OK Now we start to read and write from osd-objects. We try to
collect at most contiguous pages as possible in a single write/read.
The first page index is the object's offset.
TODO:
In 64-bit a single bio can carry at most 128 pages.
Add support of chaining multiple bios
Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
---
fs/exofs/exofs.h | 6 +
fs/exofs/inode.c | 697 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 703 insertions(+), 0 deletions(-)
diff --git a/fs/exofs/exofs.h b/fs/exofs/exofs.h
index 825454d..0276242 100644
--- a/fs/exofs/exofs.h
+++ b/fs/exofs/exofs.h
@@ -130,6 +130,9 @@ static inline struct exofs_i_info *exofs_i(struct inode *inode)
/* inode.c */
void exofs_truncate(struct inode *inode);
int exofs_setattr(struct dentry *, struct iattr *);
+int exofs_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata);
/*********************
* operation vectors *
@@ -138,6 +141,9 @@ int exofs_setattr(struct dentry *, struct iattr *);
extern const struct inode_operations exofs_file_inode_operations;
extern const struct file_operations exofs_file_operations;
+/* inode.c */
+extern const struct address_space_operations exofs_aops;
+
/* symlink.c */
extern const struct inode_operations exofs_symlink_inode_operations;
extern const struct inode_operations exofs_fast_symlink_inode_operations;
diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index b0bda1e..a3691d8 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -35,6 +35,7 @@
#include <linux/writeback.h>
#include <linux/buffer_head.h>
+#include <scsi/scsi_device.h>
#include "exofs.h"
@@ -42,6 +43,702 @@
# define EXOFS_DEBUG_OBJ_ISIZE 1
#endif
+struct page_collect {
+ struct exofs_sb_info *sbi;
+ struct request_queue *req_q;
+ struct inode *inode;
+ unsigned expected_pages;
+
+ struct bio *bio;
+ unsigned nr_pages;
+ unsigned long length;
+ loff_t pg_first; /* keep 64bit also in 32-arches */
+};
+
+static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,
+ struct inode *inode)
+{
+ struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
+ struct request_queue *req_q = sbi->s_dev->scsi_device->request_queue;
+
+ pcol->sbi = sbi;
+ pcol->req_q = req_q;
+ pcol->inode = inode;
+ pcol->expected_pages = expected_pages;
+
+ pcol->bio = NULL;
+ pcol->nr_pages = 0;
+ pcol->length = 0;
+ pcol->pg_first = -1;
+
+ EXOFS_DBGMSG("_pcol_init ino=0x%lx expected_pages=%u\n", inode->i_ino,
+ expected_pages);
+}
+
+static void _pcol_reset(struct page_collect *pcol)
+{
+ pcol->expected_pages -= min(pcol->nr_pages, pcol->expected_pages);
+
+ pcol->bio = NULL;
+ pcol->nr_pages = 0;
+ pcol->length = 0;
+ pcol->pg_first = -1;
+ EXOFS_DBGMSG("_pcol_reset ino=0x%lx expected_pages=%u\n",
+ pcol->inode->i_ino, pcol->expected_pages);
+
+ /* this is probably the end of the loop but in writes
+ * it might not end here. don't be left with nothing
+ */
+ if (!pcol->expected_pages)
+ pcol->expected_pages = 128;
+}
+
+static int pcol_try_alloc(struct page_collect *pcol)
+{
+ int pages = min_t(unsigned, pcol->expected_pages, BIO_MAX_PAGES);
+
+ for (; pages; pages >>= 1) {
+ pcol->bio = bio_alloc(GFP_KERNEL, pages);
+ if (likely(pcol->bio))
+ return 0;
+ }
+
+ EXOFS_ERR("Failed to kcalloc expected_pages=%u\n",
+ pcol->expected_pages);
+ return -ENOMEM;
+}
+
+static void pcol_free(struct page_collect *pcol)
+{
+ bio_put(pcol->bio);
+ pcol->bio = NULL;
+}
+
+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))
+ return -ENOMEM;
+
+ ++pcol->nr_pages;
+ pcol->length += len;
+ return 0;
+}
+
+static int update_read_page(struct page *page, int ret)
+{
+ if (ret == 0) {
+ /* Everything is OK */
+ SetPageUptodate(page);
+ if (PageError(page))
+ ClearPageError(page);
+ } else if (ret == -EFAULT) {
+ /* In this case we were trying to read something that wasn't on
+ * disk yet - return a page full of zeroes. This should be OK,
+ * because the object should be empty (if there was a write
+ * before this read, the read would be waiting with the page
+ * locked */
+ clear_highpage(page);
+
+ SetPageUptodate(page);
+ if (PageError(page))
+ ClearPageError(page);
+ ret = 0; /* recovered error */
+ EXOFS_DBGMSG("recovered read error\n");
+ } else /* Error */
+ SetPageError(page);
+
+ return ret;
+}
+
+static void update_write_page(struct page *page, int ret)
+{
+ if (ret) {
+ mapping_set_error(page->mapping, ret);
+ SetPageError(page);
+ }
+ end_page_writeback(page);
+}
+
+/* Called at the end of reads, to optionally unlock pages and update their
+ * status.
+ */
+static int __readpages_done(struct osd_request *or, struct page_collect *pcol,
+ bool do_unlock)
+{
+ struct bio_vec *bvec;
+ int i;
+ u64 resid;
+ u64 good_bytes;
+ u64 length = 0;
+ int ret = exofs_check_ok_resid(or, &resid, NULL);
+
+ osd_end_request(or);
+
+ if (likely(!ret))
+ good_bytes = pcol->length;
+ else if (!resid)
+ good_bytes = 0;
+ else
+ good_bytes = pcol->length - resid;
+
+ EXOFS_DBGMSG("readpages_done(0x%lx) good_bytes=0x%llx"
+ " length=0x%lx nr_pages=%u\n",
+ 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;
+ struct inode *inode = page->mapping->host;
+ int page_stat;
+
+ if (inode != pcol->inode)
+ continue; /* osd might add more pages at end */
+
+ if (likely(length < good_bytes))
+ page_stat = 0;
+ else
+ page_stat = ret;
+
+ EXOFS_DBGMSG(" readpages_done(0x%lx, 0x%lx) %s\n",
+ inode->i_ino, page->index,
+ page_stat ? "bad_bytes" : "good_bytes");
+
+ ret = update_read_page(page, page_stat);
+ if (do_unlock)
+ unlock_page(page);
+ length += bvec->bv_len;
+ }
+
+ pcol_free(pcol);
+ EXOFS_DBGMSG("readpages_done END\n");
+ return ret;
+}
+
+/* callback of async reads */
+static void readpages_done(struct osd_request *or, void *p)
+{
+ struct page_collect *pcol = p;
+
+ __readpages_done(or, pcol, true);
+ atomic_dec(&pcol->sbi->s_curr_pending);
+ kfree(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;
+
+ if (rw == READ)
+ update_read_page(page, ret);
+ else
+ update_write_page(page, ret);
+
+ unlock_page(page);
+ }
+ pcol_free(pcol);
+}
+
+static int read_exec(struct page_collect *pcol, bool is_sync)
+{
+ struct exofs_i_info *oi = exofs_i(pcol->inode);
+ struct osd_obj_id obj = {pcol->sbi->s_pid,
+ pcol->inode->i_ino + EXOFS_OBJ_OFF};
+ struct osd_request *or = NULL;
+ struct page_collect *pcol_copy = NULL;
+ loff_t i_start = pcol->pg_first << PAGE_CACHE_SHIFT;
+ int ret;
+
+ if (!pcol->bio)
+ return 0;
+
+ /* see comment in _readpage() about sync reads */
+ WARN_ON(is_sync && (pcol->nr_pages != 1));
+
+ or = osd_start_request(pcol->sbi->s_dev, GFP_KERNEL);
+ if (unlikely(!or)) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ osd_req_read(or, &obj, pcol->bio, i_start);
+
+ if (is_sync) {
+ exofs_sync_op(or, pcol->sbi->s_timeout, oi->i_cred);
+ return __readpages_done(or, pcol, false);
+ }
+
+ pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
+ if (!pcol_copy) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ *pcol_copy = *pcol;
+ ret = exofs_async_op(or, readpages_done, pcol_copy, oi->i_cred);
+ if (unlikely(ret))
+ goto err;
+
+ atomic_inc(&pcol->sbi->s_curr_pending);
+
+ EXOFS_DBGMSG("read_exec obj=0x%llx start=0x%llx length=0x%lx\n",
+ obj.id, _LLU(i_start), pcol->length);
+
+ /* pages ownership was passed to pcol_copy */
+ _pcol_reset(pcol);
+ return 0;
+
+err:
+ if (!is_sync)
+ _unlock_pcol_pages(pcol, ret, READ);
+ kfree(pcol_copy);
+ if (or)
+ osd_end_request(or);
+ return ret;
+}
+
+/* readpage_strip is called either directly from readpage() or by the VFS from
+ * within read_cache_pages(), to add one more page to be read. It will try to
+ * collect as many contiguous pages as posible. If a discontinuity is
+ * encountered, or it runs out of resources, it will submit the previous segment
+ * and will start a new collection. Eventually caller must submit the last
+ * segment if present.
+ */
+static int readpage_strip(void *data, struct page *page)
+{
+ struct page_collect *pcol = data;
+ struct inode *inode = pcol->inode;
+ struct exofs_i_info *oi = exofs_i(inode);
+ loff_t i_size = i_size_read(inode);
+ pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+ size_t len;
+ int ret;
+
+ /* FIXME: Just for debugging, will be removed */
+ if (PageUptodate(page))
+ EXOFS_ERR("PageUptodate(0x%lx, 0x%lx)\n", pcol->inode->i_ino,
+ page->index);
+
+ if (page->index < end_index)
+ len = PAGE_CACHE_SIZE;
+ else if (page->index == end_index)
+ len = i_size & ~PAGE_CACHE_MASK;
+ else
+ len = 0;
+
+ if (!len || !obj_created(oi)) {
+ /* this will be out of bounds, or doesn't exist yet.
+ * Current page is cleared and the request is split
+ */
+ clear_highpage(page);
+
+ SetPageUptodate(page);
+ if (PageError(page))
+ ClearPageError(page);
+
+ unlock_page(page);
+ EXOFS_DBGMSG("readpage_strip(0x%lx, 0x%lx) empty page,"
+ " splitting\n", inode->i_ino, page->index);
+
+ return read_exec(pcol, false);
+ }
+
+try_again:
+
+ if (unlikely(pcol->pg_first == -1)) {
+ pcol->pg_first = page->index;
+ } else if (unlikely((pcol->pg_first + pcol->nr_pages) !=
+ page->index)) {
+ /* Discontinuity detected, split the request */
+ ret = read_exec(pcol, false);
+ if (unlikely(ret))
+ goto fail;
+ goto try_again;
+ }
+
+ if (!pcol->bio) {
+ ret = pcol_try_alloc(pcol);
+ if (unlikely(ret))
+ goto fail;
+ }
+
+ if (len != PAGE_CACHE_SIZE)
+ zero_user(page, len, PAGE_CACHE_SIZE - len);
+
+ EXOFS_DBGMSG(" readpage_strip(0x%lx, 0x%lx) len=0x%zx\n",
+ inode->i_ino, page->index, len);
+
+ ret = pcol_add_page(pcol, page, len);
+ if (ret) {
+ EXOFS_DBGMSG("Failed pcol_add_page pages[i]=%p "
+ "this_len=0x%zx nr_pages=%u length=0x%lx\n",
+ page, len, pcol->nr_pages, pcol->length);
+
+ /* split the request, and start again with current page */
+ ret = read_exec(pcol, false);
+ if (unlikely(ret))
+ goto fail;
+
+ goto try_again;
+ }
+
+ return 0;
+
+fail:
+ /* SetPageError(page); ??? */
+ unlock_page(page);
+ return ret;
+}
+
+static int exofs_readpages(struct file *file, struct address_space *mapping,
+ struct list_head *pages, unsigned nr_pages)
+{
+ struct page_collect pcol;
+ int ret;
+
+ _pcol_init(&pcol, nr_pages, mapping->host);
+
+ ret = read_cache_pages(mapping, pages, readpage_strip, &pcol);
+ if (ret) {
+ EXOFS_ERR("read_cache_pages => %d\n", ret);
+ return ret;
+ }
+
+ return read_exec(&pcol, false);
+}
+
+static int _readpage(struct page *page, bool is_sync)
+{
+ struct page_collect pcol;
+ int ret;
+
+ _pcol_init(&pcol, 1, page->mapping->host);
+
+ /* readpage_strip might call read_exec(,async) inside at several places
+ * but this is safe for is_async=0 since read_exec will not do anything
+ * when we have a single page.
+ */
+ ret = readpage_strip(&pcol, page);
+ if (ret) {
+ EXOFS_ERR("_readpage => %d\n", ret);
+ return ret;
+ }
+
+ return read_exec(&pcol, is_sync);
+}
+
+/*
+ * We don't need the file
+ */
+static int exofs_readpage(struct file *file, struct page *page)
+{
+ return _readpage(page, false);
+}
+
+/* Callback for osd_write. All writes are asynchronouse */
+static void writepages_done(struct osd_request *or, void *p)
+{
+ struct page_collect *pcol = p;
+ struct bio_vec *bvec;
+ int i;
+ u64 resid;
+ u64 good_bytes;
+ u64 length = 0;
+
+ int ret = exofs_check_ok_resid(or, NULL, &resid);
+
+ osd_end_request(or);
+ atomic_dec(&pcol->sbi->s_curr_pending);
+
+ if (likely(!ret))
+ good_bytes = pcol->length;
+ else if (!resid)
+ good_bytes = 0;
+ else
+ good_bytes = pcol->length - resid;
+
+ EXOFS_DBGMSG("writepages_done(0x%lx) good_bytes=0x%llx"
+ " length=0x%lx nr_pages=%u\n",
+ 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;
+ struct inode *inode = page->mapping->host;
+ int page_stat;
+
+ if (inode != pcol->inode)
+ continue; /* osd might add more pages to a bio */
+
+ if (likely(length < good_bytes))
+ page_stat = 0;
+ else
+ page_stat = ret;
+
+ update_write_page(page, page_stat);
+ unlock_page(page);
+ EXOFS_DBGMSG(" writepages_done(0x%lx, 0x%lx) status=%d\n",
+ inode->i_ino, page->index, page_stat);
+
+ length += bvec->bv_len;
+ }
+
+ pcol_free(pcol);
+ kfree(pcol);
+ EXOFS_DBGMSG("writepages_done END\n");
+}
+
+static int write_exec(struct page_collect *pcol)
+{
+ struct exofs_i_info *oi = exofs_i(pcol->inode);
+ struct osd_obj_id obj = {pcol->sbi->s_pid,
+ pcol->inode->i_ino + EXOFS_OBJ_OFF};
+ struct osd_request *or = NULL;
+ struct page_collect *pcol_copy = NULL;
+ loff_t i_start = pcol->pg_first << PAGE_CACHE_SHIFT;
+ int ret;
+
+ if (!pcol->bio)
+ return 0;
+
+ or = osd_start_request(pcol->sbi->s_dev, GFP_KERNEL);
+ if (unlikely(!or)) {
+ EXOFS_ERR("write_exec: Faild to osd_start_request()\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
+ if (!pcol_copy) {
+ EXOFS_ERR("write_exec: Faild to kmalloc(pcol)\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ *pcol_copy = *pcol;
+
+ osd_req_write(or, &obj, pcol_copy->bio, i_start);
+ ret = exofs_async_op(or, writepages_done, pcol_copy, oi->i_cred);
+ if (unlikely(ret)) {
+ EXOFS_ERR("write_exec: exofs_async_op() Faild\n");
+ goto err;
+ }
+
+ atomic_inc(&pcol->sbi->s_curr_pending);
+ EXOFS_DBGMSG("write_exec(0x%lx, 0x%llx) start=0x%llx length=0x%lx\n",
+ pcol->inode->i_ino, pcol->pg_first, _LLU(i_start),
+ pcol->length);
+ /* pages ownership was passed to pcol_copy */
+ _pcol_reset(pcol);
+ return 0;
+
+err:
+ _unlock_pcol_pages(pcol, ret, WRITE);
+ kfree(pcol_copy);
+ if (or)
+ osd_end_request(or);
+ return ret;
+}
+
+/* writepage_strip is called either directly from writepage() or by the VFS from
+ * within write_cache_pages(), to add one more page to be written to storage.
+ * It will try to collect as many contiguous pages as possible. If a
+ * discontinuity is encountered or it runs out of resources it will submit the
+ * previous segment and will start a new collection.
+ * Eventually caller must submit the last segment if present.
+ */
+static int writepage_strip(struct page *page,
+ struct writeback_control *wbc_unused, void *data)
+{
+ struct page_collect *pcol = data;
+ struct inode *inode = pcol->inode;
+ struct exofs_i_info *oi = exofs_i(inode);
+ loff_t i_size = i_size_read(inode);
+ pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+ size_t len;
+ int ret;
+
+ BUG_ON(!PageLocked(page));
+
+ ret = wait_obj_created(oi);
+ if (unlikely(ret))
+ goto fail;
+
+ if (page->index < end_index)
+ /* in this case, the page is within the limits of the file */
+ len = PAGE_CACHE_SIZE;
+ else {
+ len = i_size & ~PAGE_CACHE_MASK;
+
+ if (page->index > end_index || !len) {
+ /* in this case, the page is outside the limits
+ * (truncate in progress)
+ */
+ ret = write_exec(pcol);
+ if (unlikely(ret))
+ goto fail;
+ if (PageError(page))
+ ClearPageError(page);
+ unlock_page(page);
+ return 0;
+ }
+ }
+
+try_again:
+
+ if (unlikely(pcol->pg_first == -1)) {
+ pcol->pg_first = page->index;
+ } else if (unlikely((pcol->pg_first + pcol->nr_pages) !=
+ page->index)) {
+ /* Discontinuity detected, split the request */
+ ret = write_exec(pcol);
+ if (unlikely(ret))
+ goto fail;
+ goto try_again;
+ }
+
+ if (!pcol->bio) {
+ ret = pcol_try_alloc(pcol);
+ if (unlikely(ret))
+ goto fail;
+ }
+
+ EXOFS_DBGMSG(" writepage_strip(0x%lx, 0x%lx) len=0x%zx\n",
+ inode->i_ino, page->index, len);
+
+ ret = pcol_add_page(pcol, page, len);
+ if (unlikely(ret)) {
+ EXOFS_DBGMSG("Failed pcol_add_page "
+ "nr_pages=%u total_length=0x%lx\n",
+ pcol->nr_pages, pcol->length);
+
+ /* split the request, next loop will start again */
+ ret = write_exec(pcol);
+ if (unlikely(ret)) {
+ EXOFS_DBGMSG("write_exec faild => %d", ret);
+ goto fail;
+ }
+
+ goto try_again;
+ }
+
+ BUG_ON(PageWriteback(page));
+ set_page_writeback(page);
+
+ return 0;
+
+fail:
+ set_bit(AS_EIO, &page->mapping->flags);
+ unlock_page(page);
+ return ret;
+}
+
+static int exofs_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ struct page_collect pcol;
+ long start, end, expected_pages;
+ int ret;
+
+ start = wbc->range_start >> PAGE_CACHE_SHIFT;
+ end = (wbc->range_end == LLONG_MAX) ?
+ start + mapping->nrpages :
+ wbc->range_end >> PAGE_CACHE_SHIFT;
+
+ if (start || end)
+ expected_pages = min(end - start + 1, 32L);
+ else
+ expected_pages = mapping->nrpages;
+
+ EXOFS_DBGMSG("inode(0x%lx) wbc->start=0x%llx wbc->end=0x%llx"
+ " m->nrpages=%lu start=0x%lx end=0x%lx\n",
+ mapping->host->i_ino, wbc->range_start, wbc->range_end,
+ mapping->nrpages, start, end);
+
+ _pcol_init(&pcol, expected_pages, mapping->host);
+
+ ret = write_cache_pages(mapping, wbc, writepage_strip, &pcol);
+ if (ret) {
+ EXOFS_ERR("write_cache_pages => %d\n", ret);
+ return ret;
+ }
+
+ return write_exec(&pcol);
+}
+
+static int exofs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct page_collect pcol;
+ int ret;
+
+ _pcol_init(&pcol, 1, page->mapping->host);
+
+ ret = writepage_strip(page, NULL, &pcol);
+ if (ret) {
+ EXOFS_ERR("exofs_writepage => %d\n", ret);
+ return ret;
+ }
+
+ return write_exec(&pcol);
+}
+
+int exofs_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata)
+{
+ int ret = 0;
+ struct page *page;
+
+ page = *pagep;
+ if (page == NULL) {
+ ret = simple_write_begin(file, mapping, pos, len, flags, pagep,
+ fsdata);
+ if (ret) {
+ EXOFS_DBGMSG("simple_write_begin faild\n");
+ return ret;
+ }
+
+ page = *pagep;
+ }
+
+ /* read modify write */
+ if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
+ ret = _readpage(page, true);
+ if (ret) {
+ /*SetPageError was done by _readpage. Is it ok?*/
+ unlock_page(page);
+ EXOFS_DBGMSG("__readpage_filler faild\n");
+ }
+ }
+
+ return ret;
+}
+
+static int exofs_write_begin_export(struct file *file,
+ struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata)
+{
+ *pagep = NULL;
+
+ return exofs_write_begin(file, mapping, pos, len, flags, pagep,
+ fsdata);
+}
+
+const struct address_space_operations exofs_aops = {
+ .readpage = exofs_readpage,
+ .readpages = exofs_readpages,
+ .writepage = exofs_writepage,
+ .writepages = exofs_writepages,
+ .write_begin = exofs_write_begin_export,
+ .write_end = simple_write_end,
+};
+
/******************************************************************************
* INODE OPERATIONS
*****************************************************************************/
--
1.6.2.1
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