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Message-ID: <20080510183956.GA14315@lst.de>
Date: Sat, 10 May 2008 20:39:56 +0200
From: Christoph Hellwig <hch@....de>
To: akpm@...l.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] kill generic_file_direct_IO
generic_file_direct_IO is a common helper around the invocation of
->direct_IO. But there's almost nothing to shared between the read
and write side, so we're better off without this helper.
Signed-off-by: Christoph Hellwig <hch@....de>
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c 2008-04-29 08:35:05.000000000 +0200
+++ linux-2.6/mm/filemap.c 2008-05-05 09:29:57.000000000 +0200
@@ -42,9 +42,6 @@
#include <asm/mman.h>
-static ssize_t
-generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
- loff_t offset, unsigned long nr_segs);
/*
* Shared mappings implemented 30.11.1994. It's not fully working yet,
@@ -1204,8 +1201,11 @@ generic_file_aio_read(struct kiocb *iocb
goto out; /* skip atime */
size = i_size_read(inode);
if (pos < size) {
- retval = generic_file_direct_IO(READ, iocb,
- iov, pos, nr_segs);
+ retval = filemap_write_and_wait(mapping);
+ if (!retval) {
+ retval = mapping->a_ops->direct_IO(READ, iocb,
+ iov, pos, nr_segs);
+ }
if (retval > 0)
*ppos = pos + retval;
}
@@ -1998,11 +1998,55 @@ generic_file_direct_write(struct kiocb *
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
ssize_t written;
+ size_t write_len;
+ pgoff_t end;
if (count != ocount)
*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
- written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
+ /*
+ * Unmap all mmappings of the file up-front.
+ *
+ * This will cause any pte dirty bits to be propagated into the
+ * pageframes for the subsequent filemap_write_and_wait().
+ */
+ write_len = iov_length(iov, *nr_segs);
+ end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
+ if (mapping_mapped(mapping))
+ unmap_mapping_range(mapping, pos, write_len, 0);
+
+ written = filemap_write_and_wait(mapping);
+ if (written)
+ goto out;
+
+ /*
+ * After a write we want buffered reads to be sure to go to disk to get
+ * the new data. We invalidate clean cached page from the region we're
+ * about to write. We do this *before* the write so that we can return
+ * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
+ */
+ if (mapping->nrpages) {
+ written = invalidate_inode_pages2_range(mapping,
+ pos >> PAGE_CACHE_SHIFT, end);
+ if (written)
+ goto out;
+ }
+
+ written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
+
+ /*
+ * Finally, try again to invalidate clean pages which might have been
+ * cached by non-direct readahead, or faulted in by get_user_pages()
+ * if the source of the write was an mmap'ed region of the file
+ * we're writing. Either one is a pretty crazy thing to do,
+ * so we don't support it 100%. If this invalidation
+ * fails, tough, the write still worked...
+ */
+ if (mapping->nrpages) {
+ invalidate_inode_pages2_range(mapping,
+ pos >> PAGE_CACHE_SHIFT, end);
+ }
+
if (written > 0) {
loff_t end = pos + written;
if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
@@ -2018,6 +2062,7 @@ generic_file_direct_write(struct kiocb *
* i_mutex is held, which protects generic_osync_inode() from
* livelocking. AIO O_DIRECT ops attempt to sync metadata here.
*/
+out:
if ((written >= 0 || written == -EIOCBQUEUED) &&
((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
@@ -2505,66 +2550,6 @@ ssize_t generic_file_aio_write(struct ki
}
EXPORT_SYMBOL(generic_file_aio_write);
-/*
- * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
- * went wrong during pagecache shootdown.
- */
-static ssize_t
-generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
- loff_t offset, unsigned long nr_segs)
-{
- struct file *file = iocb->ki_filp;
- struct address_space *mapping = file->f_mapping;
- ssize_t retval;
- size_t write_len;
- pgoff_t end = 0; /* silence gcc */
-
- /*
- * If it's a write, unmap all mmappings of the file up-front. This
- * will cause any pte dirty bits to be propagated into the pageframes
- * for the subsequent filemap_write_and_wait().
- */
- if (rw == WRITE) {
- write_len = iov_length(iov, nr_segs);
- end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
- if (mapping_mapped(mapping))
- unmap_mapping_range(mapping, offset, write_len, 0);
- }
-
- retval = filemap_write_and_wait(mapping);
- if (retval)
- goto out;
-
- /*
- * After a write we want buffered reads to be sure to go to disk to get
- * the new data. We invalidate clean cached page from the region we're
- * about to write. We do this *before* the write so that we can return
- * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
- */
- if (rw == WRITE && mapping->nrpages) {
- retval = invalidate_inode_pages2_range(mapping,
- offset >> PAGE_CACHE_SHIFT, end);
- if (retval)
- goto out;
- }
-
- retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
-
- /*
- * Finally, try again to invalidate clean pages which might have been
- * cached by non-direct readahead, or faulted in by get_user_pages()
- * if the source of the write was an mmap'ed region of the file
- * we're writing. Either one is a pretty crazy thing to do,
- * so we don't support it 100%. If this invalidation
- * fails, tough, the write still worked...
- */
- if (rw == WRITE && mapping->nrpages) {
- invalidate_inode_pages2_range(mapping, offset >> PAGE_CACHE_SHIFT, end);
- }
-out:
- return retval;
-}
-
/**
* try_to_release_page() - release old fs-specific metadata on a page
*
--
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