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NFS: Deal correctly with attribute generation counter overflow

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[ Upstream commit 9fdbfad1777cb4638f489eeb62d85432010c0031 ]

We need to use unsigned long subtraction and then convert to signed in
order to deal correcly with C overflow rules.

Fixes: f5062003465c ("NFS: Set an attribute barrier on all updates")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Trond Myklebust 2021-03-29 16:46:05 -04:00 committed by Greg Kroah-Hartman
parent cbc868ea28
commit d21a5950cc
1 changed files with 4 additions and 4 deletions
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8
fs/nfs/inode.c
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@ -1642,10 +1642,10 @@ EXPORT_SYMBOL_GPL(_nfs_display_fhandle);
*/
static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
{
const struct nfs_inode *nfsi = NFS_I(inode);
unsigned long attr_gencount = NFS_I(inode)->attr_gencount;
return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||
((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);
return (long)(fattr->gencount - attr_gencount) > 0 ||
(long)(attr_gencount - nfs_read_attr_generation_counter()) > 0;
}
static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
@ -2074,7 +2074,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
nfsi->attrtimeo_timestamp = now;
}
/* Set the barrier to be more recent than this fattr */
if ((long)fattr->gencount - (long)nfsi->attr_gencount > 0)
if ((long)(fattr->gencount - nfsi->attr_gencount) > 0)
nfsi->attr_gencount = fattr->gencount;
}