[PATCH 1/3] vfs: Unmap underlying metadata of new data buffers only when buffer is mapped

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



When we do delayed allocation of some buffer, we want to signal to VFS that
the buffer is new (set buffer_new) so that it properly zeros out everything.
But we don't have the buffer mapped yet so we cannot really unmap underlying
metadata in this state. Make VFS avoid doing unmapping of metadata when the
buffer is not yet mapped.

Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/buffer.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 3e7dca2..0f2ba29 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1688,8 +1688,9 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
 			if (buffer_new(bh)) {
 				/* blockdev mappings never come here */
 				clear_buffer_new(bh);
-				unmap_underlying_metadata(bh->b_bdev,
-							bh->b_blocknr);
+				if (buffer_mapped(bh))
+					unmap_underlying_metadata(bh->b_bdev,
+						bh->b_blocknr);
 			}
 		}
 		bh = bh->b_this_page;
@@ -1875,8 +1876,9 @@ int block_prepare_write(struct page *page, unsigned from, unsigned to,
 			if (err)
 				break;
 			if (buffer_new(bh)) {
-				unmap_underlying_metadata(bh->b_bdev,
-							bh->b_blocknr);
+				if (buffer_mapped(bh))
+					unmap_underlying_metadata(bh->b_bdev,
+						bh->b_blocknr);
 				if (PageUptodate(page)) {
 					clear_buffer_new(bh);
 					set_buffer_uptodate(bh);
@@ -2514,7 +2516,7 @@ int nobh_write_begin(struct address_space *mapping,
 			goto failed;
 		if (!buffer_mapped(bh))
 			is_mapped_to_disk = 0;
-		if (buffer_new(bh))
+		if (buffer_new(bh) && buffer_mapped(bh))
 			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 		if (PageUptodate(page)) {
 			set_buffer_uptodate(bh);
-- 
1.6.4.2

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Reiser Filesystem Development]     [Ceph FS]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Yosemite National Park]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Device Mapper]     [Linux Media]

  Powered by Linux