zram: fix incorrect stat with failed_reads

Since we allocate a temporary buffer in zram_bvec_read to handle partial
page operations in commit 924bd88d703e ("Staging: zram: allow partial
page operations"), our ->failed_reads value may be incorrect as we do
not increase its value when failing to allocate the temporary buffer.

Let's fix this issue and correct the annotation of failed_reads.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 0cf1e9d6c34d4c82ac3af8015594849814843d36)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index a21f466c4e1563ce61a479c4a9c3a54545ae85e2..600aeab83d2a7c9cd054bf6ec696e62714deae76 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -377,7 +377,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
        /* Should NEVER happen. Return bio error if it does. */
        if (unlikely(ret)) {
                pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
-               atomic64_inc(&zram->stats.failed_reads);
                return ret;
        }
 
@@ -546,8 +545,6 @@ out:
                zcomp_strm_release(zram->comp, zstrm);
        if (is_partial_io(bvec))
                kfree(uncmem);
-       if (ret)
-               atomic64_inc(&zram->stats.failed_writes);
        return ret;
 }
 
@@ -565,6 +562,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
                ret = zram_bvec_write(zram, bvec, index, offset);
        }
 
+       if (unlikely(ret)) {
+               if (rw == READ)
+                       atomic64_inc(&zram->stats.failed_reads);
+               else
+                       atomic64_inc(&zram->stats.failed_writes);
+       }
+
        return ret;
 }
 

diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 5b0afde729cd885286f48d31991f7bc98f44328b..e0f725c87cc617b4ade4c7574c18fa6ce15ca828 100644 (file)
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -84,7 +84,7 @@ struct zram_stats {
        atomic64_t compr_data_size;     /* compressed size of pages stored */
        atomic64_t num_reads;   /* failed + successful */
        atomic64_t num_writes;  /* --do-- */
-       atomic64_t failed_reads;        /* should NEVER! happen */
+       atomic64_t failed_reads;        /* can happen when memory is too low */
        atomic64_t failed_writes;       /* can happen when memory is too low */
        atomic64_t invalid_io;  /* non-page-aligned I/O requests */
        atomic64_t notify_free; /* no. of swap slot free notifications */