1 files changed, 246 insertions, 26 deletions

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index ea790623c30..f84c08029b2 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2003 Sistina Software (UK) Limited.
- * Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the GPL.
  */
@@ -15,6 +15,9 @@
 
 #define DM_MSG_PREFIX "flakey"
 
+#define all_corrupt_bio_flags_match(bio, fc)    \
+        (((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
+
 /*
  * Flakey: Used for testing only, simulates intermittent,
  * catastrophic device failure.
@@ -25,60 +28,191 @@ struct flakey_c {
         sector_t start;
         unsigned up_interval;
         unsigned down_interval;
+        unsigned long flags;
+        unsigned corrupt_bio_byte;
+        unsigned corrupt_bio_rw;
+        unsigned corrupt_bio_value;
+        unsigned corrupt_bio_flags;
+};
+
+enum feature_flag_bits {
+        DROP_WRITES
 };
 
+static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
+                          struct dm_target *ti)
+{
+        int r;
+        unsigned argc;
+        const char *arg_name;
+
+        static struct dm_arg _args[] = {
+                {0, 6, "Invalid number of feature args"},
+                {1, UINT_MAX, "Invalid corrupt bio byte"},
+                {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
+                {0, UINT_MAX, "Invalid corrupt bio flags mask"},
+        };
+
+        /* No feature arguments supplied. */
+        if (!as->argc)
+                return 0;
+
+        r = dm_read_arg_group(_args, as, &argc, &ti->error);
+        if (r)
+                return r;
+
+        while (argc) {
+                arg_name = dm_shift_arg(as);
+                argc--;
+
+                /*
+                 * drop_writes
+                 */
+                if (!strcasecmp(arg_name, "drop_writes")) {
+                        if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
+                                ti->error = "Feature drop_writes duplicated";
+                                return -EINVAL;
+                        }
+
+                        continue;
+                }
+
+                /*
+                 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
+                 */
+                if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
+                        if (!argc) {
+                                ti->error = "Feature corrupt_bio_byte requires parameters";
+                                return -EINVAL;
+                        }
+
+                        r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
+                        if (r)
+                                return r;
+                        argc--;
+
+                        /*
+                         * Direction r or w?
+                         */
+                        arg_name = dm_shift_arg(as);
+                        if (!strcasecmp(arg_name, "w"))
+                                fc->corrupt_bio_rw = WRITE;
+                        else if (!strcasecmp(arg_name, "r"))
+                                fc->corrupt_bio_rw = READ;
+                        else {
+                                ti->error = "Invalid corrupt bio direction (r or w)";
+                                return -EINVAL;
+                        }
+                        argc--;
+
+                        /*
+                         * Value of byte (0-255) to write in place of correct one.
+                         */
+                        r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
+                        if (r)
+                                return r;
+                        argc--;
+
+                        /*
+                         * Only corrupt bios with these flags set.
+                         */
+                        r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
+                        if (r)
+                                return r;
+                        argc--;
+
+                        continue;
+                }
+
+                ti->error = "Unrecognised flakey feature requested";
+                return -EINVAL;
+        }
+
+        if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
+                ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
 /*
- * Construct a flakey mapping: <dev_path> <offset> <up interval> <down interval>
+ * Construct a flakey mapping:
+ * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
+ *
+ *   Feature args:
+ *     [drop_writes]
+ *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
+ *
+ *   Nth_byte starts from 1 for the first byte.
+ *   Direction is r for READ or w for WRITE.
+ *   bio_flags is ignored if 0.
  */
 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
+        static struct dm_arg _args[] = {
+                {0, UINT_MAX, "Invalid up interval"},
+                {0, UINT_MAX, "Invalid down interval"},
+        };
+
+        int r;
         struct flakey_c *fc;
-        unsigned long long tmp;
+        unsigned long long tmpll;
+        struct dm_arg_set as;
+        const char *devname;
 
-        if (argc != 4) {
-                ti->error = "dm-flakey: Invalid argument count";
+        as.argc = argc;
+        as.argv = argv;
+
+        if (argc < 4) {
+                ti->error = "Invalid argument count";
                 return -EINVAL;
         }
 
-        fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+        fc = kzalloc(sizeof(*fc), GFP_KERNEL);
         if (!fc) {
-                ti->error = "dm-flakey: Cannot allocate linear context";
+                ti->error = "Cannot allocate linear context";
                 return -ENOMEM;
         }
         fc->start_time = jiffies;
 
-        if (sscanf(argv[1], "%llu", &tmp) != 1) {
-                ti->error = "dm-flakey: Invalid device sector";
+        devname = dm_shift_arg(&as);
+
+        if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) {
+                ti->error = "Invalid device sector";
                 goto bad;
         }
-        fc->start = tmp;
+        fc->start = tmpll;
 
-        if (sscanf(argv[2], "%u", &fc->up_interval) != 1) {
-                ti->error = "dm-flakey: Invalid up interval";
+        r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
+        if (r)
                 goto bad;
-        }
 
-        if (sscanf(argv[3], "%u", &fc->down_interval) != 1) {
-                ti->error = "dm-flakey: Invalid down interval";
+        r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
+        if (r)
                 goto bad;
-        }
 
         if (!(fc->up_interval + fc->down_interval)) {
-                ti->error = "dm-flakey: Total (up + down) interval is zero";
+                ti->error = "Total (up + down) interval is zero";
                 goto bad;
         }
 
         if (fc->up_interval + fc->down_interval < fc->up_interval) {
-                ti->error = "dm-flakey: Interval overflow";
+                ti->error = "Interval overflow";
                 goto bad;
         }
 
-        if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &fc->dev)) {
-                ti->error = "dm-flakey: Device lookup failed";
+        r = parse_features(&as, fc, ti);
+        if (r)
+                goto bad;
+
+        if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
+                ti->error = "Device lookup failed";
                 goto bad;
         }
 
         ti->num_flush_requests = 1;
+        ti->num_discard_requests = 1;
         ti->private = fc;
         return 0;
 
@@ -99,7 +233,7 @@ static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
         struct flakey_c *fc = ti->private;
 
-        return fc->start + (bi_sector - ti->begin);
+        return fc->start + dm_target_offset(ti, bi_sector);
 }
 
 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
@@ -111,6 +245,25 @@ static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
 }
 
+static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
+{
+        unsigned bio_bytes = bio_cur_bytes(bio);
+        char *data = bio_data(bio);
+
+        /*
+         * Overwrite the Nth byte of the data returned.
+         */
+        if (data && bio_bytes >= fc->corrupt_bio_byte) {
+                data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
+
+                DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
+                        "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
+                        bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
+                        (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
+                        bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
+        }
+}
+
 static int flakey_map(struct dm_target *ti, struct bio *bio,
                       union map_info *map_context)
 {
@@ -119,18 +272,71 @@ static int flakey_map(struct dm_target *ti, struct bio *bio,
 
         /* Are we alive ? */
         elapsed = (jiffies - fc->start_time) / HZ;
-        if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
+        if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
+                /*
+                 * Flag this bio as submitted while down.
+                 */
+                map_context->ll = 1;
+
+                /*
+                 * Map reads as normal.
+                 */
+                if (bio_data_dir(bio) == READ)
+                        goto map_bio;
+
+                /*
+                 * Drop writes?
+                 */
+                if (test_bit(DROP_WRITES, &fc->flags)) {
+                        bio_endio(bio, 0);
+                        return DM_MAPIO_SUBMITTED;
+                }
+
+                /*
+                 * Corrupt matching writes.
+                 */
+                if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
+                        if (all_corrupt_bio_flags_match(bio, fc))
+                                corrupt_bio_data(bio, fc);
+                        goto map_bio;
+                }
+
+                /*
+                 * By default, error all I/O.
+                 */
                 return -EIO;
+        }
 
+map_bio:
         flakey_map_bio(ti, bio);
 
         return DM_MAPIO_REMAPPED;
 }
 
+static int flakey_end_io(struct dm_target *ti, struct bio *bio,
+                         int error, union map_info *map_context)
+{
+        struct flakey_c *fc = ti->private;
+        unsigned bio_submitted_while_down = map_context->ll;
+
+        /*
+         * Corrupt successful READs while in down state.
+         * If flags were specified, only corrupt those that match.
+         */
+        if (!error && bio_submitted_while_down &&
+            (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
+            all_corrupt_bio_flags_match(bio, fc))
+                corrupt_bio_data(bio, fc);
+
+        return error;
+}
+
 static int flakey_status(struct dm_target *ti, status_type_t type,
                          char *result, unsigned int maxlen)
 {
+        unsigned sz = 0;
         struct flakey_c *fc = ti->private;
+        unsigned drop_writes;
 
         switch (type) {
         case STATUSTYPE_INFO:
@@ -138,9 +344,22 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
                 break;
 
         case STATUSTYPE_TABLE:
-                snprintf(result, maxlen, "%s %llu %u %u", fc->dev->name,
-                         (unsigned long long)fc->start, fc->up_interval,
-                         fc->down_interval);
+                DMEMIT("%s %llu %u %u ", fc->dev->name,
+                       (unsigned long long)fc->start, fc->up_interval,
+                       fc->down_interval);
+
+                drop_writes = test_bit(DROP_WRITES, &fc->flags);
+                DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
+
+                if (drop_writes)
+                        DMEMIT("drop_writes ");
+
+                if (fc->corrupt_bio_byte)
+                        DMEMIT("corrupt_bio_byte %u %c %u %u ",
+                               fc->corrupt_bio_byte,
+                               (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
+                               fc->corrupt_bio_value, fc->corrupt_bio_flags);
+
                 break;
         }
         return 0;
@@ -177,11 +396,12 @@ static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_
 
 static struct target_type flakey_target = {
         .name   = "flakey",
-        .version = {1, 1, 0},
+        .version = {1, 2, 0},
         .module = THIS_MODULE,
         .ctr    = flakey_ctr,
         .dtr    = flakey_dtr,
         .map    = flakey_map,
+        .end_io = flakey_end_io,
         .status = flakey_status,
         .ioctl  = flakey_ioctl,
         .merge  = flakey_merge,