linux-kernel - [PATCH] Staging: zram: initialize device on first read

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Message-ID: <4D5D48C5.3090906@redhat.com>
Date:	Thu, 17 Feb 2011 17:11:49 +0100
From:	Jerome Marchand <jmarchan@...hat.com>
To:	Nitin Gupta <ngupta@...are.org>
CC:	Greg Kroah-Hartman <gregkh@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] Staging: zram: initialize device on first read


Currently the device is initialized when first write is done to the
device. Any read attempt before the first write would fail, including
"hidden" read the user may not know about (as for example if he tries
to write a partial block).

This patch initializes the device on first request, whether read or
write.

Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
---
 zram_drv.c |   19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 5fdf9d2..aab4ec4 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -211,11 +211,6 @@ static void zram_read(struct zram *zram, struct bio *bio)
 	u32 index;
 	struct bio_vec *bvec;
 
-	if (unlikely(!zram->init_done)) {
-		bio_endio(bio, -ENXIO);
-		return;
-	}
-
 	zram_stat64_inc(zram, &zram->stats.num_reads);
 	index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 
@@ -286,20 +281,15 @@ out:
 
 static void zram_write(struct zram *zram, struct bio *bio)
 {
-	int i, ret;
+	int i;
 	u32 index;
 	struct bio_vec *bvec;
 
-	if (unlikely(!zram->init_done)) {
-		ret = zram_init_device(zram);
-		if (ret)
-			goto out;
-	}
-
 	zram_stat64_inc(zram, &zram->stats.num_writes);
 	index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 
 	bio_for_each_segment(bvec, bio, i) {
+		int ret;
 		u32 offset;
 		size_t clen;
 		struct zobj_header *zheader;
@@ -445,6 +435,11 @@ static int zram_make_request(struct request_queue *queue, struct bio *bio)
 		return 0;
 	}
 
+	if (unlikely(!zram->init_done) && zram_init_device(zram)) {
+		bio_io_error(bio);
+		return 0;
+	}
+
 	switch (bio_data_dir(bio)) {
 	case READ:
 		zram_read(zram, bio);
--
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