From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-mtd@lists.infradead.org, Al Viro <viro@zeniv.linux.org.uk>,
linux-f2fs-devel@lists.sourceforge.net
Subject: [f2fs-dev] [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link
Date: Wed, 10 Apr 2019 13:21:14 -0700 [thread overview]
Message-ID: <20190410202115.64501-2-ebiggers@kernel.org> (raw)
In-Reply-To: <20190410202115.64501-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
Use 'READ_ONCE(inode->i_link)' to explicitly support filesystems caching
the symlink target in ->i_link later if it was unavailable at iget()
time, or wasn't easily available. I'll be doing this in fscrypt, to
improve the performance of encrypted symlinks on ext4, f2fs, and ubifs.
->i_link will start NULL and may later be set to a non-NULL value by a
smp_store_release() or cmpxchg_release(). READ_ONCE() is needed on the
read side. smp_load_acquire() is unnecessary because only a data
dependency barrier is required. (Thanks to Al for pointing this out.)
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/namei.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index dede0147b3f6e..2855de004c1a9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1066,7 +1066,7 @@ const char *get_link(struct nameidata *nd)
return ERR_PTR(error);
nd->last_type = LAST_BIND;
- res = inode->i_link;
+ res = READ_ONCE(inode->i_link);
if (!res) {
const char * (*get)(struct dentry *, struct inode *,
struct delayed_call *);
@@ -4729,7 +4729,7 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
spin_unlock(&inode->i_lock);
}
- link = inode->i_link;
+ link = READ_ONCE(inode->i_link);
if (!link) {
link = inode->i_op->get_link(dentry, inode, &done);
if (IS_ERR(link))
--
2.21.0.392.gf8f6787159e-goog
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
WARNING: multiple messages have this Message-ID (diff)
From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-mtd@lists.infradead.org, Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link
Date: Wed, 10 Apr 2019 13:21:14 -0700 [thread overview]
Message-ID: <20190410202115.64501-2-ebiggers@kernel.org> (raw)
In-Reply-To: <20190410202115.64501-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
Use 'READ_ONCE(inode->i_link)' to explicitly support filesystems caching
the symlink target in ->i_link later if it was unavailable at iget()
time, or wasn't easily available. I'll be doing this in fscrypt, to
improve the performance of encrypted symlinks on ext4, f2fs, and ubifs.
->i_link will start NULL and may later be set to a non-NULL value by a
smp_store_release() or cmpxchg_release(). READ_ONCE() is needed on the
read side. smp_load_acquire() is unnecessary because only a data
dependency barrier is required. (Thanks to Al for pointing this out.)
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/namei.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index dede0147b3f6e..2855de004c1a9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1066,7 +1066,7 @@ const char *get_link(struct nameidata *nd)
return ERR_PTR(error);
nd->last_type = LAST_BIND;
- res = inode->i_link;
+ res = READ_ONCE(inode->i_link);
if (!res) {
const char * (*get)(struct dentry *, struct inode *,
struct delayed_call *);
@@ -4729,7 +4729,7 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
spin_unlock(&inode->i_lock);
}
- link = inode->i_link;
+ link = READ_ONCE(inode->i_link);
if (!link) {
link = inode->i_op->get_link(dentry, inode, &done);
if (IS_ERR(link))
--
2.21.0.392.gf8f6787159e-goog
WARNING: multiple messages have this Message-ID (diff)
From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-mtd@lists.infradead.org, Al Viro <viro@zeniv.linux.org.uk>,
linux-f2fs-devel@lists.sourceforge.net
Subject: [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link
Date: Wed, 10 Apr 2019 13:21:14 -0700 [thread overview]
Message-ID: <20190410202115.64501-2-ebiggers@kernel.org> (raw)
In-Reply-To: <20190410202115.64501-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
Use 'READ_ONCE(inode->i_link)' to explicitly support filesystems caching
the symlink target in ->i_link later if it was unavailable at iget()
time, or wasn't easily available. I'll be doing this in fscrypt, to
improve the performance of encrypted symlinks on ext4, f2fs, and ubifs.
->i_link will start NULL and may later be set to a non-NULL value by a
smp_store_release() or cmpxchg_release(). READ_ONCE() is needed on the
read side. smp_load_acquire() is unnecessary because only a data
dependency barrier is required. (Thanks to Al for pointing this out.)
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/namei.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index dede0147b3f6e..2855de004c1a9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1066,7 +1066,7 @@ const char *get_link(struct nameidata *nd)
return ERR_PTR(error);
nd->last_type = LAST_BIND;
- res = inode->i_link;
+ res = READ_ONCE(inode->i_link);
if (!res) {
const char * (*get)(struct dentry *, struct inode *,
struct delayed_call *);
@@ -4729,7 +4729,7 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
spin_unlock(&inode->i_lock);
}
- link = inode->i_link;
+ link = READ_ONCE(inode->i_link);
if (!link) {
link = inode->i_op->get_link(dentry, inode, &done);
if (IS_ERR(link))
--
2.21.0.392.gf8f6787159e-goog
WARNING: multiple messages have this Message-ID (diff)
From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-mtd@lists.infradead.org, Al Viro <viro@zeniv.linux.org.uk>,
linux-f2fs-devel@lists.sourceforge.net
Subject: [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link
Date: Wed, 10 Apr 2019 13:21:14 -0700 [thread overview]
Message-ID: <20190410202115.64501-2-ebiggers@kernel.org> (raw)
In-Reply-To: <20190410202115.64501-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
Use 'READ_ONCE(inode->i_link)' to explicitly support filesystems caching
the symlink target in ->i_link later if it was unavailable at iget()
time, or wasn't easily available. I'll be doing this in fscrypt, to
improve the performance of encrypted symlinks on ext4, f2fs, and ubifs.
->i_link will start NULL and may later be set to a non-NULL value by a
smp_store_release() or cmpxchg_release(). READ_ONCE() is needed on the
read side. smp_load_acquire() is unnecessary because only a data
dependency barrier is required. (Thanks to Al for pointing this out.)
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/namei.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index dede0147b3f6e..2855de004c1a9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1066,7 +1066,7 @@ const char *get_link(struct nameidata *nd)
return ERR_PTR(error);
nd->last_type = LAST_BIND;
- res = inode->i_link;
+ res = READ_ONCE(inode->i_link);
if (!res) {
const char * (*get)(struct dentry *, struct inode *,
struct delayed_call *);
@@ -4729,7 +4729,7 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
spin_unlock(&inode->i_lock);
}
- link = inode->i_link;
+ link = READ_ONCE(inode->i_link);
if (!link) {
link = inode->i_op->get_link(dentry, inode, &done);
if (IS_ERR(link))
--
2.21.0.392.gf8f6787159e-goog
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2019-04-10 20:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 20:21 [PATCH v2 0/2] fscrypt: improve encrypted symlink performance Eric Biggers
2019-04-10 20:21 ` Eric Biggers
2019-04-10 20:21 ` Eric Biggers [this message]
2019-04-10 20:21 ` [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link Eric Biggers
2019-04-10 20:21 ` Eric Biggers
2019-04-10 20:21 ` Eric Biggers
2019-04-10 21:06 ` Al Viro
2019-04-10 21:06 ` Al Viro
2019-04-10 21:06 ` Al Viro
2019-04-10 23:15 ` Eric Biggers
2019-04-10 23:15 ` Eric Biggers
2019-04-10 23:15 ` Eric Biggers
2019-04-11 2:25 ` Al Viro
2019-04-11 2:25 ` Al Viro
2019-04-11 2:25 ` Al Viro
2019-04-11 17:28 ` Eric Biggers
2019-04-11 17:28 ` Eric Biggers
2019-04-17 16:41 ` Theodore Ts'o
2019-04-17 16:41 ` Theodore Ts'o
2019-04-17 16:41 ` Theodore Ts'o
2019-04-10 20:21 ` [PATCH v2 2/2] fscrypt: cache decrypted symlink target in ->i_link Eric Biggers
2019-04-10 20:21 ` Eric Biggers
2019-04-10 20:21 ` Eric Biggers
2019-04-17 16:55 ` Theodore Ts'o
2019-04-17 16:55 ` Theodore Ts'o
2019-04-17 16:55 ` Theodore Ts'o
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