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Subject[PATCH 6/7] Handle case for invalid backing swap
Currently, we crash (issue BUG_ON) if backing swap
disk size is zero. This can happen is user specified
an extended partition or simply a bad disk as backing
swap. A crash is really an unpleasant surprise to user
for such trivial problems.

Now, we check for this condition and simply fail device
initialization if this is the case.

Additional cleanups:
* use static for all functions
* remove extra newline between functions
* memset backing_swap_name to NULL on device reset

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
---
drivers/staging/ramzswap/ramzswap_drv.c | 16 +++++++++++-----
1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/ramzswap/ramzswap_drv.c b/drivers/staging/ramzswap/ramzswap_drv.c
index 7e0a3fa..1bca069 100644
--- a/drivers/staging/ramzswap/ramzswap_drv.c
+++ b/drivers/staging/ramzswap/ramzswap_drv.c
@@ -220,7 +220,7 @@ out:
return ret;
}

-void ramzswap_ioctl_get_stats(struct ramzswap *rzs,
+static void ramzswap_ioctl_get_stats(struct ramzswap *rzs,
struct ramzswap_ioctl_stats *s)
{
strncpy(s->backing_swap_name, rzs->backing_swap_name,
@@ -502,6 +502,14 @@ static int setup_backing_swap(struct ramzswap *rzs)
goto bad_param;
}
disksize = i_size_read(inode);
+ /*
+ * Can happen if user gives an extended partition as
+ * backing swap or simply a bad disk.
+ */
+ if (!disksize) {
+ pr_err("Error reading backing swap size.\n");
+ goto bad_param;
+ }
} else if (S_ISREG(inode->i_mode)) {
bdev = inode->i_sb->s_bdev;
if (IS_SWAPFILE(inode)) {
@@ -519,7 +527,6 @@ static int setup_backing_swap(struct ramzswap *rzs)
rzs->swap_file = swap_file;
rzs->backing_swap = bdev;
rzs->disksize = disksize;
- BUG_ON(!rzs->disksize);

return 0;

@@ -537,7 +544,7 @@ out:
* Map logical page number 'pagenum' to physical page number
* on backing swap device. For block device, this is a nop.
*/
-u32 map_backing_swap_page(struct ramzswap *rzs, u32 pagenum)
+static u32 map_backing_swap_page(struct ramzswap *rzs, u32 pagenum)
{
u32 skip_pages, entries_per_page;
size_t delta, se_offset, skipped;
@@ -668,7 +675,6 @@ static int handle_uncompressed_page(struct ramzswap *rzs, struct bio *bio)
return 0;
}

-
/*
* Called when request page is not present in ramzswap.
* Its either in backing swap device (if present) or
@@ -936,7 +942,6 @@ out:
return 0;
}

-
/*
* Check if request is within bounds and page aligned.
*/
@@ -1064,6 +1069,7 @@ static void reset_device(struct ramzswap *rzs)
bd_release(rzs->backing_swap);
filp_close(rzs->swap_file, NULL);
rzs->backing_swap = NULL;
+ memset(rzs->backing_swap_name, 0, MAX_SWAP_NAME_LEN);
}

/* Reset stats */
--
1.6.2.5



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