| Message ID | 1351615413-9182-1-git-send-email-sprabhu@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 30 Oct 2012 16:43:33 +0000 Sachin Prabhu <sprabhu@redhat.com> wrote: > We do not need to lookup a hashed negative directory since we have > already revalidated it before and have found it to be fine. > > This also prevents a crash in cifs_lookup() when it attempts to rehash > the already hashed negative lookup dentry. > > The patch has been tested using the reproducer at > https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28 > > Cc: <stable@kernel.org> # 3.6.x > Reported-by: Vit Zahradka <vit.zahradka@tiscali.cz> > Signed-off-by: Sachin Prabhu <sprabhu@redhat.com> > --- > fs/cifs/dir.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c > index 7c0a812..e26d0a6 100644 > --- a/fs/cifs/dir.c > +++ b/fs/cifs/dir.c > @@ -398,6 +398,12 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry, > * in network traffic in the other paths. > */ > if (!(oflags & O_CREAT)) { > + /* Check for hashed negative dentry. We have already revalidated > + * the dentry and it is fine. No need to perform another lookup. > + */ > + if (!d_unhashed(direntry)) > + return -ENOENT; > + > struct dentry *res = cifs_lookup(inode, direntry, 0); > if (IS_ERR(res)) > return PTR_ERR(res); Acked-by: Jeff Layton <jlayton@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2012/10/30 Sachin Prabhu <sprabhu@redhat.com>: > We do not need to lookup a hashed negative directory since we have > already revalidated it before and have found it to be fine. > > This also prevents a crash in cifs_lookup() when it attempts to rehash > the already hashed negative lookup dentry. > > The patch has been tested using the reproducer at > https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28 > > Cc: <stable@kernel.org> # 3.6.x > Reported-by: Vit Zahradka <vit.zahradka@tiscali.cz> > Signed-off-by: Sachin Prabhu <sprabhu@redhat.com> > --- > fs/cifs/dir.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c > index 7c0a812..e26d0a6 100644 > --- a/fs/cifs/dir.c > +++ b/fs/cifs/dir.c > @@ -398,6 +398,12 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry, > * in network traffic in the other paths. > */ > if (!(oflags & O_CREAT)) { > + /* Check for hashed negative dentry. We have already revalidated > + * the dentry and it is fine. No need to perform another lookup. > + */ Patch looks ok, but the comment above doesn't match the kernel CodingStyle for block comments. While cifs code has a many places where it doesn't follow the style, we should keep new code as clean as possible. > + if (!d_unhashed(direntry)) > + return -ENOENT; > + > struct dentry *res = cifs_lookup(inode, direntry, 0); > if (IS_ERR(res)) > return PTR_ERR(res); > -- > 1.7.11.7 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-10-30 at 22:30 +0400, Pavel Shilovsky wrote: > > if (!(oflags & O_CREAT)) { > > + /* Check for hashed negative dentry. We have already > revalidated > > + * the dentry and it is fine. No need to perform > another lookup. > > + */ > > Patch looks ok, but the comment above doesn't match the kernel > CodingStyle for block comments. While cifs code has a many places > where it doesn't follow the style, we should keep new code as clean as > possible. Sorry about that. I had passed it through checkpatch.pl and it came out fine. I checked the codestyle document and it appears that this style is preferred only for files in net/ and drivers/net/. I am sending a v2 of the patch with the small cosmetic change to ensure that it follows the Coding Style. Sachin Prabhu -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c index 7c0a812..e26d0a6 100644 --- a/fs/cifs/dir.c +++ b/fs/cifs/dir.c @@ -398,6 +398,12 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry, * in network traffic in the other paths. */ if (!(oflags & O_CREAT)) { + /* Check for hashed negative dentry. We have already revalidated + * the dentry and it is fine. No need to perform another lookup. + */ + if (!d_unhashed(direntry)) + return -ENOENT; + struct dentry *res = cifs_lookup(inode, direntry, 0); if (IS_ERR(res)) return PTR_ERR(res);
We do not need to lookup a hashed negative directory since we have already revalidated it before and have found it to be fine. This also prevents a crash in cifs_lookup() when it attempts to rehash the already hashed negative lookup dentry. The patch has been tested using the reproducer at https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28 Cc: <stable@kernel.org> # 3.6.x Reported-by: Vit Zahradka <vit.zahradka@tiscali.cz> Signed-off-by: Sachin Prabhu <sprabhu@redhat.com> --- fs/cifs/dir.c | 6 ++++++ 1 file changed, 6 insertions(+)