[PATCH 1/1] fat: restore original value when fat_ent_write failed

[PATCH 1/1] fat: restore original value when fat_ent_write failed

[Ren Wei]

From: Yemu Lu <prcups@krgm.moe>

fat_ent_write() may have committed the new link to the primary FAT
but then failed on the mirror copy, leaving the chain pointing to
new_dclus even though the caller will free it. Restore the original
value to keep the chain consistent.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Yemu Lu <prcups@krgm.moe>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
---
 fs/fat/misc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 3027ef53af21..710e2e6aa1a5 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -133,7 +133,11 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 		ret = fat_ent_read(inode, &fatent, last);
 		if (ret >= 0) {
 			int wait = inode_needs_sync(inode);
+			int old = ret;
+
 			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
+			if (ret < 0)
+				fat_ent_write(inode, &fatent, old, wait);
 			fatent_brelse(&fatent);
 		}
 		if (ret < 0)
-- 
2.52.0

Re: [PATCH 1/1] fat: restore original value when fat_ent_write failed

[OGAWA Hirofumi]

Ren Wei <n05ec@lzu.edu.cn> writes:

> From: Yemu Lu <prcups@krgm.moe>
>
> fat_ent_write() may have committed the new link to the primary FAT
> but then failed on the mirror copy, leaving the chain pointing to
> new_dclus even though the caller will free it. Restore the original
> value to keep the chain consistent.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@kernel.org
> Reported-by: Yuan Tan <yuantan098@gmail.com>
> Reported-by: Yifan Wu <yifanwucs@gmail.com>
> Reported-by: Juefei Pu <tomapufckgml@gmail.com>
> Reported-by: Xin Liu <bird@lzu.edu.cn>
> Signed-off-by: Yemu Lu <prcups@krgm.moe>
> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>

Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

> ---
>  fs/fat/misc.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/fs/fat/misc.c b/fs/fat/misc.c
> index 3027ef53af21..710e2e6aa1a5 100644
> --- a/fs/fat/misc.c
> +++ b/fs/fat/misc.c
> @@ -133,7 +133,11 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
>  		ret = fat_ent_read(inode, &fatent, last);
>  		if (ret >= 0) {
>  			int wait = inode_needs_sync(inode);
> +			int old = ret;
> +
>  			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
> +			if (ret < 0)
> +				fat_ent_write(inode, &fatent, old, wait);
>  			fatent_brelse(&fatent);
>  		}
>  		if (ret < 0)

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>