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9p: saner ->write_end() on failing copy into non-uptodate page 

If we had a short copy into an uptodate page, there's no reason
whatsoever to zero anything; OTOH, if that page had _not_ been
uptodate, we must have been trying to overwrite it completely
and got a short copy.  In that case, overwriting the end with
zeroes, marking uptodate and sending to server is just plain
wrong.  Just unlock, keep it non-uptodate and return 0.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-08-29 20:56:35 -04:00
parent 43388b21e7
commit 77469c3f57
1 changed files with 4 additions and 11 deletions
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15
fs/9p/vfs_addr.c
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@ -309,18 +309,10 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
if (unlikely(copied < len)) {
/*
* zero out the rest of the area
*/
unsigned from = pos & (PAGE_SIZE - 1);
zero_user(page, from + copied, len - copied);
flush_dcache_page(page);
if (unlikely(copied < len && !PageUptodate(page))) {
copied = 0;
goto out;
}
if (!PageUptodate(page))
SetPageUptodate(page);
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold the i_mutex.
@ -330,6 +322,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
i_size_write(inode, last_pos);
}
set_page_dirty(page);
out:
unlock_page(page);
put_page(page);