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Date: Tue, 25 May 2021 15:50:50 +0200 From: Jan Kara <jack@...e.cz> To: <linux-fsdevel@...r.kernel.org> Cc: Christoph Hellwig <hch@...radead.org>, Dave Chinner <david@...morbit.com>, ceph-devel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>, Damien Le Moal <damien.lemoal@....com>, "Darrick J. Wong" <darrick.wong@...cle.com>, Jaegeuk Kim <jaegeuk@...nel.org>, Jeff Layton <jlayton@...nel.org>, Johannes Thumshirn <jth@...nel.org>, linux-cifs@...r.kernel.org, <linux-ext4@...r.kernel.org>, linux-f2fs-devel@...ts.sourceforge.net, <linux-mm@...ck.org>, <linux-xfs@...r.kernel.org>, Miklos Szeredi <miklos@...redi.hu>, Steve French <sfrench@...ba.org>, Ted Tso <tytso@....edu>, Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz> Subject: [PATCH 13/13] cifs: Fix race between hole punch and page fault Cifs has a following race between hole punching and page fault: CPU1 CPU2 smb3_fallocate() smb3_punch_hole() truncate_pagecache_range() filemap_fault() - loads old data into the page cache SMB2_ioctl(..., FSCTL_SET_ZERO_DATA, ...) And now we have stale data in the page cache. Fix the problem by locking out faults (as well as reads) using mapping->invalidate_lock while hole punch is running. CC: Steve French <sfrench@...ba.org> CC: linux-cifs@...r.kernel.org Signed-off-by: Jan Kara <jack@...e.cz> --- fs/cifs/smb2ops.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index dd0eb665b680..b0a0f8b34add 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -3579,6 +3579,7 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon, return rc; } + down_write(&inode->i_mapping->invalidate_lock); /* * We implement the punch hole through ioctl, so we need remove the page * caches first, otherwise the data may be inconsistent with the server. @@ -3596,6 +3597,7 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon, sizeof(struct file_zero_data_information), CIFSMaxBufSize, NULL, NULL); free_xid(xid); + up_write(&inode->i_mapping->invalidate_lock); return rc; } -- 2.26.2
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