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nfs: add memory barriers around NFS_INO_INVALID_DATA and NFS_INO_INVALIDATING 

If the setting of NFS_INO_INVALIDATING gets reordered to before the
clearing of NFS_INO_INVALID_DATA, then another task may hit a race
window where both appear to be clear, even though the inode's pages are
still in need of invalidation. Fix this by adding the appropriate memory
barriers.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Jeff Layton 2014-01-28 13:47:46 -05:00 committed by Trond Myklebust
parent 17dfeb9113
commit 4db72b40fd
3 changed files with 13 additions and 3 deletions
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14
fs/nfs/dir.c
View File

@ -274,6 +274,15 @@ out_eof:
return -EBADCOOKIE;
}
static bool
nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
{
if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
return false;
smp_rmb();
return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
}
static
int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
{
@ -287,9 +296,8 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
struct nfs_open_dir_context *ctx = desc->file->private_data;
new_pos = desc->current_index + i;
if (ctx->attr_gencount != nfsi->attr_gencount
|| (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
|| test_bit(NFS_INO_INVALIDATING, &nfsi->flags)) {
if (ctx->attr_gencount != nfsi->attr_gencount ||
!nfs_readdir_inode_mapping_valid(nfsi)) {
ctx->duped = 0;
ctx->attr_gencount = nfsi->attr_gencount;
} else if (new_pos < desc->ctx->pos) {

1
fs/nfs/inode.c
View File

@ -1050,6 +1050,7 @@ int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
}
set_bit(NFS_INO_INVALIDATING, bitlock);
smp_wmb();
nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
spin_unlock(&inode->i_lock);
trace_nfs_invalidate_mapping_enter(inode);

1
fs/nfs/write.c
View File

@ -915,6 +915,7 @@ static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
goto out;
if (nfsi->cache_validity & (NFS_INO_INVALID_DATA|NFS_INO_REVAL_PAGECACHE))
return false;
smp_rmb();
if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
return false;
out: