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vfs: clear to the end of the buffer on reads

PATCH Superseded Dan Carpenter 2 participants 4 messages Dec 5, 2012

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Dan Carpenter

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#0 lore raw

PATCH 1/1 vfs: clear to the end of the buffer on reads

READ is zero so this test is always false. (rw = READ) was intended.

Signed-off-by Dan Carpenter <[email protected]>
fs/buffer.c +1 -1
index 70ed4d8..e0a59c6 100644
@@ -2931,7 +2931,7 @@ static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh)
 	bio->bi_io_vec[0].bv_len = bytes;
 
 	/* ..and clear the end of the buffer for reads */
-	if (rw & READ) {
+	if (rw = READ) {
 		void *kaddr = kmap_atomic(bh->b_page);
 		memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes);
 		kunmap_atomic(kaddr);
#1 lore raw
Quoted 1 line · Dan Carpenter

READ is zero so this test is always false. (rw = READ) was intended.

Actually, that really *is* a bitmask, but yeah, the test is wrong.

The correct test is

((rw & RW_MASK) = READ)

because the field can have other bits set too (REQ_SYNC or REQ_META or whatever - read-ahead, other bits)

Alternatively, just "!(rw & WRITE)" I guess.

But thanks for noticing.

Linus

author
#2 lore raw
Quoted 9 lines · Linus Torvalds
Quoted 1 line · Dan Carpenter

READ is zero so this test is always false. (rw = READ) was intended.

Actually, that really *is* a bitmask, but yeah, the test is wrong.

The correct test is

((rw & RW_MASK) = READ)

Ah. Of course. I'll send a v2.

regards,
dan carpenter

author
#3 lore raw

PATCH v2 1/1 vfs: clear to the end of the buffer on reads

In reply to Linus Torvalds

READ is zero so this test is always false. If ((rw & RW_MASK) = READ) was intended.

Signed-off-by Dan Carpenter <[email protected]>

---
v2: I didn't mask out the other flags in the first version

fs/buffer.c +1 -1
index 70ed4d8..e0a59c6 100644
@@ -2931,7 +2931,7 @@ static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh)
 	bio->bi_io_vec[0].bv_len = bytes;
 
 	/* ..and clear the end of the buffer for reads */
-	if (rw & READ) {
+	if ((rw & RW_MASK) = READ) {
 		void *kaddr = kmap_atomic(bh->b_page);
 		memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes);
 		kunmap_atomic(kaddr);