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Btrfs: Do metadata checksums for reads via a workqueue

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Before, metadata checksumming was done by the callers of read_tree_block,
which would set EXTENT_CSUM bits in the extent tree to show that a given
range of pages was already checksummed and didn't need to be verified
again.

But, those bits could go away via try_to_releasepage, and the end
result was bogus checksum failures on pages that never left the cache.

The new code validates checksums when the page is read.  It is a little
tricky because metadata blocks can span pages and a single read may
end up going via multiple bios.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2008-04-09 16:28:12 -04:00
parent 728131d8e4
commit ce9adaa5a7
7 changed files with 310 additions and 67 deletions
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100
fs/btrfs/extent_io.c
View File

@@ -2592,6 +2592,22 @@ static inline struct page *extent_buffer_page(struct extent_buffer *eb,
return p;
}
int release_extent_buffer_tail_pages(struct extent_buffer *eb)
{
unsigned long num_pages = num_extent_pages(eb->start, eb->len);
struct page *page;
unsigned long i;
if (num_pages == 1)
return 0;
for (i = 1; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
page_cache_release(page);
}
return 0;
}
int invalidate_extent_lru(struct extent_io_tree *tree, u64 start,
unsigned long len)
{
@@ -2609,9 +2625,6 @@ int invalidate_extent_lru(struct extent_io_tree *tree, u64 start,
if (eb->start <= start && eb->start + eb->len > start) {
eb->flags &= ~EXTENT_UPTODATE;
}
if (eb->start == start) {
eb->flags &= ~EXTENT_CSUM;
}
cur = cur->next;
} while (cur != lru);
out:
@@ -2682,7 +2695,6 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
page_cache_get(page0);
mark_page_accessed(page0);
set_page_extent_mapped(page0);
WARN_ON(!PageUptodate(page0));
set_page_extent_head(page0, len);
} else {
i = 0;
@@ -2933,13 +2945,39 @@ int set_extent_buffer_uptodate(struct extent_io_tree *tree,
}
EXPORT_SYMBOL(set_extent_buffer_uptodate);
int extent_range_uptodate(struct extent_io_tree *tree,
u64 start, u64 end)
{
struct page *page;
int ret;
int pg_uptodate = 1;
int uptodate;
unsigned long index;
ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1);
if (ret)
return 1;
while(start <= end) {
index = start >> PAGE_CACHE_SHIFT;
page = find_get_page(tree->mapping, index);
uptodate = PageUptodate(page);
page_cache_release(page);
if (!uptodate) {
pg_uptodate = 0;
break;
}
start += PAGE_CACHE_SIZE;
}
return pg_uptodate;
}
int extent_buffer_uptodate(struct extent_io_tree *tree,
struct extent_buffer *eb)
struct extent_buffer *eb)
{
int ret = 0;
int ret2;
int num_pages;
int i;
unsigned long num_pages;
unsigned long i;
struct page *page;
int pg_uptodate = 1;
@@ -2975,13 +3013,16 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
struct page *page;
int err;
int ret = 0;
int locked_pages = 0;
int all_uptodate = 1;
int inc_all_pages = 0;
unsigned long num_pages;
struct bio *bio = NULL;
if (eb->flags & EXTENT_UPTODATE)
return 0;
if (0 && test_range_bit(tree, eb->start, eb->start + eb->len - 1,
if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
EXTENT_UPTODATE, 1)) {
return 0;
}
@@ -2997,17 +3038,30 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
num_pages = num_extent_pages(eb->start, eb->len);
for (i = start_i; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
if (PageUptodate(page)) {
continue;
}
if (!wait) {
if (TestSetPageLocked(page)) {
continue;
}
if (TestSetPageLocked(page))
goto unlock_exit;
} else {
lock_page(page);
}
locked_pages++;
if (!PageUptodate(page)) {
all_uptodate = 0;
}
}
if (all_uptodate) {
if (start_i == 0)
eb->flags |= EXTENT_UPTODATE;
goto unlock_exit;
}
for (i = start_i; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
if (inc_all_pages)
page_cache_get(page);
if (!PageUptodate(page)) {
if (start_i == 0)
inc_all_pages = 1;
err = __extent_read_full_page(tree, page,
get_extent, &bio);
if (err) {
@@ -3034,6 +3088,16 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
if (!ret)
eb->flags |= EXTENT_UPTODATE;
return ret;
unlock_exit:
i = start_i;
while(locked_pages > 0) {
page = extent_buffer_page(eb, i);
i++;
unlock_page(page);
locked_pages--;
}
return ret;
}
EXPORT_SYMBOL(read_extent_buffer_pages);
@@ -3048,7 +3112,6 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
char *dst = (char *)dstv;
size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
unsigned long num_pages = num_extent_pages(eb->start, eb->len);
WARN_ON(start > eb->len);
WARN_ON(start + len > eb->start + eb->len);
@@ -3057,11 +3120,6 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
while(len > 0) {
page = extent_buffer_page(eb, i);
if (!PageUptodate(page)) {
printk("page %lu not up to date i %lu, total %lu, len %lu\n", page->index, i, num_pages, eb->len);
WARN_ON(1);
}
WARN_ON(!PageUptodate(page));
cur = min(len, (PAGE_CACHE_SIZE - offset));
kaddr = kmap_atomic(page, KM_USER1);
@@ -3105,7 +3163,6 @@ printk("bad mapping eb start %Lu len %lu, wanted %lu %lu\n", eb->start, eb->len,
}
p = extent_buffer_page(eb, i);
WARN_ON(!PageUptodate(p));
kaddr = kmap_atomic(p, km);
*token = kaddr;
*map = kaddr + offset;
@@ -3165,7 +3222,6 @@ int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
while(len > 0) {
page = extent_buffer_page(eb, i);
WARN_ON(!PageUptodate(page));
cur = min(len, (PAGE_CACHE_SIZE - offset));