block: Add bio_for_each_segment_all()

commit d74c6d514fe314b8bdab58b487b25992291577ec upstream.

__bio_for_each_segment() iterates bvecs from the specified index
instead of bio->bv_idx.  Currently, the only usage is to walk all the
bvecs after the bio has been advanced by specifying 0 index.

For immutable bvecs, we need to split these apart;
bio_for_each_segment() is going to have a different implementation.
This will also help document the intent of code that's using it -
bio_for_each_segment_all() is only legal to use for code that owns the
bio.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Neil Brown <neilb@suse.de>
CC: Boaz Harrosh <bharrosh@panasas.com>
[bwh: Backported to 3.2: drop inapplicable change to drivers/block/rbd.c.
 This is a prerequisite for commit 35dc248383bb 'sg: Fix user memory
 corruption when SG_IO is interrupted by a signal']
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 298e02a..c706a7b 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1139,7 +1139,7 @@ read_again:
                         * know the original bi_idx, so we just free
                         * them all
                         */
-                       __bio_for_each_segment(bvec, mbio, j, 0)
+                       bio_for_each_segment_all(bvec, mbio, j)
                                bvec->bv_page = r1_bio->behind_bvecs[j].bv_page;
                        if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
                                atomic_inc(&r1_bio->behind_remaining);

diff --git a/fs/bio.c b/fs/bio.c
index 4fc4dbb..27116a4 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -734,7 +734,7 @@ static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
        int iov_idx = 0;
        unsigned int iov_off = 0;
 
-       __bio_for_each_segment(bvec, bio, i, 0) {
+       bio_for_each_segment_all(bvec, bio, i) {
                char *bv_addr = page_address(bvec->bv_page);
                unsigned int bv_len = iovecs[i].bv_len;
 
@@ -916,7 +916,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
        return bio;
 cleanup:
        if (!map_data)
-               bio_for_each_segment(bvec, bio, i)
+               bio_for_each_segment_all(bvec, bio, i)
                        __free_page(bvec->bv_page);
 
        bio_put(bio);
@@ -1130,7 +1130,7 @@ static void __bio_unmap_user(struct bio *bio)
        /*
         * make sure we dirty pages we wrote to
         */
-       __bio_for_each_segment(bvec, bio, i, 0) {
+       bio_for_each_segment_all(bvec, bio, i) {
                if (bio_data_dir(bio) == READ)
                        set_page_dirty_lock(bvec->bv_page);
 
@@ -1236,7 +1236,7 @@ static void bio_copy_kern_endio(struct bio *bio, int err)
        int i;
        char *p = bmd->sgvecs[0].iov_base;
 
-       __bio_for_each_segment(bvec, bio, i, 0) {
+       bio_for_each_segment_all(bvec, bio, i) {
                char *addr = page_address(bvec->bv_page);
                int len = bmd->iovecs[i].bv_len;
 
@@ -1276,7 +1276,7 @@ struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
        if (!reading) {
                void *p = data;
 
-               bio_for_each_segment(bvec, bio, i) {
+               bio_for_each_segment_all(bvec, bio, i) {
                        char *addr = page_address(bvec->bv_page);
 
                        memcpy(addr, p, bvec->bv_len);
@@ -1556,7 +1556,7 @@ sector_t bio_sector_offset(struct bio *bio, unsigned short index,
        if (index >= bio->bi_idx)
                index = bio->bi_vcnt - 1;
 
-       __bio_for_each_segment(bv, bio, i, 0) {
+       bio_for_each_segment_all(bv, bio, i) {
                if (i == index) {
                        if (offset > bv->bv_offset)
                                sectors += (offset - bv->bv_offset) / sector_sz;

diff --git a/fs/exofs/ore.c b/fs/exofs/ore.c
index 1585db1..26bb512 100644 (file)
--- a/fs/exofs/ore.c
+++ b/fs/exofs/ore.c
@@ -401,7 +401,7 @@ static void _clear_bio(struct bio *bio)
        struct bio_vec *bv;
        unsigned i;
 
-       __bio_for_each_segment(bv, bio, i, 0) {
+       bio_for_each_segment_all(bv, bio, i) {
                unsigned this_count = bv->bv_len;
 
                if (likely(PAGE_SIZE == this_count))

diff --git a/fs/exofs/ore_raid.c b/fs/exofs/ore_raid.c
index fff2070..2c64826 100644 (file)
--- a/fs/exofs/ore_raid.c
+++ b/fs/exofs/ore_raid.c
@@ -432,7 +432,7 @@ static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
                if (!bio)
                        continue;
 
-               __bio_for_each_segment(bv, bio, i, 0) {
+               bio_for_each_segment_all(bv, bio, i) {
                        struct page *page = bv->bv_page;
 
                        SetPageUptodate(page);

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 847994a..e868554 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -135,16 +135,27 @@ static inline int bio_has_allocated_vec(struct bio *bio)
 #define bio_io_error(bio) bio_endio((bio), -EIO)
 
 /*
- * drivers should not use the __ version unless they _really_ want to
- * run through the entire bio and not just pending pieces
+ * drivers should not use the __ version unless they _really_ know what
+ * they're doing
  */
 #define __bio_for_each_segment(bvl, bio, i, start_idx)                 \
        for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
             i < (bio)->bi_vcnt;                                        \
             bvl++, i++)
 
+/*
+ * drivers should _never_ use the all version - the bio may have been split
+ * before it got to the driver and the driver won't own all of it
+ */
+#define bio_for_each_segment_all(bvl, bio, i)                          \
+       for (i = 0;                                                     \
+            bvl = bio_iovec_idx((bio), (i)), i < (bio)->bi_vcnt;       \
+            i++)
+
 #define bio_for_each_segment(bvl, bio, i)                              \
-       __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
+       for (i = (bio)->bi_idx;                                         \
+            bvl = bio_iovec_idx((bio), (i)), i < (bio)->bi_vcnt;       \
+            i++)
 
 /*
  * get a reference to a bio, so it won't disappear. the intended use is

diff --git a/mm/bounce.c b/mm/bounce.c
index 4e9ae72..f71a3b3 100644 (file)
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -132,7 +132,7 @@ static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
        /*
         * free up bounce indirect pages used
         */
-       __bio_for_each_segment(bvec, bio, i, 0) {
+       bio_for_each_segment_all(bvec, bio, i) {
                org_vec = bio_orig->bi_io_vec + i;
                if (bvec->bv_page == org_vec->bv_page)
                        continue;