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SubjectRe: [PATCH] VFS mmap wrong behavior when I/O failure occurs
fs <fs@ercist.iscas.ac.cn> wrote:
>
> --- linux-2.6.11.8-orig/fs/buffer.c 2005-05-11 14:41:03.000000000
> -0400

Your email client wordwrapped the patch. Please fix it.

> +++ linux-2.6.11.8/fs/buffer.c 2005-05-11 14:38:55.000000000 -0400
> @@ -2105,7 +2105,6 @@ int block_read_full_page(struct page *pa
> memset(kaddr + i * blocksize, 0,
> blocksize);
> flush_dcache_page(page);
> kunmap_atomic(kaddr, KM_USER0);
> - set_buffer_uptodate(bh);
> continue;
> }
> /*

This patch will break the kernel's regular handling of file holes -
!buffer_mapped() means that there was no disk mapping for this buffer: it
sits over a hole in the file. Zeroing out the buffer and marking it
uptodate is correct behaviour.

You probably want something like this:

--- 25/fs/buffer.c~a 2005-05-11 01:15:13.000000000 -0700
+++ 25-akpm/fs/buffer.c 2005-05-11 01:16:39.000000000 -0700
@@ -2094,9 +2094,12 @@ int block_read_full_page(struct page *pa
continue;

if (!buffer_mapped(bh)) {
+ int err = 0;
+
fully_mapped = 0;
if (iblock < lblock) {
- if (get_block(inode, iblock, bh, 0))
+ err = get_block(inode, iblock, bh, 0);
+ if (err)
SetPageError(page);
}
if (!buffer_mapped(bh)) {
@@ -2104,7 +2107,8 @@ int block_read_full_page(struct page *pa
memset(kaddr + i * blocksize, 0, blocksize);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
- set_buffer_uptodate(bh);
+ if (!err)
+ set_buffer_uptodate(bh);
continue;
}
/*
_

-
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