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>

1 files changed, 30 insertions, 6 deletions

diff --git a/fs/exofs/ios.c b/fs/exofs/ios.c
index 3cc0dd3f0eb2..439c5d097b27 100644
--- 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) {