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NFS: Optimise append writes with holes

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If a file is being extended, and we're creating a hole, we might as well
declare the entire page to be up to date.

This patch significantly improves the write performance for sparse files
in the case where lseek(SEEK_END) is used to append several non-contiguous
writes at intervals of < PAGE_SIZE.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2008-06-10 18:31:00 -04:00
parent b390c2b55c
commit efc91ed019
2 changed files with 23 additions and 9 deletions
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20
fs/nfs/file.c
View file

@ -344,6 +344,26 @@ static int nfs_write_end(struct file *file, struct address_space *mapping,
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
int status;
/*
* Zero any uninitialised parts of the page, and then mark the page
* as up to date if it turns out that we're extending the file.
*/
if (!PageUptodate(page)) {
unsigned pglen = nfs_page_length(page);
unsigned end = offset + len;
if (pglen == 0) {
zero_user_segments(page, 0, offset,
end, PAGE_CACHE_SIZE);
SetPageUptodate(page);
} else if (end >= pglen) {
zero_user_segment(page, end, PAGE_CACHE_SIZE);
if (offset == 0)
SetPageUptodate(page);
} else
zero_user_segment(page, pglen, PAGE_CACHE_SIZE);
}
lock_kernel();
status = nfs_updatepage(file, page, offset, copied);
unlock_kernel();

12
fs/nfs/write.c
View file

@ -616,7 +616,7 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
spin_unlock(&inode->i_lock);
radix_tree_preload_end();
req = new;
goto zero_page;
goto out;
}
spin_unlock(&inode->i_lock);
@ -649,19 +649,13 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
req->wb_offset = offset;
req->wb_pgbase = offset;
req->wb_bytes = max(end, rqend) - req->wb_offset;
goto zero_page;
goto out;
}
if (end > rqend)
req->wb_bytes = end - req->wb_offset;
return req;
zero_page:
/* If this page might potentially be marked as up to date,
* then we need to zero any uninitalised data. */
if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
&& !PageUptodate(req->wb_page))
zero_user_segment(req->wb_page, req->wb_bytes, PAGE_CACHE_SIZE);
out:
return req;
}