From: Jingbo Xu jefflexu@linux.alibaba.com
[ Upstream commit e6d9f9ba111b56154f1b1120252aff269cebd49c ]
For unmapped range, the returned map.m_llen is zero, and thus the calculated count is unexpected zero.
Prior to the refactoring introduced by commit 1ae9470c3e14 ("erofs: clean up .read_folio() and .readahead() in fscache mode"), only the readahead routine suffers from this. With the refactoring of making .read_folio() and .readahead() calling one common routine, both read_folio and readahead have this issue now.
Fix this by calculating count separately in unmapped condition.
Fixes: c665b394b9e8 ("erofs: implement fscache-based data readahead") Fixes: 1ae9470c3e14 ("erofs: clean up .read_folio() and .readahead() in fscache mode") Signed-off-by: Jingbo Xu jefflexu@linux.alibaba.com Reviewed-by: Gao Xiang hsiangkao@linux.alibaba.com Reviewed-by: Chao Yu chao@kernel.org Link: https://lore.kernel.org/r/20221104054028.52208-3-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/erofs/fscache.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index 508b1a4df15e..8585e324298c 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -288,15 +288,16 @@ static int erofs_fscache_data_read(struct address_space *mapping, return PAGE_SIZE; }
- count = min_t(size_t, map.m_llen - (pos - map.m_la), len); - DBG_BUGON(!count || count % PAGE_SIZE); - if (!(map.m_flags & EROFS_MAP_MAPPED)) { + count = len; iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, count); iov_iter_zero(count, &iter); return count; }
+ count = min_t(size_t, map.m_llen - (pos - map.m_la), len); + DBG_BUGON(!count || count % PAGE_SIZE); + mdev = (struct erofs_map_dev) { .m_deviceid = map.m_deviceid, .m_pa = map.m_pa,