exofs: convert io_state to use pages array instead of bio at input

* inode.c operations are full-pages based, and not actually
  true scatter-gather
* Lets us use more pages at once upto 512 (from 249) in 64 bit
* Brings us much much closer to be able to use exofs's io_state engine
  from objlayout driver. (Once I decide where to put the common code)

After RAID0 patch the outer (input) bio was never used as a bio, but
was simply a page carrier into the raid engine. Even in the simple
mirror/single-dev arrangement pages info was copied into a second bio.
It is now easer to just pass a pages array into the io_state and prepare
bio(s) once.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

diff --git a/fs/exofs/exofs.h b/fs/exofs/exofs.h
index 0d8a34b..acfebd3 100644 (file)
--- a/fs/exofs/exofs.h
+++ b/fs/exofs/exofs.h
@@ -128,7 +128,10 @@ struct exofs_io_state {
        loff_t                  offset;
        unsigned long           length;
        void                    *kern_buff;
-       struct bio              *bio;
+
+       struct page             **pages;
+       unsigned                nr_pages;
+       unsigned                pgbase;
 
        /* Attributes */
        unsigned                in_attr_len;

diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index 2b3163e..6ca0b01 100644 (file)
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -41,16 +41,18 @@
 
 enum { BIO_MAX_PAGES_KMALLOC =
                (PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec),
+       MAX_PAGES_KMALLOC =
+               PAGE_SIZE / sizeof(struct page *),
 };
 
 struct page_collect {
        struct exofs_sb_info *sbi;
-       struct request_queue *req_q;
        struct inode *inode;
        unsigned expected_pages;
        struct exofs_io_state *ios;
 
-       struct bio *bio;
+       struct page **pages;
+       unsigned alloc_pages;
        unsigned nr_pages;
        unsigned long length;
        loff_t pg_first; /* keep 64bit also in 32-arches */
@@ -62,15 +64,12 @@ static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,
        struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
 
        pcol->sbi = sbi;
-       /* Create master bios on first Q, later on cloning, each clone will be
-        * allocated on it's destination Q
-        */
-       pcol->req_q = osd_request_queue(sbi->layout.s_ods[0]);
        pcol->inode = inode;
        pcol->expected_pages = expected_pages;
 
        pcol->ios = NULL;
-       pcol->bio = NULL;
+       pcol->pages = NULL;
+       pcol->alloc_pages = 0;
        pcol->nr_pages = 0;
        pcol->length = 0;
        pcol->pg_first = -1;
@@ -80,7 +79,8 @@ static void _pcol_reset(struct page_collect *pcol)
 {
        pcol->expected_pages -= min(pcol->nr_pages, pcol->expected_pages);
 
-       pcol->bio = NULL;
+       pcol->pages = NULL;
+       pcol->alloc_pages = 0;
        pcol->nr_pages = 0;
        pcol->length = 0;
        pcol->pg_first = -1;
@@ -90,13 +90,13 @@ static void _pcol_reset(struct page_collect *pcol)
         * it might not end here. don't be left with nothing
         */
        if (!pcol->expected_pages)
-               pcol->expected_pages = BIO_MAX_PAGES_KMALLOC;
+               pcol->expected_pages = MAX_PAGES_KMALLOC;
 }
 
 static int pcol_try_alloc(struct page_collect *pcol)
 {
-       int pages = min_t(unsigned, pcol->expected_pages,
-                         BIO_MAX_PAGES_KMALLOC);
+       unsigned pages = min_t(unsigned, pcol->expected_pages,
+                         MAX_PAGES_KMALLOC);
 
        if (!pcol->ios) { /* First time allocate io_state */
                int ret = exofs_get_io_state(&pcol->sbi->layout, &pcol->ios);
@@ -105,23 +105,28 @@ static int pcol_try_alloc(struct page_collect *pcol)
                        return ret;
        }
 
+       /* TODO: easily support bio chaining */
+       pages =  min_t(unsigned, pages,
+                      pcol->sbi->layout.group_width * BIO_MAX_PAGES_KMALLOC);
+
        for (; pages; pages >>= 1) {
-               pcol->bio = bio_kmalloc(GFP_KERNEL, pages);
-               if (likely(pcol->bio))
+               pcol->pages = kmalloc(pages * sizeof(struct page *),
+                                     GFP_KERNEL);
+               if (likely(pcol->pages)) {
+                       pcol->alloc_pages = pages;
                        return 0;
+               }
        }
 
-       EXOFS_ERR("Failed to bio_kmalloc expected_pages=%u\n",
+       EXOFS_ERR("Failed to kmalloc expected_pages=%u\n",
                  pcol->expected_pages);
        return -ENOMEM;
 }
 
 static void pcol_free(struct page_collect *pcol)
 {
-       if (pcol->bio) {
-               bio_put(pcol->bio);
-               pcol->bio = NULL;
-       }
+       kfree(pcol->pages);
+       pcol->pages = NULL;
 
        if (pcol->ios) {
                exofs_put_io_state(pcol->ios);
@@ -132,11 +137,10 @@ static void pcol_free(struct page_collect *pcol)
 static int pcol_add_page(struct page_collect *pcol, struct page *page,
                         unsigned len)
 {
-       int added_len = bio_add_pc_page(pcol->req_q, pcol->bio, page, len, 0);
-       if (unlikely(len != added_len))
+       if (unlikely(pcol->nr_pages >= pcol->alloc_pages))
                return -ENOMEM;
 
-       ++pcol->nr_pages;
+       pcol->pages[pcol->nr_pages++] = page;
        pcol->length += len;
        return 0;
 }
@@ -181,7 +185,6 @@ static void update_write_page(struct page *page, int ret)
  */
 static int __readpages_done(struct page_collect *pcol, bool do_unlock)
 {
-       struct bio_vec *bvec;
        int i;
        u64 resid;
        u64 good_bytes;
@@ -198,8 +201,8 @@ static int __readpages_done(struct page_collect *pcol, bool do_unlock)
                     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,
                     pcol->nr_pages);
 
-       __bio_for_each_segment(bvec, pcol->bio, i, 0) {
-               struct page *page = bvec->bv_page;
+       for (i = 0; i < pcol->nr_pages; i++) {
+               struct page *page = pcol->pages[i];
                struct inode *inode = page->mapping->host;
                int page_stat;
 
@@ -218,7 +221,7 @@ static int __readpages_done(struct page_collect *pcol, bool do_unlock)
                ret = update_read_page(page, page_stat);
                if (do_unlock)
                        unlock_page(page);
-               length += bvec->bv_len;
+               length += PAGE_SIZE;
        }
 
        pcol_free(pcol);
@@ -238,11 +241,10 @@ static void readpages_done(struct exofs_io_state *ios, void *p)
 
 static void _unlock_pcol_pages(struct page_collect *pcol, int ret, int rw)
 {
-       struct bio_vec *bvec;
        int i;
 
-       __bio_for_each_segment(bvec, pcol->bio, i, 0) {
-               struct page *page = bvec->bv_page;
+       for (i = 0; i < pcol->nr_pages; i++) {
+               struct page *page = pcol->pages[i];
 
                if (rw == READ)
                        update_read_page(page, ret);
@@ -260,13 +262,14 @@ static int read_exec(struct page_collect *pcol, bool is_sync)
        struct page_collect *pcol_copy = NULL;
        int ret;
 
-       if (!pcol->bio)
+       if (!pcol->pages)
                return 0;
 
        /* see comment in _readpage() about sync reads */
        WARN_ON(is_sync && (pcol->nr_pages != 1));
 
-       ios->bio = pcol->bio;
+       ios->pages = pcol->pages;
+       ios->nr_pages = pcol->nr_pages;
        ios->length = pcol->length;
        ios->offset = pcol->pg_first << PAGE_CACHE_SHIFT;
 
@@ -366,7 +369,7 @@ try_again:
                goto try_again;
        }
 
-       if (!pcol->bio) {
+       if (!pcol->pages) {
                ret = pcol_try_alloc(pcol);
                if (unlikely(ret))
                        goto fail;
@@ -448,7 +451,6 @@ static int exofs_readpage(struct file *file, struct page *page)
 static void writepages_done(struct exofs_io_state *ios, void *p)
 {
        struct page_collect *pcol = p;
-       struct bio_vec *bvec;
        int i;
        u64 resid;
        u64  good_bytes;
@@ -467,8 +469,8 @@ static void writepages_done(struct exofs_io_state *ios, void *p)
                     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,
                     pcol->nr_pages);
 
-       __bio_for_each_segment(bvec, pcol->bio, i, 0) {
-               struct page *page = bvec->bv_page;
+       for (i = 0; i < pcol->nr_pages; i++) {
+               struct page *page = pcol->pages[i];
                struct inode *inode = page->mapping->host;
                int page_stat;
 
@@ -485,7 +487,7 @@ static void writepages_done(struct exofs_io_state *ios, void *p)
                EXOFS_DBGMSG2("    writepages_done(0x%lx, 0x%lx) status=%d\n",
                             inode->i_ino, page->index, page_stat);
 
-               length += bvec->bv_len;
+               length += PAGE_SIZE;
        }
 
        pcol_free(pcol);
@@ -500,7 +502,7 @@ static int write_exec(struct page_collect *pcol)
        struct page_collect *pcol_copy = NULL;
        int ret;
 
-       if (!pcol->bio)
+       if (!pcol->pages)
                return 0;
 
        pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
@@ -512,9 +514,8 @@ static int write_exec(struct page_collect *pcol)
 
        *pcol_copy = *pcol;
 
-       pcol_copy->bio->bi_rw |= (1 << BIO_RW); /* FIXME: bio_set_dir() */
-
-       ios->bio = pcol_copy->bio;
+       ios->pages = pcol_copy->pages;
+       ios->nr_pages = pcol_copy->nr_pages;
        ios->offset = pcol_copy->pg_first << PAGE_CACHE_SHIFT;
        ios->length = pcol_copy->length;
        ios->done = writepages_done;
@@ -605,7 +606,7 @@ try_again:
                goto try_again;
        }
 
-       if (!pcol->bio) {
+       if (!pcol->pages) {
                ret = pcol_try_alloc(pcol);
                if (unlikely(ret))
                        goto fail;

diff --git a/fs/exofs/ios.c b/fs/exofs/ios.c
index 6e446b2..263052c 100644 (file)
--- a/fs/exofs/ios.c
+++ b/fs/exofs/ios.c
@@ -283,10 +283,11 @@ static void _offset_dev_unit_off(struct exofs_io_state *ios, u64 file_offset,
        *dev = stripe_mod / stripe_unit * ios->layout->mirrors_p1;
 }
 
-static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_bvec,
-                    struct exofs_per_dev_state *per_dev, int cur_len)
+static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_pg,
+               unsigned pgbase, struct exofs_per_dev_state *per_dev,
+               int cur_len)
 {
-       unsigned bv = *cur_bvec;
+       unsigned pg = *cur_pg;
        struct request_queue *q =
                        osd_request_queue(exofs_ios_od(ios, per_dev->dev));
 
@@ -295,7 +296,7 @@ static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_bvec,
        if (per_dev->bio == NULL) {
                unsigned pages_in_stripe = ios->layout->group_width *
                                        (ios->layout->stripe_unit / PAGE_SIZE);
-               unsigned bio_size = (ios->bio->bi_vcnt + pages_in_stripe) /
+               unsigned bio_size = (ios->nr_pages + pages_in_stripe) /
                                                ios->layout->group_width;
 
                per_dev->bio = bio_kmalloc(GFP_KERNEL, bio_size);
@@ -307,21 +308,22 @@ static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_bvec,
        }
 
        while (cur_len > 0) {
-               int added_len;
-               struct bio_vec *bvec = &ios->bio->bi_io_vec[bv];
+               unsigned pglen = min_t(unsigned, PAGE_SIZE - pgbase, cur_len);
+               unsigned added_len;
 
-               BUG_ON(ios->bio->bi_vcnt <= bv);
-               cur_len -= bvec->bv_len;
+               BUG_ON(ios->nr_pages <= pg);
+               cur_len -= pglen;
 
-               added_len = bio_add_pc_page(q, per_dev->bio, bvec->bv_page,
-                                           bvec->bv_len, bvec->bv_offset);
-               if (unlikely(bvec->bv_len != added_len))
+               added_len = bio_add_pc_page(q, per_dev->bio, ios->pages[pg],
+                                           pglen, pgbase);
+               if (unlikely(pglen != added_len))
                        return -ENOMEM;
-               ++bv;
+               pgbase = 0;
+               ++pg;
        }
        BUG_ON(cur_len);
 
-       *cur_bvec = bv;
+       *cur_pg = pg;
        return 0;
 }
 
@@ -332,10 +334,10 @@ static int _prepare_for_striping(struct exofs_io_state *ios)
        unsigned stripe_unit = ios->layout->stripe_unit;
        unsigned comp = 0;
        unsigned stripes = 0;
-       unsigned cur_bvec = 0;
-       int ret;
+       unsigned cur_pg = 0;
+       int ret = 0;
 
-       if (!ios->bio) {
+       if (!ios->pages) {
                if (ios->kern_buff) {
                        struct exofs_per_dev_state *per_dev = &ios->per_dev[0];
                        unsigned unit_off;
@@ -352,7 +354,7 @@ static int _prepare_for_striping(struct exofs_io_state *ios)
 
        while (length) {
                struct exofs_per_dev_state *per_dev = &ios->per_dev[comp];
-               unsigned cur_len;
+               unsigned cur_len, page_off;
 
                if (!per_dev->length) {
                        unsigned unit_off;
@@ -362,11 +364,15 @@ static int _prepare_for_striping(struct exofs_io_state *ios)
                        stripes++;
                        cur_len = min_t(u64, stripe_unit - unit_off, length);
                        offset += cur_len;
+                       page_off = unit_off & ~PAGE_MASK;
+                       BUG_ON(page_off != ios->pgbase);
                } else {
                        cur_len = min_t(u64, stripe_unit, length);
+                       page_off = 0;
                }
 
-               ret = _add_stripe_unit(ios, &cur_bvec, per_dev, cur_len);
+               ret = _add_stripe_unit(ios, &cur_pg, page_off , per_dev,
+                                      cur_len);
                if (unlikely(ret))
                        goto out;
 
@@ -448,7 +454,7 @@ static int _sbi_write_mirror(struct exofs_io_state *ios, int cur_comp)
                per_dev->or = or;
                per_dev->offset = master_dev->offset;
 
-               if (ios->bio) {
+               if (ios->pages) {
                        struct bio *bio;
 
                        if (per_dev != master_dev) {
@@ -541,7 +547,7 @@ static int _sbi_read_mirror(struct exofs_io_state *ios, unsigned cur_comp)
        }
        per_dev->or = or;
 
-       if (ios->bio) {
+       if (ios->pages) {
                osd_req_read(or, &ios->obj, per_dev->offset,
                                per_dev->bio, per_dev->length);
                EXOFS_DBGMSG("read(0x%llx) offset=0x%llx length=0x%llx"