stapio:stp_main_loop:430 probe_start() returned 0
0xc016f24e : page_cache_sync_readahead+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f620 : __lru_cache_add+0x43/0x53 [kernel]
0xc016a23b : find_get_pages+0x8f/0xaf [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
page_cache_sync_readahead 0xc016f24e : page_cache_sync_readahead
+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f5fa : __lru_cache_add+0x1d/0x53 [kernel]
0xc016a276 : find_get_pages_contig+0x1b/0xc2 [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
page_cache_sync_readahead 0xc016f24e : page_cache_sync_readahead
+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f5fa : __lru_cache_add+0x1d/0x53 [kernel]
0xc016a276 : find_get_pages_contig+0x1b/0xc2 [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
page_cache_sync_readahead 0xc016f24e : page_cache_sync_readahead
+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f5fa : __lru_cache_add+0x1d/0x53 [kernel]
0xc016a276 : find_get_pages_contig+0x1b/0xc2 [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
page_cache_sync_readahead 0xc016f24e : page_cache_sync_readahead
+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f5fa : __lru_cache_add+0x1d/0x53 [kernel]
0xc016a276 : find_get_pages_contig+0x1b/0xc2 [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
page_cache_sync_readahead 0xc016f24e : page_cache_sync_readahead
+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f5fa : __lru_cache_add+0x1d/0x53 [kernel]
0xc016a276 : find_get_pages_contig+0x1b/0xc2 [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
page_cache_sync_readahead 0xc016f24e : page_cache_sync_readahead
+0x1/0x20 [kernel]
0xc016f58f : ____pagevec_lru_add+0x8d/0xdb [kernel]
0xc016f5fa : __lru_cache_add+0x1d/0x53 [kernel]
0xc016a276 : find_get_pages_contig+0x1b/0xc2 [kernel]
0xc018d007 : sys_sendfile+0x19/0x7d [kernel]
0xc018d7c8 : sys_write+0x1d/0x65 [kernel]
0xc018db3e : __fput+0xee/0x17a [kernel]
0xc0103b3f : ia32_sysenter_target+0x7b/0x124 [kernel]
===>: %s
/*
* A minimal readahead algorithm for trivial sequential/random reads.
*/
static unsigned long
ondemand_readahead(struct address_space *mapping,
struct file_ra_state *ra, struct file *filp,
bool hit_readahead_marker, pgoff_t offset,
unsigned long req_size)
{
int max = ra->ra_pages; /* max readahead pages */
pgoff_t prev_offset;
int sequential;
/*
* It's the expected callback offset, assume sequential access.
* Ramp up sizes, and push forward the readahead window.
*/
if (offset && (offset == (ra->start + ra->size - ra->async_size)
||
offset == (ra->start + ra->size))) {
ra->start += ra->size;
ra->size = get_next_ra_size(ra, max);
ra->async_size = ra->size;
goto readit;
}
prev_offset = ra->prev_pos >> PAGE_CACHE_SHIFT;
sequential = offset - prev_offset <= 1UL || req_size > max;
/*
* Standalone, small read.
* Read as is, and do not pollute the readahead state.
*/
if (!hit_readahead_marker && !sequential) {
return __do_page_cache_readahead(mapping, filp,
offset, req_size, 0);
}
/*
* Hit a marked page without valid readahead state.
* E.g. interleaved reads.
* Query the pagecache for async_size, which normally equals to
* readahead size. Ramp it up and use it as the new readahead
size.
*/
if (hit_readahead_marker) {
pgoff_t start;
rcu_read_lock();
start = radix_tree_next_hole(&mapping->page_tree,
offset,max+1);
rcu_read_unlock();
if (!start || start - offset > max)
return 0;
ra->start = start;
ra->size = start - offset; /* old async_size */
ra->size = get_next_ra_size(ra, max);
ra->async_size = ra->size;
goto readit;
}
/*
* It may be one of
* - first read on start of file
* - sequential cache miss
* - oversize random read
* Start readahead for it.
*/
ra->start = offset;
ra->size = get_init_ra_size(req_size, max);
ra->async_size = ra->size > req_size ? ra->size - req_size :
ra->size;
readit:
return ra_submit(ra, mapping, filp);
}
static int
__do_page_cache_readahead(struct address_space *mapping, struct file
*filp,
pgoff_t offset, unsigned long nr_to_read,
unsigned long lookahead_size)
{
struct inode *inode = mapping->host;
struct page *page;
unsigned long end_index; /* The last page we want to read
*/
LIST_HEAD(page_pool);
int page_idx;
int ret = 0;
loff_t isize = i_size_read(inode);
if (isize == 0)
goto out;
end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
/*
* Preallocate as many pages as we will need.
*/
for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
pgoff_t page_offset = offset + page_idx;
if (page_offset > end_index)
break;
rcu_read_lock();
page = radix_tree_lookup(&mapping->page_tree,
page_offset);
rcu_read_unlock();
if (page)
continue;
page = page_cache_alloc_cold(mapping);
if (!page)
break;
page->index = page_offset;
list_add(&page->lru, &page_pool);
if (page_idx == nr_to_read - lookahead_size)
SetPageReadahead(page);
ret++;
}
/*
* Now start the IO. We ignore I/O errors - if the page is not
* uptodate then the caller will launch readpage again, and
* will then handle the error.
*/
if (ret)
read_pages(mapping, filp, &page_pool, ret);
BUG_ON(!list_empty(&page_pool));
out:
return ret;
}
