* [RFC PATCH] ext4: use the normal helper to get the actual inode
@ 2020-10-10 8:10 xiakaixu1987
2020-10-12 9:33 ` Lukas Czerner
0 siblings, 1 reply; 3+ messages in thread
From: xiakaixu1987 @ 2020-10-10 8:10 UTC (permalink / raw)
To: linux-ext4; +Cc: tytso, adilger.kernel, Kaixu Xia
From: Kaixu Xia <kaixuxia@tencent.com>
Here we use the READ_ONCE to fix race conditions in ->d_compare() and
->d_hash() when they are called in RCU-walk mode, seems we can use
the normal helper d_inode_rcu() to get the actual inode.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
---
fs/ext4/dir.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 1d82336b1cd4..3bf6cb8e55f6 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -674,7 +674,7 @@ static int ext4_d_compare(const struct dentry *dentry, unsigned int len,
{
struct qstr qstr = {.name = str, .len = len };
const struct dentry *parent = READ_ONCE(dentry->d_parent);
- const struct inode *inode = READ_ONCE(parent->d_inode);
+ const struct inode *inode = d_inode_rcu(parent);
char strbuf[DNAME_INLINE_LEN];
if (!inode || !IS_CASEFOLDED(inode) ||
@@ -706,7 +706,7 @@ static int ext4_d_hash(const struct dentry *dentry, struct qstr *str)
{
const struct ext4_sb_info *sbi = EXT4_SB(dentry->d_sb);
const struct unicode_map *um = sbi->s_encoding;
- const struct inode *inode = READ_ONCE(dentry->d_inode);
+ const struct inode *inode = d_inode_rcu(dentry);
unsigned char *norm;
int len, ret = 0;
--
2.20.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [RFC PATCH] ext4: use the normal helper to get the actual inode
2020-10-10 8:10 [RFC PATCH] ext4: use the normal helper to get the actual inode xiakaixu1987
@ 2020-10-12 9:33 ` Lukas Czerner
2020-10-14 15:48 ` Theodore Y. Ts'o
0 siblings, 1 reply; 3+ messages in thread
From: Lukas Czerner @ 2020-10-12 9:33 UTC (permalink / raw)
To: xiakaixu1987; +Cc: linux-ext4, tytso, adilger.kernel, Kaixu Xia
On Sat, Oct 10, 2020 at 04:10:16PM +0800, xiakaixu1987@gmail.com wrote:
> From: Kaixu Xia <kaixuxia@tencent.com>
>
> Here we use the READ_ONCE to fix race conditions in ->d_compare() and
> ->d_hash() when they are called in RCU-walk mode, seems we can use
> the normal helper d_inode_rcu() to get the actual inode.
Looks good to me.
Thanks!
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
>
> Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
> ---
> fs/ext4/dir.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
> index 1d82336b1cd4..3bf6cb8e55f6 100644
> --- a/fs/ext4/dir.c
> +++ b/fs/ext4/dir.c
> @@ -674,7 +674,7 @@ static int ext4_d_compare(const struct dentry *dentry, unsigned int len,
> {
> struct qstr qstr = {.name = str, .len = len };
> const struct dentry *parent = READ_ONCE(dentry->d_parent);
> - const struct inode *inode = READ_ONCE(parent->d_inode);
> + const struct inode *inode = d_inode_rcu(parent);
> char strbuf[DNAME_INLINE_LEN];
>
> if (!inode || !IS_CASEFOLDED(inode) ||
> @@ -706,7 +706,7 @@ static int ext4_d_hash(const struct dentry *dentry, struct qstr *str)
> {
> const struct ext4_sb_info *sbi = EXT4_SB(dentry->d_sb);
> const struct unicode_map *um = sbi->s_encoding;
> - const struct inode *inode = READ_ONCE(dentry->d_inode);
> + const struct inode *inode = d_inode_rcu(dentry);
> unsigned char *norm;
> int len, ret = 0;
>
> --
> 2.20.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [RFC PATCH] ext4: use the normal helper to get the actual inode
2020-10-12 9:33 ` Lukas Czerner
@ 2020-10-14 15:48 ` Theodore Y. Ts'o
0 siblings, 0 replies; 3+ messages in thread
From: Theodore Y. Ts'o @ 2020-10-14 15:48 UTC (permalink / raw)
To: Lukas Czerner; +Cc: xiakaixu1987, linux-ext4, adilger.kernel, Kaixu Xia
On Mon, Oct 12, 2020 at 11:33:04AM +0200, Lukas Czerner wrote:
> On Sat, Oct 10, 2020 at 04:10:16PM +0800, xiakaixu1987@gmail.com wrote:
> > From: Kaixu Xia <kaixuxia@tencent.com>
> >
> > Here we use the READ_ONCE to fix race conditions in ->d_compare() and
> > ->d_hash() when they are called in RCU-walk mode, seems we can use
> > the normal helper d_inode_rcu() to get the actual inode.
>
> Looks good to me.
> Thanks!
>
> Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Thanks, applied.
- Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-10-14 15:50 UTC | newest]
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2020-10-12 9:33 ` Lukas Czerner
2020-10-14 15:48 ` Theodore Y. Ts'o
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