From cd8bfa9c8a13cf3facc5731da17e10188b3795d1 Mon Sep 17 00:00:00 2001
From: Prasad Joshi <prasadjoshi.linux@gmail.com>
Date: Mon, 2 Apr 2012 09:23:04 +0530
Subject: logfs: initialize the number of iovecs in bio
This fixes the following crash when a LogFS file system, created on a
encrypted LVM volume, was mounted
[ 526.548034] BUG: unable to handle kernel NULL pointer dereference at
[ 526.550106] IP: [<ffffffff8131ecab>] memcpy+0xb/0x120
[ 526.551008] PGD bd60067 PUD 1778d067 PMD 0
[ 526.551783] Oops: 0000 [#1] SMP
<d>Pid: 2043, comm: mount
<d>RIP: 0010:[<ffffffff8131ecab>] [<ffffffff8131ecab>] memcpy+0xb/0x120
Call Trace:
kcryptd_io_read+0xdb/0x100
crypt_map+0xfd/0x190
__map_bio+0x48/0x150
__split_and_process_bio+0x51b/0x630
dm_request+0x138/0x230
generic_make_request+0xca/0x100
submit_bio+0x87/0x110
sync_request+0xdd/0x120 [logfs]
bdev_readpage+0x2e/0x70 [logfs]
do_read_cache_page+0x82/0x180
logfs_mount+0x2ad/0x770 [logfs]
mount_fs+0x47/0x1c0
vfs_kern_mount+0x72/0x110
do_kern_mount+0x54/0x110
do_mount+0x520/0x7f0
sys_mount+0x90/0xe0
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=42292
Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
---
fs/logfs/dev_bdev.c | 1 +
1 file changed, 1 insertion(+)
(limited to 'fs/logfs/dev_bdev.c')
diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
index df0de27c273..ea29df36893 100644
--- a/fs/logfs/dev_bdev.c
+++ b/fs/logfs/dev_bdev.c
@@ -26,6 +26,7 @@ static int sync_request(struct page *page, struct block_device *bdev, int rw)
struct completion complete;
bio_init(&bio);
+ bio.bi_max_vecs = 1;
bio.bi_io_vec = &bio_vec;
bio_vec.bv_page = page;
bio_vec.bv_len = PAGE_SIZE;
--
cgit v1.2.3-70-g09d2
From 9f0bbd8ca7905fcc0602c038013b095322fec939 Mon Sep 17 00:00:00 2001
From: Prasad Joshi <prasadjoshi.linux@gmail.com>
Date: Mon, 23 Jul 2012 10:32:11 +0530
Subject: logfs: query block device for number of pages to send with bio
The block device driver puts a limit on maximum number of pages that
can be sent with the bio. Not all block devices can handle
BIO_MAX_PAGES number of pages in bio. Specifically the virtio-blk
diriver limits it to 126. When the LogFS file system was excersized in
KVM, the following bug from do_virtblk_request() was observed
static void do_virtblk_request(struct request_queue *q)
{
....
....
while ((req = blk_peek_request(q)) != NULL) {
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
....
....
}
....
}
The patch fixes the problem by querring the maximum number of pages in
bio allowed from block device driver and then using those many pages
during submit_bio.
Signed-off-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
---
fs/logfs/dev_bdev.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
(limited to 'fs/logfs/dev_bdev.c')
diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
index ea29df36893..e784a217b50 100644
--- a/fs/logfs/dev_bdev.c
+++ b/fs/logfs/dev_bdev.c
@@ -96,12 +96,11 @@ static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
struct address_space *mapping = super->s_mapping_inode->i_mapping;
struct bio *bio;
struct page *page;
- struct request_queue *q = bdev_get_queue(sb->s_bdev);
- unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
+ unsigned int max_pages;
int i;
- if (max_pages > BIO_MAX_PAGES)
- max_pages = BIO_MAX_PAGES;
+ max_pages = min(nr_pages, (size_t) bio_get_nr_vecs(super->s_bdev));
+
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
@@ -191,12 +190,11 @@ static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
{
struct logfs_super *super = logfs_super(sb);
struct bio *bio;
- struct request_queue *q = bdev_get_queue(sb->s_bdev);
- unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
+ unsigned int max_pages;
int i;
- if (max_pages > BIO_MAX_PAGES)
- max_pages = BIO_MAX_PAGES;
+ max_pages = min(nr_pages, (size_t) bio_get_nr_vecs(super->s_bdev));
+
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
--
cgit v1.2.3-70-g09d2