diff options
author | Gao Xiang <hsiangkao@redhat.com> | 2021-02-09 21:06:18 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-04 11:38:28 +0100 |
commit | 03c9bf033c7b53581a38513fac46e7d5959a0a86 (patch) | |
tree | b9aef18f1fdf9ed735d3b2fdd2533771713f7fde /fs/erofs/zmap.c | |
parent | 2fe92153013c490f739e6862c08848126501f172 (diff) |
erofs: initialized fields can only be observed after bit is set
commit ce063129181312f8781a047a50be439c5859747b upstream.
Currently, although set_bit() & test_bit() pairs are used as a fast-
path for initialized configurations. However, these atomic ops are
actually relaxed forms. Instead, load-acquire & store-release form is
needed to make sure uninitialized fields won't be observed in advance
here (yet no such corresponding bitops so use full barriers instead.)
Link: https://lore.kernel.org/r/20210209130618.15838-1-hsiangkao@aol.com
Fixes: 62dc45979f3f ("staging: erofs: fix race of initializing xattrs of a inode at the same time")
Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support")
Cc: <stable@vger.kernel.org> # 5.3+
Reported-by: Huang Jianan <huangjianan@oppo.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/erofs/zmap.c')
-rw-r--r-- | fs/erofs/zmap.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index ae325541884e..14d2de35110c 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -36,8 +36,14 @@ static int z_erofs_fill_inode_lazy(struct inode *inode) void *kaddr; struct z_erofs_map_header *h; - if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) + if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) { + /* + * paired with smp_mb() at the end of the function to ensure + * fields will only be observed after the bit is set. + */ + smp_mb(); return 0; + } if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_Z_BIT, TASK_KILLABLE)) return -ERESTARTSYS; @@ -83,6 +89,8 @@ static int z_erofs_fill_inode_lazy(struct inode *inode) vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits + ((h->h_clusterbits >> 5) & 7); + /* paired with smp_mb() at the beginning of the function */ + smp_mb(); set_bit(EROFS_I_Z_INITED_BIT, &vi->flags); unmap_done: kunmap_atomic(kaddr); |