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Subject[PATCH 1/2] erofs: pass accurate blob size to prepare_ondemand_read()
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To make fscache mode support PAGE_SIZE larger than 4KB, the blob image
size may be small than the multiples of PAGE_SIZE (as erofs block size
is no larger than 4KB), while the file range of the blob requested to
read is multiples of PAGE_SIZE and may be larger than the blob image
size.

Therefore we need the accurate blob size, so that the EOF part could be
distinguished and zero-filled then.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
fs/erofs/fscache.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 87ff35bff8d5..f7a1e147d0f4 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -125,7 +125,7 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,

DBG_BUGON(len > req->len - req->submitted);

- ret = fscache_begin_read_operation(cres, cookie);
+ ret = fscache_begin_wait_operation(cres, cookie, FSCACHE_WANT_READ);
if (ret)
return ret;

@@ -134,8 +134,17 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
size_t slen = len - done;
unsigned long flags = 1 << NETFS_SREQ_ONDEMAND;

+ if (sstart >= cookie->object_size) {
+ iov_iter_xarray(&iter, ITER_DEST, &req->mapping->i_pages,
+ lstart + done, slen);
+ iov_iter_zero(slen, &iter);
+ done += slen;
+ continue;
+ }
+
+ slen = min_t(size_t, slen, cookie->object_size - sstart);
source = cres->ops->prepare_ondemand_read(cres,
- sstart, &slen, LLONG_MAX, &flags, 0);
+ sstart, &slen, cookie->object_size, &flags, 0);
if (WARN_ON(slen == 0))
source = NETFS_INVALID_READ;
if (source != NETFS_READ_FROM_CACHE) {
--
2.19.1.6.gb485710b
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