Commit 769989a4 authored Dec 02, 2013 by Bodo Stroesser Committed by James Bottomley Dec 19, 2013

[SCSI] st: fix enlarge_buffer



This patch removes a bug in enlarge_buffer() that can make a
read or write fail under special conditions.

After changing TRY_DIRECT_IO to 0 and ST_MAX_SG to 32 in
st_options.h, a program that writes a first block of 128k and
than a second bigger block (e.g. 256k) fails. The second write
returns errno EOVERFLOW, as enlarge_buffer() checks the sg list
and detects that it already is full.
As enlarge_buffer uses different page allocation orders
depending on the size of the buffer needed, the check does not
make sense.

Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

parent 762a86a9

drivers/scsi/st.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -3719,7 +3719,7 @@ static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)

		static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
		{
		int segs, nbr, max_segs, b_size, order, got;
		int segs, max_segs, b_size, order, got;
		gfp_t priority;

		if (new_size <= STbuffer->buffer_size)
		@@ -3729,9 +3729,6 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
		normalize_buffer(STbuffer); /* Avoid extra segment */

		max_segs = STbuffer->use_sg;
		nbr = max_segs - STbuffer->frp_segs;
		if (nbr <= 0)
		return 0;

		priority = GFP_KERNEL \| __GFP_NOWARN;
		if (need_dma)

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