exofs: Recover in the case of read-passed-end-of-file

In check_io, implement the case of reading passed end of
file, by clearing the pages and recover with no error. In
a raid arrangement this can become a legitimate situation
in case of holes in the file.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

diff --git a/fs/exofs/ios.c b/fs/exofs/ios.c
index 3cc0dd3..439c5d0 100644 (file)
--- a/fs/exofs/ios.c
+++ b/fs/exofs/ios.c
@@ -173,6 +173,21 @@ static int exofs_io_execute(struct exofs_io_state *ios)
        return ret;
 }
 
+static void _clear_bio(struct bio *bio)
+{
+       struct bio_vec *bv;
+       unsigned i;
+
+       __bio_for_each_segment(bv, bio, i, 0) {
+               unsigned this_count = bv->bv_len;
+
+               if (likely(PAGE_SIZE == this_count))
+                       clear_highpage(bv->bv_page);
+               else
+                       zero_user(bv->bv_page, bv->bv_offset, this_count);
+       }
+}
+
 int exofs_check_io(struct exofs_io_state *ios, u64 *resid)
 {
        enum osd_err_priority acumulated_osd_err = 0;
@@ -181,16 +196,25 @@ int exofs_check_io(struct exofs_io_state *ios, u64 *resid)
 
        for (i = 0; i < ios->numdevs; i++) {
                struct osd_sense_info osi;
-               int ret = osd_req_decode_sense(ios->per_dev[i].or, &osi);
+               struct osd_request *or = ios->per_dev[i].or;
+               int ret;
+
+               if (unlikely(!or))
+                       continue;
 
+               ret = osd_req_decode_sense(or, &osi);
                if (likely(!ret))
                        continue;
 
-               if (unlikely(ret == -EFAULT)) {
-                       EXOFS_DBGMSG("%s: EFAULT Need page clear\n", __func__);
-                       /*FIXME: All the pages in this device range should:
-                        *      clear_highpage(page);
-                        */
+               if (OSD_ERR_PRI_CLEAR_PAGES == osi.osd_err_pri) {
+                       /* start read offset passed endof file */
+                       _clear_bio(ios->per_dev[i].bio);
+                       EXOFS_DBGMSG("start read offset passed end of file "
+                               "offset=0x%llx, length=0x%llx\n",
+                               _LLU(ios->offset),
+                               _LLU(ios->length));
+
+                       continue; /* we recovered */
                }
 
                if (osi.osd_err_pri >= acumulated_osd_err) {