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From: Nick Piggin <npiggin@suse.de>
To: Linux Memory Management <linux-mm@kvack.org>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux Filesystems <linux-fsdevel@vger.kernel.org>,
	Nick Piggin <npiggin@suse.de>, Andrew Morton <akpm@osdl.org>
Subject: [patch 4/10] mm: generic_file_buffered_write cleanup
Date: Sat, 13 Jan 2007 04:24:52 +0100 (CET)	[thread overview]
Message-ID: <20070113011236.9449.34557.sendpatchset@linux.site> (raw)
In-Reply-To: <20070113011159.9449.4327.sendpatchset@linux.site>

From: Andrew Morton <akpm@osdl.org>

Clean up buffered write code. Rename some variables and fix some types.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Nick Piggin <npiggin@suse.de>

Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -1854,16 +1854,15 @@ generic_file_buffered_write(struct kiocb
 		size_t count, ssize_t written)
 {
 	struct file *file = iocb->ki_filp;
-	struct address_space * mapping = file->f_mapping;
+	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;
 	struct page	*page;
 	struct page	*cached_page = NULL;
-	size_t		bytes;
 	struct pagevec	lru_pvec;
 	const struct iovec *cur_iov = iov; /* current iovec */
-	size_t		iov_base = 0;	   /* offset in the current iovec */
+	size_t		iov_offset = 0;	   /* offset in the current iovec */
 	char __user	*buf;
 
 	pagevec_init(&lru_pvec, 0);
@@ -1874,31 +1873,33 @@ generic_file_buffered_write(struct kiocb
 	if (likely(nr_segs == 1))
 		buf = iov->iov_base + written;
 	else {
-		filemap_set_next_iovec(&cur_iov, &iov_base, written);
-		buf = cur_iov->iov_base + iov_base;
+		filemap_set_next_iovec(&cur_iov, &iov_offset, written);
+		buf = cur_iov->iov_base + iov_offset;
 	}
 
 	do {
-		unsigned long index;
-		unsigned long offset;
-		unsigned long maxlen;
-		size_t copied;
+		pgoff_t index;		/* Pagecache index for current page */
+		unsigned long offset;	/* Offset into pagecache page */
+		unsigned long maxlen;	/* Bytes remaining in current iovec */
+		size_t bytes;		/* Bytes to write to page */
+		size_t copied;		/* Bytes copied from user */
 
-		offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
+		offset = (pos & (PAGE_CACHE_SIZE - 1));
 		index = pos >> PAGE_CACHE_SHIFT;
 		bytes = PAGE_CACHE_SIZE - offset;
 		if (bytes > count)
 			bytes = count;
 
+		maxlen = cur_iov->iov_len - iov_offset;
+		if (maxlen > bytes)
+			maxlen = bytes;
+
 		/*
 		 * 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.
 		 */
-		maxlen = cur_iov->iov_len - iov_base;
-		if (maxlen > bytes)
-			maxlen = bytes;
 		fault_in_pages_readable(buf, maxlen);
 
 		page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
@@ -1929,7 +1930,7 @@ generic_file_buffered_write(struct kiocb
 							buf, bytes);
 		else
 			copied = filemap_copy_from_user_iovec(page, offset,
-						cur_iov, iov_base, bytes);
+						cur_iov, iov_offset, bytes);
 		flush_dcache_page(page);
 		status = a_ops->commit_write(file, page, offset, offset+bytes);
 		if (status == AOP_TRUNCATED_PAGE) {
@@ -1947,12 +1948,12 @@ generic_file_buffered_write(struct kiocb
 				buf += status;
 				if (unlikely(nr_segs > 1)) {
 					filemap_set_next_iovec(&cur_iov,
-							&iov_base, status);
+							&iov_offset, status);
 					if (count)
 						buf = cur_iov->iov_base +
-							iov_base;
+							iov_offset;
 				} else {
-					iov_base += status;
+					iov_offset += status;
 				}
 			}
 		}

  parent reply	other threads:[~2007-01-13  3:27 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-13  3:24 [patch 0/10] buffered write deadlock fix Nick Piggin
2007-01-13  3:24 ` [patch 1/10] fs: libfs buffered write leak fix Nick Piggin
2007-01-13  3:24 ` [patch 2/10] mm: revert "generic_file_buffered_write(): handle zero length iovec segments" Nick Piggin
2007-01-13  3:24 ` [patch 3/10] mm: revert "generic_file_buffered_write(): deadlock on vectored write" Nick Piggin
2007-01-13  3:24 ` Nick Piggin [this message]
2007-01-13  3:25 ` [patch 5/10] mm: debug write deadlocks Nick Piggin
2007-01-13  3:25 ` [patch 6/10] mm: be sure to trim blocks Nick Piggin
2007-01-14 14:25   ` Dmitriy Monakhov
2007-01-20  3:50     ` Nick Piggin
2007-01-16 17:36   ` Peter Zijlstra
2007-01-16 19:14     ` Peter Zijlstra
2007-01-20  3:52       ` Nick Piggin
2007-01-13  3:25 ` [patch 7/10] mm: cleanup pagecache insertion operations Nick Piggin
2007-01-13  3:25 ` [patch 8/10] mm: generic_file_buffered_write cleanup more Nick Piggin
2007-01-13  3:25 ` [patch 9/10] mm: generic_file_buffered_write iovec cleanup Nick Piggin
2007-01-13  3:25 ` [patch 10/10] mm: fix pagecache write deadlocks Nick Piggin
2007-01-14  3:59   ` Nick Piggin

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