[PATCH 1/2] btrfs: Factor out allocating an array of pages.

Sweet Tea Dorminy
2022-03-28T20:14:42Z

Several functions currently populate an array of page pointers one
allocated page at a time; factor out the common code so as to allow
improvements to all of the sites at once.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
fs/btrfs/check-integrity.c | 8 +++-----
fs/btrfs/compression.c | 37 +++++++++++++++--------------------
fs/btrfs/ctree.c | 25 ++++++++++++++++++++++++
fs/btrfs/ctree.h | 2 ++
fs/btrfs/extent_io.c | 40 +++++++++++++++++++++++---------------
fs/btrfs/inode.c | 10 ++++------
fs/btrfs/raid56.c | 30 ++++------------------------
7 files changed, 78 insertions(+), 74 deletions(-)

diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index 7e9f90fa0388..366d5a80f3c5 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -1553,11 +1553,9 @@ static int btrfsic_read_block(struct btrfsic_state *state,
return -ENOMEM;
block_ctx->datav = block_ctx->mem_to_free;
block_ctx->pagev = (struct page **)(block_ctx->datav + num_pages);
- for (i = 0; i < num_pages; i++) {
- block_ctx->pagev[i] = alloc_page(GFP_NOFS);
- if (!block_ctx->pagev[i])
- return -1;
- }
+ ret = btrfs_alloc_page_array(num_pages, block_ctx->pagev);
+ if (ret)
+ return ret;

dev_bytenr = block_ctx->dev_bytenr;
for (i = 0; i < num_pages;) {
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index be476f094300..0fc663b757fb 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -801,8 +801,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
struct extent_map_tree *em_tree;
struct compressed_bio *cb;
unsigned int compressed_len;
- unsigned int nr_pages;
- unsigned int pg_index;
struct bio *comp_bio = NULL;
const u64 disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
u64 cur_disk_byte = disk_bytenr;
@@ -812,7 +810,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
u64 em_start;
struct extent_map *em;
blk_status_t ret;
- int faili = 0;
+ int r;
+ int i;
u8 *sums;

em_tree = &BTRFS_I(inode)->extent_tree;
@@ -855,25 +854,20 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
cb->compress_type = extent_compress_type(bio_flags);
cb->orig_bio = bio;

- nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
- cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
+ cb->nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
+ cb->compressed_pages = kcalloc(cb->nr_pages, sizeof(struct page *),
GFP_NOFS);
if (!cb->compressed_pages) {
ret = BLK_STS_RESOURCE;
- goto fail1;
+ goto fail;
}

- for (pg_index = 0; pg_index < nr_pages; pg_index++) {
- cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS);
- if (!cb->compressed_pages[pg_index]) {
- faili = pg_index - 1;
- ret = BLK_STS_RESOURCE;
- goto fail2;
- }
+ r = btrfs_alloc_page_array(cb->nr_pages, cb->compressed_pages);
+ if (r) {
+ ret = BLK_STS_RESOURCE;
+ goto fail;
}
- faili = nr_pages - 1;
- cb->nr_pages = nr_pages;
-
+
add_ra_bio_pages(inode, em_start + em_len, cb);

/* include any pages we added in add_ra-bio_pages */
@@ -949,14 +943,15 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
}
return BLK_STS_OK;

-fail2:
- while (faili >= 0) {
- __free_page(cb->compressed_pages[faili]);
- faili--;
+fail:
+ if (cb->compressed_pages) {
+ for (i = 0; i < cb->nr_pages; i++) {
+ if (cb->compressed_pages[i])
+ __free_page(cb->compressed_pages[i]);
+ }
}

kfree(cb->compressed_pages);
-fail1:
kfree(cb);
out:
free_extent_map(em);
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 1e24695ede0a..4e81e75c8e7c 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -90,6 +90,31 @@ void btrfs_free_path(struct btrfs_path *p)
kmem_cache_free(btrfs_path_cachep, p);
}

+/**
+ * btrfs_alloc_page_array() - allocate an array of pages.
+ *
+ * @nr_pages: the number of pages to request
+ * @page_array: the array to fill with pages. Any existing non-null entries in
+ * the array will be skipped.
+ *
+ * Return: 0 if all pages were able to be allocated; -ENOMEM otherwise, and the
+ * caller is responsible for freeing all non-null page pointers in the array.
+ */
+int btrfs_alloc_page_array(unsigned long nr_pages, struct page **page_array)
+{
+ int i;
+ for (i = 0; i < nr_pages; i++) {
+ struct page *page;
+ if (page_array[i])
+ continue;
+ page = alloc_page(GFP_NOFS);
+ if (!page)
+ return -ENOMEM;
+ page_array[i] = page;
+ }
+ return 0;
+}
+
/*
* path release drops references on the extent buffers in the path
* and it drops any locks held by this path
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7328fb17b7f5..e835a2bfb60a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2969,6 +2969,8 @@ void btrfs_release_path(struct btrfs_path *p);
struct btrfs_path *btrfs_alloc_path(void);
void btrfs_free_path(struct btrfs_path *p);

+int btrfs_alloc_page_array(unsigned long nr_pages, struct page **page_array);
+
int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct btrfs_path *path, int slot, int nr);
static inline int btrfs_del_item(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 53b59944013f..c1c8d770f43a 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5898,9 +5898,9 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src)
{
int i;
- struct page *p;
struct extent_buffer *new;
int num_pages = num_extent_pages(src);
+ int r;

new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
if (new == NULL)
@@ -5913,22 +5913,23 @@ struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src)
*/
set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);

+ memset(new->pages, 0, sizeof(*new->pages) * num_pages);
+ r = btrfs_alloc_page_array(num_pages, new->pages);
+ if (r) {
+ btrfs_release_extent_buffer(new);
+ return NULL;
+ }
+
for (i = 0; i < num_pages; i++) {
int ret;
+ struct page *p = new->pages[i];

- p = alloc_page(GFP_NOFS);
- if (!p) {
- btrfs_release_extent_buffer(new);
- return NULL;
- }
ret = attach_extent_buffer_page(new, p, NULL);
if (ret < 0) {
- put_page(p);
btrfs_release_extent_buffer(new);
return NULL;
}
WARN_ON(PageDirty(p));
- new->pages[i] = p;
copy_page(page_address(p), page_address(src->pages[i]));
}
set_extent_buffer_uptodate(new);
@@ -5942,31 +5943,38 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
struct extent_buffer *eb;
int num_pages;
int i;
+ int r;

eb = __alloc_extent_buffer(fs_info, start, len);
if (!eb)
return NULL;

num_pages = num_extent_pages(eb);
+ r = btrfs_alloc_page_array(num_pages, eb->pages);
+ if (r)
+ goto err;
+
for (i = 0; i < num_pages; i++) {
int ret;
+ struct page *p = eb->pages[i];

- eb->pages[i] = alloc_page(GFP_NOFS);
- if (!eb->pages[i])
- goto err;
- ret = attach_extent_buffer_page(eb, eb->pages[i], NULL);
- if (ret < 0)
+ ret = attach_extent_buffer_page(eb, p, NULL);
+ if (ret < 0) {
goto err;
+ }
}
+
set_extent_buffer_uptodate(eb);
btrfs_set_header_nritems(eb, 0);
set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);

return eb;
err:
- for (; i > 0; i--) {
- detach_extent_buffer_page(eb, eb->pages[i - 1]);
- __free_page(eb->pages[i - 1]);
+ for (i = 0; i < num_pages; i++) {
+ if (eb->pages[i]) {
+ detach_extent_buffer_page(eb, eb->pages[i]);
+ __free_page(eb->pages[i]);
+ }
}
__free_extent_buffer(eb);
return NULL;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c7b15634fe70..121858652a09 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -10427,13 +10427,11 @@ static ssize_t btrfs_encoded_read_regular(struct kiocb *iocb,
pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
if (!pages)
return -ENOMEM;
- for (i = 0; i < nr_pages; i++) {
- pages[i] = alloc_page(GFP_NOFS);
- if (!pages[i]) {
- ret = -ENOMEM;
- goto out;
+ ret = btrfs_alloc_page_array(nr_pages, pages);
+ if (ret) {
+ ret = -ENOMEM;
+ goto out;
}
- }

ret = btrfs_encoded_read_regular_fill_pages(inode, start, disk_bytenr,
disk_io_size, pages);
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 0e239a4c3b26..ea7a9152b1cc 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1026,37 +1026,15 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info,
/* allocate pages for all the stripes in the bio, including parity */
static int alloc_rbio_pages(struct btrfs_raid_bio *rbio)
{
- int i;
- struct page *page;
-
- for (i = 0; i < rbio->nr_pages; i++) {
- if (rbio->stripe_pages[i])
- continue;
- page = alloc_page(GFP_NOFS);
- if (!page)
- return -ENOMEM;
- rbio->stripe_pages[i] = page;
- }
- return 0;
+ return btrfs_alloc_page_array(rbio->nr_pages, rbio->stripe_pages);
}

/* only allocate pages for p/q stripes */
static int alloc_rbio_parity_pages(struct btrfs_raid_bio *rbio)
{
- int i;
- struct page *page;
-
- i = rbio_stripe_page_index(rbio, rbio->nr_data, 0);
-
- for (; i < rbio->nr_pages; i++) {
- if (rbio->stripe_pages[i])
- continue;
- page = alloc_page(GFP_NOFS);
- if (!page)
- return -ENOMEM;
- rbio->stripe_pages[i] = page;
- }
- return 0;
+ int data_pages = rbio_stripe_page_index(rbio, rbio->nr_data, 0);
+ return btrfs_alloc_page_array(rbio->nr_pages - data_pages,
+ rbio->stripe_pages + data_pages);
}

/*
--
2.35.1