#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
#include <linux/capability.h>
#include <linux/blkdev.h>
#include <linux/file.h>
#include <linux/bit_spinlock.h>
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
-static void invalidate_bh_lrus(void);
#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
}
/*
- * Default synchronous end-of-IO handler.. Just mark it up-to-date and
- * unlock the buffer. This is what ll_rw_block uses too.
+ * End-of-IO handler helper function which does not touch the bh after
+ * unlocking it.
+ * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
+ * a race there is benign: unlock_buffer() only use the bh's address for
+ * hashing after unlocking the buffer, so it doesn't actually touch the bh
+ * itself.
*/
-void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
+static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
{
if (uptodate) {
set_buffer_uptodate(bh);
clear_buffer_uptodate(bh);
}
unlock_buffer(bh);
+}
+
+/*
+ * Default synchronous end-of-IO handler.. Just mark it up-to-date and
+ * unlock the buffer. This is what ll_rw_block uses too.
+ */
+void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
+{
+ __end_buffer_read_notouch(bh, uptodate);
put_bh(bh);
}
we think the disk contains more recent information than the buffercache.
The update == 1 pass marks the buffers we need to update, the update == 2
pass does the actual I/O. */
-void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers)
+void invalidate_bdev(struct block_device *bdev)
{
struct address_space *mapping = bdev->bd_inode->i_mapping;
return;
invalidate_bh_lrus();
- /*
- * FIXME: what about destroy_dirty_buffers?
- * We really want to use invalidate_inode_pages2() for
- * that, but not until that's cleaned up.
- */
invalidate_mapping_pages(mapping, 0, -1);
}
for_each_online_pgdat(pgdat) {
zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones;
if (*zones)
- try_to_free_pages(zones, GFP_NOFS);
+ try_to_free_pages(zones, 0, GFP_NOFS);
}
}
}
EXPORT_SYMBOL(mark_buffer_dirty_inode);
+/*
+ * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
+ * dirty.
+ *
+ * If warn is true, then emit a warning if the page is not uptodate and has
+ * not been truncated.
+ */
+static int __set_page_dirty(struct page *page,
+ struct address_space *mapping, int warn)
+{
+ if (unlikely(!mapping))
+ return !TestSetPageDirty(page);
+
+ if (TestSetPageDirty(page))
+ return 0;
+
+ write_lock_irq(&mapping->tree_lock);
+ if (page->mapping) { /* Race with truncate? */
+ WARN_ON_ONCE(warn && !PageUptodate(page));
+
+ if (mapping_cap_account_dirty(mapping)) {
+ __inc_zone_page_state(page, NR_FILE_DIRTY);
+ __inc_bdi_stat(mapping->backing_dev_info,
+ BDI_RECLAIMABLE);
+ task_io_account_write(PAGE_CACHE_SIZE);
+ }
+ radix_tree_tag_set(&mapping->page_tree,
+ page_index(page), PAGECACHE_TAG_DIRTY);
+ }
+ write_unlock_irq(&mapping->tree_lock);
+ __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+
+ return 1;
+}
+
/*
* Add a page to the dirty page list.
*
*/
int __set_page_dirty_buffers(struct page *page)
{
- struct address_space * const mapping = page_mapping(page);
+ struct address_space *mapping = page_mapping(page);
if (unlikely(!mapping))
return !TestSetPageDirty(page);
}
spin_unlock(&mapping->private_lock);
- if (TestSetPageDirty(page))
- return 0;
-
- write_lock_irq(&mapping->tree_lock);
- if (page->mapping) { /* Race with truncate? */
- if (mapping_cap_account_dirty(mapping)) {
- __inc_zone_page_state(page, NR_FILE_DIRTY);
- task_io_account_write(PAGE_CACHE_SIZE);
- }
- radix_tree_tag_set(&mapping->page_tree,
- page_index(page), PAGECACHE_TAG_DIRTY);
- }
- write_unlock_irq(&mapping->tree_lock);
- __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
- return 1;
+ return __set_page_dirty(page, mapping, 1);
}
EXPORT_SYMBOL(__set_page_dirty_buffers);
struct page *page;
struct buffer_head *bh;
- page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
+ page = find_or_create_page(inode->i_mapping, index,
+ (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
if (!page)
return NULL;
/*
* Create buffers for the specified block device block's page. If
* that page was dirty, the buffers are set dirty also.
- *
- * Except that's a bug. Attaching dirty buffers to a dirty
- * blockdev's page can result in filesystem corruption, because
- * some of those buffers may be aliases of filesystem data.
- * grow_dev_page() will go BUG() if this happens.
*/
static int
grow_buffers(struct block_device *bdev, sector_t block, int size)
*/
void fastcall mark_buffer_dirty(struct buffer_head *bh)
{
+ WARN_ON_ONCE(!buffer_uptodate(bh));
if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
- __set_page_dirty_nobuffers(bh->b_page);
+ __set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0);
}
/*
put_cpu_var(bh_lrus);
}
-static void invalidate_bh_lrus(void)
+void invalidate_bh_lrus(void)
{
on_each_cpu(invalidate_bh_lru, NULL, 1, 1);
}
* The page and buffer_heads can be released at any time from
* here on.
*/
- wbc->pages_skipped++; /* We didn't write this page */
}
return err;
} while ((bh = bh->b_this_page) != head);
SetPageError(page);
BUG_ON(PageWriteback(page));
+ mapping_set_error(page->mapping, err);
set_page_writeback(page);
do {
struct buffer_head *next = bh->b_this_page;
goto done;
}
+/*
+ * If a page has any new buffers, zero them out here, and mark them uptodate
+ * and dirty so they'll be written out (in order to prevent uninitialised
+ * block data from leaking). And clear the new bit.
+ */
+void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
+{
+ unsigned int block_start, block_end;
+ struct buffer_head *head, *bh;
+
+ BUG_ON(!PageLocked(page));
+ if (!page_has_buffers(page))
+ return;
+
+ bh = head = page_buffers(page);
+ block_start = 0;
+ do {
+ block_end = block_start + bh->b_size;
+
+ if (buffer_new(bh)) {
+ if (block_end > from && block_start < to) {
+ if (!PageUptodate(page)) {
+ unsigned start, size;
+
+ start = max(from, block_start);
+ size = min(to, block_end) - start;
+
+ zero_user(page, start, size);
+ set_buffer_uptodate(bh);
+ }
+
+ clear_buffer_new(bh);
+ mark_buffer_dirty(bh);
+ }
+ }
+
+ block_start = block_end;
+ bh = bh->b_this_page;
+ } while (bh != head);
+}
+EXPORT_SYMBOL(page_zero_new_buffers);
+
static int __block_prepare_write(struct inode *inode, struct page *page,
unsigned from, unsigned to, get_block_t *get_block)
{
unmap_underlying_metadata(bh->b_bdev,
bh->b_blocknr);
if (PageUptodate(page)) {
+ clear_buffer_new(bh);
set_buffer_uptodate(bh);
+ mark_buffer_dirty(bh);
continue;
}
- if (block_end > to || block_start < from) {
- void *kaddr;
-
- kaddr = kmap_atomic(page, KM_USER0);
- if (block_end > to)
- memset(kaddr+to, 0,
- block_end-to);
- if (block_start < from)
- memset(kaddr+block_start,
- 0, from-block_start);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- }
+ if (block_end > to || block_start < from)
+ zero_user_segments(page,
+ to, block_end,
+ block_start, from);
continue;
}
}
if (!buffer_uptodate(*wait_bh))
err = -EIO;
}
- if (!err) {
- bh = head;
- do {
- if (buffer_new(bh))
- clear_buffer_new(bh);
- } while ((bh = bh->b_this_page) != head);
- return 0;
- }
- /* Error case: */
- /*
- * Zero out any newly allocated blocks to avoid exposing stale
- * data. If BH_New is set, we know that the block was newly
- * allocated in the above loop.
- */
- bh = head;
- block_start = 0;
- do {
- block_end = block_start+blocksize;
- if (block_end <= from)
- goto next_bh;
- if (block_start >= to)
- break;
- if (buffer_new(bh)) {
- void *kaddr;
-
- clear_buffer_new(bh);
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr+block_start, 0, bh->b_size);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- set_buffer_uptodate(bh);
- mark_buffer_dirty(bh);
- }
-next_bh:
- block_start = block_end;
- bh = bh->b_this_page;
- } while (bh != head);
+ if (unlikely(err))
+ page_zero_new_buffers(page, from, to);
return err;
}
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
}
+ clear_buffer_new(bh);
}
/*
return 0;
}
+/*
+ * block_write_begin takes care of the basic task of block allocation and
+ * bringing partial write blocks uptodate first.
+ *
+ * If *pagep is not NULL, then block_write_begin uses the locked page
+ * at *pagep rather than allocating its own. In this case, the page will
+ * not be unlocked or deallocated on failure.
+ */
+int block_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
+ get_block_t *get_block)
+{
+ struct inode *inode = mapping->host;
+ int status = 0;
+ struct page *page;
+ pgoff_t index;
+ unsigned start, end;
+ int ownpage = 0;
+
+ index = pos >> PAGE_CACHE_SHIFT;
+ start = pos & (PAGE_CACHE_SIZE - 1);
+ end = start + len;
+
+ page = *pagep;
+ if (page == NULL) {
+ ownpage = 1;
+ page = __grab_cache_page(mapping, index);
+ if (!page) {
+ status = -ENOMEM;
+ goto out;
+ }
+ *pagep = page;
+ } else
+ BUG_ON(!PageLocked(page));
+
+ status = __block_prepare_write(inode, page, start, end, get_block);
+ if (unlikely(status)) {
+ ClearPageUptodate(page);
+
+ if (ownpage) {
+ unlock_page(page);
+ page_cache_release(page);
+ *pagep = NULL;
+
+ /*
+ * prepare_write() may have instantiated a few blocks
+ * outside i_size. Trim these off again. Don't need
+ * i_size_read because we hold i_mutex.
+ */
+ if (pos + len > inode->i_size)
+ vmtruncate(inode, inode->i_size);
+ }
+ goto out;
+ }
+
+out:
+ return status;
+}
+EXPORT_SYMBOL(block_write_begin);
+
+int block_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ struct inode *inode = mapping->host;
+ unsigned start;
+
+ start = pos & (PAGE_CACHE_SIZE - 1);
+
+ if (unlikely(copied < len)) {
+ /*
+ * The buffers that were written will now be uptodate, so we
+ * don't have to worry about a readpage reading them and
+ * overwriting a partial write. However if we have encountered
+ * a short write and only partially written into a buffer, it
+ * will not be marked uptodate, so a readpage might come in and
+ * destroy our partial write.
+ *
+ * Do the simplest thing, and just treat any short write to a
+ * non uptodate page as a zero-length write, and force the
+ * caller to redo the whole thing.
+ */
+ if (!PageUptodate(page))
+ copied = 0;
+
+ page_zero_new_buffers(page, start+copied, start+len);
+ }
+ flush_dcache_page(page);
+
+ /* This could be a short (even 0-length) commit */
+ __block_commit_write(inode, page, start, start+copied);
+
+ return copied;
+}
+EXPORT_SYMBOL(block_write_end);
+
+int generic_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ struct inode *inode = mapping->host;
+
+ copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+ /*
+ * No need to use i_size_read() here, the i_size
+ * cannot change under us because we hold i_mutex.
+ *
+ * But it's important to update i_size while still holding page lock:
+ * page writeout could otherwise come in and zero beyond i_size.
+ */
+ if (pos+copied > inode->i_size) {
+ i_size_write(inode, pos+copied);
+ mark_inode_dirty(inode);
+ }
+
+ unlock_page(page);
+ page_cache_release(page);
+
+ return copied;
+}
+EXPORT_SYMBOL(generic_write_end);
+
/*
* Generic "read page" function for block devices that have the normal
* get_block functionality. This is most of the block device filesystems.
SetPageError(page);
}
if (!buffer_mapped(bh)) {
- void *kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + i * blocksize, 0, blocksize);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user(page, i * blocksize, blocksize);
if (!err)
set_buffer_uptodate(bh);
continue;
}
/* utility function for filesystems that need to do work on expanding
- * truncates. Uses prepare/commit_write to allow the filesystem to
+ * truncates. Uses filesystem pagecache writes to allow the filesystem to
* deal with the hole.
*/
-static int __generic_cont_expand(struct inode *inode, loff_t size,
- pgoff_t index, unsigned int offset)
+int generic_cont_expand_simple(struct inode *inode, loff_t size)
{
struct address_space *mapping = inode->i_mapping;
struct page *page;
+ void *fsdata;
unsigned long limit;
int err;
if (size > inode->i_sb->s_maxbytes)
goto out;
- err = -ENOMEM;
- page = grab_cache_page(mapping, index);
- if (!page)
- goto out;
- err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
- if (err) {
- /*
- * ->prepare_write() may have instantiated a few blocks
- * outside i_size. Trim these off again.
- */
- unlock_page(page);
- page_cache_release(page);
- vmtruncate(inode, inode->i_size);
+ err = pagecache_write_begin(NULL, mapping, size, 0,
+ AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
+ &page, &fsdata);
+ if (err)
goto out;
- }
- err = mapping->a_ops->commit_write(NULL, page, offset, offset);
+ err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
+ BUG_ON(err > 0);
- unlock_page(page);
- page_cache_release(page);
- if (err > 0)
- err = 0;
out:
return err;
}
-int generic_cont_expand(struct inode *inode, loff_t size)
+int cont_expand_zero(struct file *file, struct address_space *mapping,
+ loff_t pos, loff_t *bytes)
{
- pgoff_t index;
- unsigned int offset;
+ struct inode *inode = mapping->host;
+ unsigned blocksize = 1 << inode->i_blkbits;
+ struct page *page;
+ void *fsdata;
+ pgoff_t index, curidx;
+ loff_t curpos;
+ unsigned zerofrom, offset, len;
+ int err = 0;
- offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
+ index = pos >> PAGE_CACHE_SHIFT;
+ offset = pos & ~PAGE_CACHE_MASK;
- /* ugh. in prepare/commit_write, if from==to==start of block, we
- ** skip the prepare. make sure we never send an offset for the start
- ** of a block
- */
- if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
- /* caller must handle this extra byte. */
- offset++;
- }
- index = size >> PAGE_CACHE_SHIFT;
+ while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
+ zerofrom = curpos & ~PAGE_CACHE_MASK;
+ if (zerofrom & (blocksize-1)) {
+ *bytes |= (blocksize-1);
+ (*bytes)++;
+ }
+ len = PAGE_CACHE_SIZE - zerofrom;
- return __generic_cont_expand(inode, size, index, offset);
-}
+ err = pagecache_write_begin(file, mapping, curpos, len,
+ AOP_FLAG_UNINTERRUPTIBLE,
+ &page, &fsdata);
+ if (err)
+ goto out;
+ zero_user(page, zerofrom, len);
+ err = pagecache_write_end(file, mapping, curpos, len, len,
+ page, fsdata);
+ if (err < 0)
+ goto out;
+ BUG_ON(err != len);
+ err = 0;
+ }
-int generic_cont_expand_simple(struct inode *inode, loff_t size)
-{
- loff_t pos = size - 1;
- pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
+ /* page covers the boundary, find the boundary offset */
+ if (index == curidx) {
+ zerofrom = curpos & ~PAGE_CACHE_MASK;
+ /* if we will expand the thing last block will be filled */
+ if (offset <= zerofrom) {
+ goto out;
+ }
+ if (zerofrom & (blocksize-1)) {
+ *bytes |= (blocksize-1);
+ (*bytes)++;
+ }
+ len = offset - zerofrom;
- /* prepare/commit_write can handle even if from==to==start of block. */
- return __generic_cont_expand(inode, size, index, offset);
+ err = pagecache_write_begin(file, mapping, curpos, len,
+ AOP_FLAG_UNINTERRUPTIBLE,
+ &page, &fsdata);
+ if (err)
+ goto out;
+ zero_user(page, zerofrom, len);
+ err = pagecache_write_end(file, mapping, curpos, len, len,
+ page, fsdata);
+ if (err < 0)
+ goto out;
+ BUG_ON(err != len);
+ err = 0;
+ }
+out:
+ return err;
}
/*
* For moronic filesystems that do not allow holes in file.
* We may have to extend the file.
*/
-
-int cont_prepare_write(struct page *page, unsigned offset,
- unsigned to, get_block_t *get_block, loff_t *bytes)
+int cont_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
+ get_block_t *get_block, loff_t *bytes)
{
- struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
- struct page *new_page;
- pgoff_t pgpos;
- long status;
- unsigned zerofrom;
unsigned blocksize = 1 << inode->i_blkbits;
- void *kaddr;
-
- while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
- status = -ENOMEM;
- new_page = grab_cache_page(mapping, pgpos);
- if (!new_page)
- goto out;
- /* we might sleep */
- if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
- unlock_page(new_page);
- page_cache_release(new_page);
- continue;
- }
- zerofrom = *bytes & ~PAGE_CACHE_MASK;
- if (zerofrom & (blocksize-1)) {
- *bytes |= (blocksize-1);
- (*bytes)++;
- }
- status = __block_prepare_write(inode, new_page, zerofrom,
- PAGE_CACHE_SIZE, get_block);
- if (status)
- goto out_unmap;
- kaddr = kmap_atomic(new_page, KM_USER0);
- memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom);
- flush_dcache_page(new_page);
- kunmap_atomic(kaddr, KM_USER0);
- generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
- unlock_page(new_page);
- page_cache_release(new_page);
- }
-
- if (page->index < pgpos) {
- /* completely inside the area */
- zerofrom = offset;
- } else {
- /* page covers the boundary, find the boundary offset */
- zerofrom = *bytes & ~PAGE_CACHE_MASK;
+ unsigned zerofrom;
+ int err;
- /* if we will expand the thing last block will be filled */
- if (to > zerofrom && (zerofrom & (blocksize-1))) {
- *bytes |= (blocksize-1);
- (*bytes)++;
- }
+ err = cont_expand_zero(file, mapping, pos, bytes);
+ if (err)
+ goto out;
- /* starting below the boundary? Nothing to zero out */
- if (offset <= zerofrom)
- zerofrom = offset;
+ zerofrom = *bytes & ~PAGE_CACHE_MASK;
+ if (pos+len > *bytes && zerofrom & (blocksize-1)) {
+ *bytes |= (blocksize-1);
+ (*bytes)++;
}
- status = __block_prepare_write(inode, page, zerofrom, to, get_block);
- if (status)
- goto out1;
- if (zerofrom < offset) {
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr+zerofrom, 0, offset-zerofrom);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- __block_commit_write(inode, page, zerofrom, offset);
- }
- return 0;
-out1:
- ClearPageUptodate(page);
- return status;
-out_unmap:
- ClearPageUptodate(new_page);
- unlock_page(new_page);
- page_cache_release(new_page);
+ *pagep = NULL;
+ err = block_write_begin(file, mapping, pos, len,
+ flags, pagep, fsdata, get_block);
out:
- return status;
+ return err;
}
int block_prepare_write(struct page *page, unsigned from, unsigned to,
return 0;
}
+/*
+ * block_page_mkwrite() is not allowed to change the file size as it gets
+ * called from a page fault handler when a page is first dirtied. Hence we must
+ * be careful to check for EOF conditions here. We set the page up correctly
+ * for a written page which means we get ENOSPC checking when writing into
+ * holes and correct delalloc and unwritten extent mapping on filesystems that
+ * support these features.
+ *
+ * We are not allowed to take the i_mutex here so we have to play games to
+ * protect against truncate races as the page could now be beyond EOF. Because
+ * vmtruncate() writes the inode size before removing pages, once we have the
+ * page lock we can determine safely if the page is beyond EOF. If it is not
+ * beyond EOF, then the page is guaranteed safe against truncation until we
+ * unlock the page.
+ */
+int
+block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+ get_block_t get_block)
+{
+ struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+ unsigned long end;
+ loff_t size;
+ int ret = -EINVAL;
+
+ lock_page(page);
+ size = i_size_read(inode);
+ if ((page->mapping != inode->i_mapping) ||
+ (page_offset(page) > size)) {
+ /* page got truncated out from underneath us */
+ goto out_unlock;
+ }
+
+ /* page is wholly or partially inside EOF */
+ if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
+ end = size & ~PAGE_CACHE_MASK;
+ else
+ end = PAGE_CACHE_SIZE;
+
+ ret = block_prepare_write(page, 0, end, get_block);
+ if (!ret)
+ ret = block_commit_write(page, 0, end);
+
+out_unlock:
+ unlock_page(page);
+ return ret;
+}
/*
- * nobh_prepare_write()'s prereads are special: the buffer_heads are freed
+ * nobh_write_begin()'s prereads are special: the buffer_heads are freed
* immediately, while under the page lock. So it needs a special end_io
* handler which does not touch the bh after unlocking it.
- *
- * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
- * a race there is benign: unlock_buffer() only use the bh's address for
- * hashing after unlocking the buffer, so it doesn't actually touch the bh
- * itself.
*/
static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
{
- if (uptodate) {
- set_buffer_uptodate(bh);
- } else {
- /* This happens, due to failed READA attempts. */
- clear_buffer_uptodate(bh);
- }
- unlock_buffer(bh);
+ __end_buffer_read_notouch(bh, uptodate);
+}
+
+/*
+ * Attach the singly-linked list of buffers created by nobh_write_begin, to
+ * the page (converting it to circular linked list and taking care of page
+ * dirty races).
+ */
+static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
+{
+ struct buffer_head *bh;
+
+ BUG_ON(!PageLocked(page));
+
+ spin_lock(&page->mapping->private_lock);
+ bh = head;
+ do {
+ if (PageDirty(page))
+ set_buffer_dirty(bh);
+ if (!bh->b_this_page)
+ bh->b_this_page = head;
+ bh = bh->b_this_page;
+ } while (bh != head);
+ attach_page_buffers(page, head);
+ spin_unlock(&page->mapping->private_lock);
}
/*
* On entry, the page is fully not uptodate.
* On exit the page is fully uptodate in the areas outside (from,to)
*/
-int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
+int nobh_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
get_block_t *get_block)
{
- struct inode *inode = page->mapping->host;
+ struct inode *inode = mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocksize = 1 << blkbits;
- struct buffer_head map_bh;
- struct buffer_head *read_bh[MAX_BUF_PER_PAGE];
+ struct buffer_head *head, *bh;
+ struct page *page;
+ pgoff_t index;
+ unsigned from, to;
unsigned block_in_page;
- unsigned block_start;
+ unsigned block_start, block_end;
sector_t block_in_file;
- char *kaddr;
int nr_reads = 0;
- int i;
int ret = 0;
int is_mapped_to_disk = 1;
+ index = pos >> PAGE_CACHE_SHIFT;
+ from = pos & (PAGE_CACHE_SIZE - 1);
+ to = from + len;
+
+ page = __grab_cache_page(mapping, index);
+ if (!page)
+ return -ENOMEM;
+ *pagep = page;
+ *fsdata = NULL;
+
+ if (page_has_buffers(page)) {
+ unlock_page(page);
+ page_cache_release(page);
+ *pagep = NULL;
+ return block_write_begin(file, mapping, pos, len, flags, pagep,
+ fsdata, get_block);
+ }
+
if (PageMappedToDisk(page))
return 0;
+ /*
+ * Allocate buffers so that we can keep track of state, and potentially
+ * attach them to the page if an error occurs. In the common case of
+ * no error, they will just be freed again without ever being attached
+ * to the page (which is all OK, because we're under the page lock).
+ *
+ * Be careful: the buffer linked list is a NULL terminated one, rather
+ * than the circular one we're used to.
+ */
+ head = alloc_page_buffers(page, blocksize, 0);
+ if (!head) {
+ ret = -ENOMEM;
+ goto out_release;
+ }
+
block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
- map_bh.b_page = page;
/*
* We loop across all blocks in the page, whether or not they are
* part of the affected region. This is so we can discover if the
* page is fully mapped-to-disk.
*/
- for (block_start = 0, block_in_page = 0;
+ for (block_start = 0, block_in_page = 0, bh = head;
block_start < PAGE_CACHE_SIZE;
- block_in_page++, block_start += blocksize) {
- unsigned block_end = block_start + blocksize;
+ block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
int create;
- map_bh.b_state = 0;
+ block_end = block_start + blocksize;
+ bh->b_state = 0;
create = 1;
if (block_start >= to)
create = 0;
- map_bh.b_size = blocksize;
ret = get_block(inode, block_in_file + block_in_page,
- &map_bh, create);
+ bh, create);
if (ret)
goto failed;
- if (!buffer_mapped(&map_bh))
+ if (!buffer_mapped(bh))
is_mapped_to_disk = 0;
- if (buffer_new(&map_bh))
- unmap_underlying_metadata(map_bh.b_bdev,
- map_bh.b_blocknr);
- if (PageUptodate(page))
+ if (buffer_new(bh))
+ unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+ if (PageUptodate(page)) {
+ set_buffer_uptodate(bh);
continue;
- if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) {
- kaddr = kmap_atomic(page, KM_USER0);
- if (block_start < from)
- memset(kaddr+block_start, 0, from-block_start);
- if (block_end > to)
- memset(kaddr + to, 0, block_end - to);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ }
+ if (buffer_new(bh) || !buffer_mapped(bh)) {
+ zero_user_segments(page, block_start, from,
+ to, block_end);
continue;
}
- if (buffer_uptodate(&map_bh))
+ if (buffer_uptodate(bh))
continue; /* reiserfs does this */
if (block_start < from || block_end > to) {
- struct buffer_head *bh = alloc_buffer_head(GFP_NOFS);
-
- if (!bh) {
- ret = -ENOMEM;
- goto failed;
- }
- bh->b_state = map_bh.b_state;
- atomic_set(&bh->b_count, 0);
- bh->b_this_page = NULL;
- bh->b_page = page;
- bh->b_blocknr = map_bh.b_blocknr;
- bh->b_size = blocksize;
- bh->b_data = (char *)(long)block_start;
- bh->b_bdev = map_bh.b_bdev;
- bh->b_private = NULL;
- read_bh[nr_reads++] = bh;
+ lock_buffer(bh);
+ bh->b_end_io = end_buffer_read_nobh;
+ submit_bh(READ, bh);
+ nr_reads++;
}
}
if (nr_reads) {
- struct buffer_head *bh;
-
/*
* The page is locked, so these buffers are protected from
* any VM or truncate activity. Hence we don't need to care
* for the buffer_head refcounts.
*/
- for (i = 0; i < nr_reads; i++) {
- bh = read_bh[i];
- lock_buffer(bh);
- bh->b_end_io = end_buffer_read_nobh;
- submit_bh(READ, bh);
- }
- for (i = 0; i < nr_reads; i++) {
- bh = read_bh[i];
+ for (bh = head; bh; bh = bh->b_this_page) {
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
ret = -EIO;
- free_buffer_head(bh);
- read_bh[i] = NULL;
}
if (ret)
goto failed;
if (is_mapped_to_disk)
SetPageMappedToDisk(page);
+ *fsdata = head; /* to be released by nobh_write_end */
+
return 0;
failed:
- for (i = 0; i < nr_reads; i++) {
- if (read_bh[i])
- free_buffer_head(read_bh[i]);
- }
-
+ BUG_ON(!ret);
/*
- * Error recovery is pretty slack. Clear the page and mark it dirty
- * so we'll later zero out any blocks which _were_ allocated.
+ * Error recovery is a bit difficult. We need to zero out blocks that
+ * were newly allocated, and dirty them to ensure they get written out.
+ * Buffers need to be attached to the page at this point, otherwise
+ * the handling of potential IO errors during writeout would be hard
+ * (could try doing synchronous writeout, but what if that fails too?)
*/
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, PAGE_CACHE_SIZE);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- SetPageUptodate(page);
- set_page_dirty(page);
+ attach_nobh_buffers(page, head);
+ page_zero_new_buffers(page, from, to);
+
+out_release:
+ unlock_page(page);
+ page_cache_release(page);
+ *pagep = NULL;
+
+ if (pos + len > inode->i_size)
+ vmtruncate(inode, inode->i_size);
+
return ret;
}
-EXPORT_SYMBOL(nobh_prepare_write);
+EXPORT_SYMBOL(nobh_write_begin);
-/*
- * Make sure any changes to nobh_commit_write() are reflected in
- * nobh_truncate_page(), since it doesn't call commit_write().
- */
-int nobh_commit_write(struct file *file, struct page *page,
- unsigned from, unsigned to)
+int nobh_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
{
struct inode *inode = page->mapping->host;
- loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+ struct buffer_head *head = fsdata;
+ struct buffer_head *bh;
+
+ if (!PageMappedToDisk(page)) {
+ if (unlikely(copied < len) && !page_has_buffers(page))
+ attach_nobh_buffers(page, head);
+ if (page_has_buffers(page))
+ return generic_write_end(file, mapping, pos, len,
+ copied, page, fsdata);
+ }
SetPageUptodate(page);
set_page_dirty(page);
- if (pos > inode->i_size) {
- i_size_write(inode, pos);
+ if (pos+copied > inode->i_size) {
+ i_size_write(inode, pos+copied);
mark_inode_dirty(inode);
}
- return 0;
+
+ unlock_page(page);
+ page_cache_release(page);
+
+ while (head) {
+ bh = head;
+ head = head->b_this_page;
+ free_buffer_head(bh);
+ }
+
+ return copied;
}
-EXPORT_SYMBOL(nobh_commit_write);
+EXPORT_SYMBOL(nobh_write_end);
/*
* nobh_writepage() - based on block_full_write_page() except
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
- void *kaddr;
int ret;
/* Is the page fully inside i_size? */
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_segment(page, offset, PAGE_CACHE_SIZE);
out:
ret = mpage_writepage(page, get_block, wbc);
if (ret == -EAGAIN)
}
EXPORT_SYMBOL(nobh_writepage);
-/*
- * This function assumes that ->prepare_write() uses nobh_prepare_write().
- */
-int nobh_truncate_page(struct address_space *mapping, loff_t from)
+int nobh_truncate_page(struct address_space *mapping,
+ loff_t from, get_block_t *get_block)
{
- struct inode *inode = mapping->host;
- unsigned blocksize = 1 << inode->i_blkbits;
pgoff_t index = from >> PAGE_CACHE_SHIFT;
unsigned offset = from & (PAGE_CACHE_SIZE-1);
- unsigned to;
+ unsigned blocksize;
+ sector_t iblock;
+ unsigned length, pos;
+ struct inode *inode = mapping->host;
struct page *page;
- const struct address_space_operations *a_ops = mapping->a_ops;
- char *kaddr;
- int ret = 0;
+ struct buffer_head map_bh;
+ int err;
- if ((offset & (blocksize - 1)) == 0)
- goto out;
+ blocksize = 1 << inode->i_blkbits;
+ length = offset & (blocksize - 1);
+
+ /* Block boundary? Nothing to do */
+ if (!length)
+ return 0;
+
+ length = blocksize - length;
+ iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
- ret = -ENOMEM;
page = grab_cache_page(mapping, index);
+ err = -ENOMEM;
if (!page)
goto out;
- to = (offset + blocksize) & ~(blocksize - 1);
- ret = a_ops->prepare_write(NULL, page, offset, to);
- if (ret == 0) {
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- /*
- * It would be more correct to call aops->commit_write()
- * here, but this is more efficient.
- */
- SetPageUptodate(page);
- set_page_dirty(page);
+ if (page_has_buffers(page)) {
+has_buffers:
+ unlock_page(page);
+ page_cache_release(page);
+ return block_truncate_page(mapping, from, get_block);
}
+
+ /* Find the buffer that contains "offset" */
+ pos = blocksize;
+ while (offset >= pos) {
+ iblock++;
+ pos += blocksize;
+ }
+
+ err = get_block(inode, iblock, &map_bh, 0);
+ if (err)
+ goto unlock;
+ /* unmapped? It's a hole - nothing to do */
+ if (!buffer_mapped(&map_bh))
+ goto unlock;
+
+ /* Ok, it's mapped. Make sure it's up-to-date */
+ if (!PageUptodate(page)) {
+ err = mapping->a_ops->readpage(NULL, page);
+ if (err) {
+ page_cache_release(page);
+ goto out;
+ }
+ lock_page(page);
+ if (!PageUptodate(page)) {
+ err = -EIO;
+ goto unlock;
+ }
+ if (page_has_buffers(page))
+ goto has_buffers;
+ }
+ zero_user(page, offset, length);
+ set_page_dirty(page);
+ err = 0;
+
+unlock:
unlock_page(page);
page_cache_release(page);
out:
- return ret;
+ return err;
}
EXPORT_SYMBOL(nobh_truncate_page);
struct inode *inode = mapping->host;
struct page *page;
struct buffer_head *bh;
- void *kaddr;
int err;
blocksize = 1 << inode->i_blkbits;
goto unlock;
}
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, length);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
-
+ zero_user(page, offset, length);
mark_buffer_dirty(bh);
err = 0;
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
- void *kaddr;
/* Is the page fully inside i_size? */
if (page->index < end_index)
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_segment(page, offset, PAGE_CACHE_SIZE);
return __block_write_full_page(inode, page, get_block, wbc);
}
return tmp.b_blocknr;
}
-static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err)
+static void end_bio_bh_io_sync(struct bio *bio, int err)
{
struct buffer_head *bh = bio->bi_private;
- if (bio->bi_size)
- return 1;
-
if (err == -EOPNOTSUPP) {
set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
set_bit(BH_Eopnotsupp, &bh->b_state);
bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
bio_put(bio);
- return 0;
}
int submit_bh(int rw, struct buffer_head * bh)
struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
{
- struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags);
+ struct buffer_head *ret = kmem_cache_alloc(bh_cachep,
+ set_migrateflags(gfp_flags, __GFP_RECLAIMABLE));
if (ret) {
+ INIT_LIST_HEAD(&ret->b_assoc_buffers);
get_cpu_var(bh_accounting).nr++;
recalc_bh_state();
put_cpu_var(bh_accounting);
}
EXPORT_SYMBOL(free_buffer_head);
-static void
-init_buffer_head(void *data, struct kmem_cache *cachep, unsigned long flags)
-{
- if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
- SLAB_CTOR_CONSTRUCTOR) {
- struct buffer_head * bh = (struct buffer_head *)data;
-
- memset(bh, 0, sizeof(*bh));
- INIT_LIST_HEAD(&bh->b_assoc_buffers);
- }
-}
-
static void buffer_exit_cpu(int cpu)
{
int i;
static int buffer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
- if (action == CPU_DEAD)
+ if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
buffer_exit_cpu((unsigned long)hcpu);
return NOTIFY_OK;
}
+/**
+ * bh_uptodate_or_lock: Test whether the buffer is uptodate
+ * @bh: struct buffer_head
+ *
+ * Return true if the buffer is up-to-date and false,
+ * with the buffer locked, if not.
+ */
+int bh_uptodate_or_lock(struct buffer_head *bh)
+{
+ if (!buffer_uptodate(bh)) {
+ lock_buffer(bh);
+ if (!buffer_uptodate(bh))
+ return 0;
+ unlock_buffer(bh);
+ }
+ return 1;
+}
+EXPORT_SYMBOL(bh_uptodate_or_lock);
+
+/**
+ * bh_submit_read: Submit a locked buffer for reading
+ * @bh: struct buffer_head
+ *
+ * Returns zero on success and -EIO on error.
+ */
+int bh_submit_read(struct buffer_head *bh)
+{
+ BUG_ON(!buffer_locked(bh));
+
+ if (buffer_uptodate(bh)) {
+ unlock_buffer(bh);
+ return 0;
+ }
+
+ get_bh(bh);
+ bh->b_end_io = end_buffer_read_sync;
+ submit_bh(READ, bh);
+ wait_on_buffer(bh);
+ if (buffer_uptodate(bh))
+ return 0;
+ return -EIO;
+}
+EXPORT_SYMBOL(bh_submit_read);
+
+static void
+init_buffer_head(struct kmem_cache *cachep, void *data)
+{
+ struct buffer_head *bh = data;
+
+ memset(bh, 0, sizeof(*bh));
+ INIT_LIST_HEAD(&bh->b_assoc_buffers);
+}
+
void __init buffer_init(void)
{
int nrpages;
bh_cachep = kmem_cache_create("buffer_head",
- sizeof(struct buffer_head), 0,
- (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
- SLAB_MEM_SPREAD),
- init_buffer_head,
- NULL);
+ sizeof(struct buffer_head), 0,
+ (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
+ SLAB_MEM_SPREAD),
+ init_buffer_head);
/*
* Limit the bh occupancy to 10% of ZONE_NORMAL
EXPORT_SYMBOL(__wait_on_buffer);
EXPORT_SYMBOL(block_commit_write);
EXPORT_SYMBOL(block_prepare_write);
+EXPORT_SYMBOL(block_page_mkwrite);
EXPORT_SYMBOL(block_read_full_page);
EXPORT_SYMBOL(block_sync_page);
EXPORT_SYMBOL(block_truncate_page);
EXPORT_SYMBOL(block_write_full_page);
-EXPORT_SYMBOL(cont_prepare_write);
+EXPORT_SYMBOL(cont_write_begin);
EXPORT_SYMBOL(end_buffer_read_sync);
EXPORT_SYMBOL(end_buffer_write_sync);
EXPORT_SYMBOL(file_fsync);
EXPORT_SYMBOL(fsync_bdev);
EXPORT_SYMBOL(generic_block_bmap);
EXPORT_SYMBOL(generic_commit_write);
-EXPORT_SYMBOL(generic_cont_expand);
EXPORT_SYMBOL(generic_cont_expand_simple);
EXPORT_SYMBOL(init_buffer);
EXPORT_SYMBOL(invalidate_bdev);