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-rw-r--r--fs/ext4/inode.c169
1 files changed, 124 insertions, 45 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 24518b57733..ce47847bb37 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2003,11 +2003,15 @@ static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
handle_t *handle = NULL;
handle = ext4_journal_current_handle();
- BUG_ON(handle == NULL);
- BUG_ON(create == 0);
-
- ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
+ if (!handle) {
+ ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
+ bh_result, 0, 0, 0);
+ BUG_ON(!ret);
+ } else {
+ ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
bh_result, create, 0, EXT4_DELALLOC_RSVED);
+ }
+
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
@@ -2040,15 +2044,37 @@ static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
static int ext4_bh_unmapped_or_delay(handle_t *handle, struct buffer_head *bh)
{
- return !buffer_mapped(bh) || buffer_delay(bh);
+ /*
+ * unmapped buffer is possible for holes.
+ * delay buffer is possible with delayed allocation
+ */
+ return ((!buffer_mapped(bh) || buffer_delay(bh)) && buffer_dirty(bh));
+}
+
+static int ext4_normal_get_block_write(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ int ret = 0;
+ unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+
+ /*
+ * we don't want to do block allocation in writepage
+ * so call get_block_wrap with create = 0
+ */
+ ret = ext4_get_blocks_wrap(NULL, inode, iblock, max_blocks,
+ bh_result, 0, 0, 0);
+ if (ret > 0) {
+ bh_result->b_size = (ret << inode->i_blkbits);
+ ret = 0;
+ }
+ return ret;
}
/*
- * get called vi ext4_da_writepages after taking page lock
- * We may end up doing block allocation here in case
- * mpage_da_map_blocks failed to allocate blocks.
- *
- * We also get called via journal_submit_inode_data_buffers
+ * get called vi ext4_da_writepages after taking page lock (have journal handle)
+ * get called via journal_submit_inode_data_buffers (no journal handle)
+ * get called via shrink_page_list via pdflush (no journal handle)
+ * or grab_page_cache when doing write_begin (have journal handle)
*/
static int ext4_da_writepage(struct page *page,
struct writeback_control *wbc)
@@ -2056,37 +2082,61 @@ static int ext4_da_writepage(struct page *page,
int ret = 0;
loff_t size;
unsigned long len;
- handle_t *handle = NULL;
struct buffer_head *page_bufs;
struct inode *inode = page->mapping->host;
- handle = ext4_journal_current_handle();
- if (!handle) {
- /*
- * This can happen when we aren't called via
- * ext4_da_writepages() but directly (shrink_page_list).
- * We cannot easily start a transaction here so we just skip
- * writing the page in case we would have to do so.
- * We reach here also via journal_submit_inode_data_buffers
- */
- size = i_size_read(inode);
+ size = i_size_read(inode);
+ if (page->index == size >> PAGE_CACHE_SHIFT)
+ len = size & ~PAGE_CACHE_MASK;
+ else
+ len = PAGE_CACHE_SIZE;
+ if (page_has_buffers(page)) {
page_bufs = page_buffers(page);
- if (page->index == size >> PAGE_CACHE_SHIFT)
- len = size & ~PAGE_CACHE_MASK;
- else
- len = PAGE_CACHE_SIZE;
-
- if (walk_page_buffers(NULL, page_bufs, 0,
- len, NULL, ext4_bh_unmapped_or_delay)) {
+ if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
+ ext4_bh_unmapped_or_delay)) {
/*
- * We can't do block allocation under
- * page lock without a handle . So redirty
- * the page and return
+ * We don't want to do block allocation
+ * So redirty the page and return
* We may reach here when we do a journal commit
* via journal_submit_inode_data_buffers.
* If we don't have mapping block we just ignore
- * them
+ * them. We can also reach here via shrink_page_list
+ */
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ return 0;
+ }
+ } else {
+ /*
+ * The test for page_has_buffers() is subtle:
+ * We know the page is dirty but it lost buffers. That means
+ * that at some moment in time after write_begin()/write_end()
+ * has been called all buffers have been clean and thus they
+ * must have been written at least once. So they are all
+ * mapped and we can happily proceed with mapping them
+ * and writing the page.
+ *
+ * Try to initialize the buffer_heads and check whether
+ * all are mapped and non delay. We don't want to
+ * do block allocation here.
+ */
+ ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
+ ext4_normal_get_block_write);
+ if (!ret) {
+ page_bufs = page_buffers(page);
+ /* check whether all are mapped and non delay */
+ if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
+ ext4_bh_unmapped_or_delay)) {
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ return 0;
+ }
+ } else {
+ /*
+ * We can't do block allocation here
+ * so just redity the page and unlock
+ * and return
*/
redirty_page_for_writepage(wbc, page);
unlock_page(page);
@@ -2095,9 +2145,11 @@ static int ext4_da_writepage(struct page *page,
}
if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
- ret = nobh_writepage(page, ext4_da_get_block_write, wbc);
+ ret = nobh_writepage(page, ext4_normal_get_block_write, wbc);
else
- ret = block_write_full_page(page, ext4_da_get_block_write, wbc);
+ ret = block_write_full_page(page,
+ ext4_normal_get_block_write,
+ wbc);
return ret;
}
@@ -2438,12 +2490,14 @@ static int __ext4_normal_writepage(struct page *page,
struct inode *inode = page->mapping->host;
if (test_opt(inode->i_sb, NOBH))
- return nobh_writepage(page, ext4_get_block, wbc);
+ return nobh_writepage(page,
+ ext4_normal_get_block_write, wbc);
else
- return block_write_full_page(page, ext4_get_block, wbc);
+ return block_write_full_page(page,
+ ext4_normal_get_block_write,
+ wbc);
}
-
static int ext4_normal_writepage(struct page *page,
struct writeback_control *wbc)
{
@@ -2452,13 +2506,24 @@ static int ext4_normal_writepage(struct page *page,
loff_t len;
J_ASSERT(PageLocked(page));
- J_ASSERT(page_has_buffers(page));
if (page->index == size >> PAGE_CACHE_SHIFT)
len = size & ~PAGE_CACHE_MASK;
else
len = PAGE_CACHE_SIZE;
- BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
- ext4_bh_unmapped_or_delay));
+
+ if (page_has_buffers(page)) {
+ /* if page has buffers it should all be mapped
+ * and allocated. If there are not buffers attached
+ * to the page we know the page is dirty but it lost
+ * buffers. That means that at some moment in time
+ * after write_begin() / write_end() has been called
+ * all buffers have been clean and thus they must have been
+ * written at least once. So they are all mapped and we can
+ * happily proceed with mapping them and writing the page.
+ */
+ BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
+ ext4_bh_unmapped_or_delay));
+ }
if (!ext4_journal_current_handle())
return __ext4_normal_writepage(page, wbc);
@@ -2478,7 +2543,8 @@ static int __ext4_journalled_writepage(struct page *page,
int ret = 0;
int err;
- ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE, ext4_get_block);
+ ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
+ ext4_normal_get_block_write);
if (ret != 0)
goto out_unlock;
@@ -2525,13 +2591,24 @@ static int ext4_journalled_writepage(struct page *page,
loff_t len;
J_ASSERT(PageLocked(page));
- J_ASSERT(page_has_buffers(page));
if (page->index == size >> PAGE_CACHE_SHIFT)
len = size & ~PAGE_CACHE_MASK;
else
len = PAGE_CACHE_SIZE;
- BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
- ext4_bh_unmapped_or_delay));
+
+ if (page_has_buffers(page)) {
+ /* if page has buffers it should all be mapped
+ * and allocated. If there are not buffers attached
+ * to the page we know the page is dirty but it lost
+ * buffers. That means that at some moment in time
+ * after write_begin() / write_end() has been called
+ * all buffers have been clean and thus they must have been
+ * written at least once. So they are all mapped and we can
+ * happily proceed with mapping them and writing the page.
+ */
+ BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
+ ext4_bh_unmapped_or_delay));
+ }
if (ext4_journal_current_handle())
goto no_write;
@@ -2549,7 +2626,9 @@ static int ext4_journalled_writepage(struct page *page,
* really know unless we go poke around in the buffer_heads.
* But block_write_full_page will do the right thing.
*/
- return block_write_full_page(page, ext4_get_block, wbc);
+ return block_write_full_page(page,
+ ext4_normal_get_block_write,
+ wbc);
}
no_write:
redirty_page_for_writepage(wbc, page);
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-21 04:18:11 +0000