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[GFS2] Patch to fix mmap of stuffed files 

If a stuffed file is mmaped and a page fault is generated at some offset
above the initial page, we need to create a zero page to hang the buffer
heads off before we can unstuff the file. This is a fix for bz #236087

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2007-04-20 09:18:30 +01:00
parent 476c006be0
commit bf126aee6d
1 changed files with 14 additions and 3 deletions
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17
fs/gfs2/ops_address.c
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@ -197,7 +197,19 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
void *kaddr;
int error;
BUG_ON(page->index);
/*
* Due to the order of unstuffing files and ->nopage(), we can be
* asked for a zero page in the case of a stuffed file being extended,
* so we need to supply one here. It doesn't happen often.
*/
if (unlikely(page->index)) {
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, PAGE_CACHE_SIZE);
kunmap_atomic(kaddr, KM_USER0);
flush_dcache_page(page);
SetPageUptodate(page);
return 0;
}
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
@ -208,9 +220,8 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
ip->i_di.di_size);
memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
kunmap_atomic(kaddr, KM_USER0);
flush_dcache_page(page);
brelse(dibh);
SetPageUptodate(page);
return 0;