Just FYI (I'll resend for -mm after the last conversions get in), this shows
how much cruft we shed after the old aops go away...
Index: linux-2.6/drivers/block/loop.c
===================================================================
--- linux-2.6.orig/drivers/block/loop.c
+++ linux-2.6/drivers/block/loop.c
@@ -40,8 +40,7 @@
* Heinz Mauelshagen <mge@xxxxxxxxxxx>, Feb 2002
*
* Support for falling back on the write file operation when the address space
- * operations prepare_write and/or commit_write are not available on the
- * backing filesystem.
+ * operations write_begin is not available on the backing filesystem.
* Anton Altaparmakov, 16 Feb 2005
*
* Still To Fix:
@@ -766,7 +765,7 @@ static int loop_set_fd(struct loop_devic
*/
if (!file->f_op->splice_read)
goto out_putf;
- if (aops->prepare_write || aops->write_begin)
+ if (aops->write_begin)
lo_flags |= LO_FLAGS_USE_AOPS;
if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
lo_flags |= LO_FLAGS_READ_ONLY;
Index: linux-2.6/fs/fat/inode.c
===================================================================
--- linux-2.6.orig/fs/fat/inode.c
+++ linux-2.6/fs/fat/inode.c
@@ -175,7 +175,7 @@ static ssize_t fat_direct_IO(int rw, str
if (rw == WRITE) {
/*
- * FIXME: blockdev_direct_IO() doesn't use ->prepare_write(),
+ * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
* so we need to update the ->mmu_private to block boundary.
*
* But we must fill the remaining area or hole by nul for
Index: linux-2.6/fs/ocfs2/file.c
===================================================================
--- linux-2.6.orig/fs/ocfs2/file.c
+++ linux-2.6/fs/ocfs2/file.c
@@ -837,8 +837,7 @@ leave:
/* Some parts of this taken from generic_cont_expand, which turned out
* to be too fragile to do exactly what we need without us having to
- * worry about recursive locking in ->prepare_write() and
- * ->commit_write(). */
+ * worry about recursive locking in ->write_begin() and ->write_end(). */
static int ocfs2_write_zero_page(struct inode *inode,
u64 size)
{
Index: linux-2.6/fs/splice.c
===================================================================
--- linux-2.6.orig/fs/splice.c
+++ linux-2.6/fs/splice.c
@@ -731,8 +731,8 @@ ssize_t splice_from_pipe(struct pipe_ino
};
/*
- * The actor worker might be calling ->prepare_write and
- * ->commit_write. Most of the time, these expect i_mutex to
+ * The actor worker might be calling ->write_begin and
+ * ->write_end. Most of the time, these expect i_mutex to
* be held. Since this may result in an ABBA deadlock with
* pipe->inode, we have to order lock acquiry here.
*/
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -479,13 +479,6 @@ struct address_space_operations {
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
- /*
- * ext3 requires that a successful prepare_write() call be followed
- * by a commit_write() call - they must be balanced
- */
- int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
- int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
-
int (*write_begin)(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata);
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -2016,48 +2016,8 @@ int pagecache_write_begin(struct file *f
{
const struct address_space_operations *aops = mapping->a_ops;
- if (aops->write_begin) {
- return aops->write_begin(file, mapping, pos, len, flags,
+ return aops->write_begin(file, mapping, pos, len, flags,
pagep, fsdata);
- } else {
- int ret;
- pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
- struct inode *inode = mapping->host;
- struct page *page;
-again:
- page = __grab_cache_page(mapping, index);
- *pagep = page;
- if (!page)
- return -ENOMEM;
-
- if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
- /*
- * There is no way to resolve a short write situation
- * for a !Uptodate page (except by double copying in
- * the caller done by generic_perform_write_2copy).
- *
- * Instead, we have to bring it uptodate here.
- */
- ret = aops->readpage(file, page);
- page_cache_release(page);
- if (ret) {
- if (ret == AOP_TRUNCATED_PAGE)
- goto again;
- return ret;
- }
- goto again;
- }
-
- ret = aops->prepare_write(file, page, offset, offset+len);
- if (ret) {
- unlock_page(page);
- page_cache_release(page);
- if (pos + len > inode->i_size)
- vmtruncate(inode, inode->i_size);
- }
- return ret;
- }
}
EXPORT_SYMBOL(pagecache_write_begin);
@@ -2068,28 +2028,8 @@ int pagecache_write_end(struct file *fil
const struct address_space_operations *aops = mapping->a_ops;
int ret;
- if (aops->write_end) {
- mark_page_accessed(page);
- ret = aops->write_end(file, mapping, pos, len, copied,
- page, fsdata);
- } else {
- unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
- struct inode *inode = mapping->host;
-
- flush_dcache_page(page);
- ret = aops->commit_write(file, page, offset, offset+len);
- unlock_page(page);
- mark_page_accessed(page);
- page_cache_release(page);
-
- if (ret < 0) {
- if (pos + len > inode->i_size)
- vmtruncate(inode, inode->i_size);
- } else if (ret > 0)
- ret = min_t(size_t, copied, ret);
- else
- ret = copied;
- }
+ mark_page_accessed(page);
+ ret = aops->write_end(file, mapping, pos, len, copied, page, fsdata);
return ret;
}
@@ -2213,174 +2153,6 @@ repeat:
}
EXPORT_SYMBOL(__grab_cache_page);
-static ssize_t generic_perform_write_2copy(struct file *file,
- struct iov_iter *i, loff_t pos)
-{
- struct address_space *mapping = file->f_mapping;
- const struct address_space_operations *a_ops = mapping->a_ops;
- struct inode *inode = mapping->host;
- long status = 0;
- ssize_t written = 0;
-
- do {
- struct page *src_page;
- struct page *page;
- pgoff_t index; /* Pagecache index for current page */
- unsigned long offset; /* Offset into pagecache page */
- unsigned long bytes; /* Bytes to write to page */
- size_t copied; /* Bytes copied from user */
-
- offset = (pos & (PAGE_CACHE_SIZE - 1));
- index = pos >> PAGE_CACHE_SHIFT;
- bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
- iov_iter_count(i));
-
- /*
- * a non-NULL src_page indicates that we're doing the
- * copy via get_user_pages and kmap.
- */
- src_page = NULL;
-
- /*
- * Bring in the user page that we will copy from _first_.
- * Otherwise there's a nasty deadlock on copying from the
- * same page as we're writing to, without it being marked
- * up-to-date.
- *
- * Not only is this an optimisation, but it is also required
- * to check that the address is actually valid, when atomic
- * usercopies are used, below.
- */
- if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
- status = -EFAULT;
- break;
- }
-
- page = __grab_cache_page(mapping, index);
- if (!page) {
- status = -ENOMEM;
- break;
- }
-
- /*
- * non-uptodate pages cannot cope with short copies, and we
- * cannot take a pagefault with the destination page locked.
- * So pin the source page to copy it.
- */
- if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
- unlock_page(page);
-
- src_page = alloc_page(GFP_KERNEL);
- if (!src_page) {
- page_cache_release(page);
- status = -ENOMEM;
- break;
- }
-
- /*
- * Cannot get_user_pages with a page locked for the
- * same reason as we can't take a page fault with a
- * page locked (as explained below).
- */
- copied = iov_iter_copy_from_user(src_page, i,
- offset, bytes);
- if (unlikely(copied == 0)) {
- status = -EFAULT;
- page_cache_release(page);
- page_cache_release(src_page);
- break;
- }
- bytes = copied;
-
- lock_page(page);
- /*
- * Can't handle the page going uptodate here, because
- * that means we would use non-atomic usercopies, which
- * zero out the tail of the page, which can cause
- * zeroes to become transiently visible. We could just
- * use a non-zeroing copy, but the APIs aren't too
- * consistent.
- */
- if (unlikely(!page->mapping || PageUptodate(page))) {
- unlock_page(page);
- page_cache_release(page);
- page_cache_release(src_page);
- continue;
- }
- }
-
- status = a_ops->prepare_write(file, page, offset, offset+bytes);
- if (unlikely(status))
- goto fs_write_aop_error;
-
- if (!src_page) {
- /*
- * Must not enter the pagefault handler here, because
- * we hold the page lock, so we might recursively
- * deadlock on the same lock, or get an ABBA deadlock
- * against a different lock, or against the mmap_sem
- * (which nests outside the page lock). So increment
- * preempt count, and use _atomic usercopies.
- *
- * The page is uptodate so we are OK to encounter a
- * short copy: if unmodified parts of the page are
- * marked dirty and written out to disk, it doesn't
- * really matter.
- */
- pagefault_disable();
- copied = iov_iter_copy_from_user_atomic(page, i,
- offset, bytes);
- pagefault_enable();
- } else {
- void *src, *dst;
- src = kmap_atomic(src_page, KM_USER0);
- dst = kmap_atomic(page, KM_USER1);
- memcpy(dst + offset, src + offset, bytes);
- kunmap_atomic(dst, KM_USER1);
- kunmap_atomic(src, KM_USER0);
- copied = bytes;
- }
- flush_dcache_page(page);
-
- status = a_ops->commit_write(file, page, offset, offset+bytes);
- if (unlikely(status < 0))
- goto fs_write_aop_error;
- if (unlikely(status > 0)) /* filesystem did partial write */
- copied = min_t(size_t, copied, status);
-
- unlock_page(page);
- mark_page_accessed(page);
- page_cache_release(page);
- if (src_page)
- page_cache_release(src_page);
-
- iov_iter_advance(i, copied);
- pos += copied;
- written += copied;
-
- balance_dirty_pages_ratelimited(mapping);
- cond_resched();
- continue;
-
-fs_write_aop_error:
- unlock_page(page);
- page_cache_release(page);
- if (src_page)
- page_cache_release(src_page);
-
- /*
- * 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 + bytes > inode->i_size)
- vmtruncate(inode, inode->i_size);
- break;
- } while (iov_iter_count(i));
-
- return written ? written : status;
-}
-
static ssize_t generic_perform_write(struct file *file,
struct iov_iter *i, loff_t pos)
{
@@ -2481,10 +2253,7 @@ generic_file_buffered_write(struct kiocb
struct iov_iter i;
iov_iter_init(&i, iov, nr_segs, count, written);
- if (a_ops->write_begin)
- status = generic_perform_write(file, &i, pos);
- else
- status = generic_perform_write_2copy(file, &i, pos);
+ status = generic_perform_write(file, &i, pos);
if (likely(status >= 0)) {
written += status;
Index: linux-2.6/Documentation/filesystems/Locking
===================================================================
--- linux-2.6.orig/Documentation/filesystems/Locking
+++ linux-2.6/Documentation/filesystems/Locking
@@ -161,8 +161,12 @@ prototypes:
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
- int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
- int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
+ int (*write_begin)(struct file *, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata);
+ int (*write_end)(struct file *, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata);
sector_t (*bmap)(struct address_space *, sector_t);
int (*invalidatepage) (struct page *, unsigned long);
int (*releasepage) (struct page *, int);
@@ -180,8 +184,6 @@ sync_page: no maybe
writepages: no
set_page_dirty no no
readpages: no
-prepare_write: no yes yes
-commit_write: no yes yes
write_begin: no locks the page yes
write_end: no yes, unlocks yes
perform_write: no n/a yes
@@ -191,7 +193,7 @@ releasepage: no yes
direct_IO: no
launder_page: no yes
- ->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
+ ->write_begin(), ->write_end(), ->sync_page() and ->readpage()
may be called from the request handler (/dev/loop).
->readpage() unlocks the page, either synchronously or via I/O
Index: linux-2.6/Documentation/filesystems/vfs.txt
===================================================================
--- linux-2.6.orig/Documentation/filesystems/vfs.txt
+++ linux-2.6/Documentation/filesystems/vfs.txt
@@ -492,7 +492,7 @@ written-back to storage typically in who
address_space has finer control of write sizes.
The read process essentially only requires 'readpage'. The write
-process is more complicated and uses prepare_write/commit_write or
+process is more complicated and uses write_begin/write_end or
set_page_dirty to write data into the address_space, and writepage,
sync_page, and writepages to writeback data to storage.
@@ -521,8 +521,6 @@ struct address_space_operations {
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
- int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
- int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
int (*write_begin)(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata);
@@ -598,37 +596,7 @@ struct address_space_operations {
readpages is only used for read-ahead, so read errors are
ignored. If anything goes wrong, feel free to give up.
- prepare_write: called by the generic write path in VM to set up a write
- request for a page. This indicates to the address space that
- the given range of bytes is about to be written. The
- address_space should check that the write will be able to
- complete, by allocating space if necessary and doing any other
- internal housekeeping. If the write will update parts of
- any basic-blocks on storage, then those blocks should be
- pre-read (if they haven't been read already) so that the
- updated blocks can be written out properly.
- The page will be locked.
-
- Note: the page _must not_ be marked uptodate in this function
- (or anywhere else) unless it actually is uptodate right now. As
- soon as a page is marked uptodate, it is possible for a concurrent
- read(2) to copy it to userspace.
-
- commit_write: If prepare_write succeeds, new data will be copied
- into the page and then commit_write will be called. It will
- typically update the size of the file (if appropriate) and
- mark the inode as dirty, and do any other related housekeeping
- operations. It should avoid returning an error if possible -
- errors should have been handled by prepare_write.
-
- write_begin: This is intended as a replacement for prepare_write. The
- key differences being that:
- - it returns a locked page (in *pagep) rather than being
- given a pre locked page;
- - it must be able to cope with short writes (where the
- length passed to write_begin is greater than the number
- of bytes copied into the page).
-
+ write_begin:
Called by the generic buffered write code to ask the filesystem to
prepare to write len bytes at the given offset in the file. The
address_space should check that the write will be able to complete,
@@ -640,6 +608,9 @@ struct address_space_operations {
The filesystem must return the locked pagecache page for the specified
offset, in *pagep, for the caller to write into.
+ It must be able to cope with short writes (where the length passed to
+ write_begin is greater than the number of bytes copied into the page).
+
flags is a field for AOP_FLAG_xxx flags, described in
include/linux/fs.h.
--
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