_t);
-- 
1.7.12

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