| Message ID | 1394115376-17109-1-git-send-email-zheng.z.yan@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mar 6, 2014, at 9:16, Yan, Zheng <zheng.z.yan@intel.com> wrote: > From: David Howells <dhowells@redhat.com> > > Make __d_materialise_dentry() set the materialised dentry name correctly by > flipping the arguments to switch_names(). > > switch_names() is lazy: if both names are internal to their dentries, it'll > overwrite that of the first dentry with that of the second, and won't update > that of the second. > > In the case of __d_materialise_dentry(), the second is an already extant > anonymous dentry that we want to insert into the tree in place of the dentry we > just looked up[*]. However, the dentry we just looked up carries the name we > actually want to use. > > [*] This is used by NFS to join a mount of a subtree into a mount of a tree > nearer the root when the two meet, where both mounts share a superblock and > thus a set of dentries. > > Signed-off-by: David Howells <dhowells@redhat.com> > --- > fs/dcache.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/dcache.c b/fs/dcache.c > index 265e0ce..ff779d4 100644 > --- a/fs/dcache.c > +++ b/fs/dcache.c > @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) > > dparent = dentry->d_parent; > > - switch_names(dentry, anon); > + switch_names(anon, dentry); > swap(dentry->d_name.hash, anon->d_name.hash); > > dentry->d_parent = dentry; Well spotted... We ought to better document the fact that ’switch_names’ is asymmetrical. Perhaps change it to ‘update_target_name’, and then switch the argument names so that the ’target’ really is the thing that gets updated?
On Thu, Mar 06, 2014 at 09:35:01AM -0500, Trond Myklebust wrote: > > On Mar 6, 2014, at 9:16, Yan, Zheng <zheng.z.yan@intel.com> wrote: > > > From: David Howells <dhowells@redhat.com> > > > > Make __d_materialise_dentry() set the materialised dentry name correctly by > > flipping the arguments to switch_names(). > > > > switch_names() is lazy: if both names are internal to their dentries, it'll > > overwrite that of the first dentry with that of the second, and won't update > > that of the second. > > > > In the case of __d_materialise_dentry(), the second is an already extant > > anonymous dentry that we want to insert into the tree in place of the dentry we > > just looked up[*]. However, the dentry we just looked up carries the name we > > actually want to use. > > > > [*] This is used by NFS to join a mount of a subtree into a mount of a tree > > nearer the root when the two meet, where both mounts share a superblock and > > thus a set of dentries. > > > > Signed-off-by: David Howells <dhowells@redhat.com> > > --- > > fs/dcache.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/dcache.c b/fs/dcache.c > > index 265e0ce..ff779d4 100644 > > --- a/fs/dcache.c > > +++ b/fs/dcache.c > > @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) > > > > dparent = dentry->d_parent; > > > > - switch_names(dentry, anon); > > + switch_names(anon, dentry); > > swap(dentry->d_name.hash, anon->d_name.hash); > > > > dentry->d_parent = dentry; > > Well spotted... > > We ought to better document the fact that ’switch_names’ is asymmetrical. Perhaps change it to ‘update_target_name’, and then switch the argument names so that the ’target’ really is the thing that gets updated? Probably not worth it if Miklos's RENAME_EXCHANGE operation is making it symmetrical soon anyway?: http://mid.gmane.org/<1380643239-16060-4-git-send-email-miklos@szeredi.hu> --b. -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Mar 07, 2014 at 01:55:52PM -0500, J. Bruce Fields wrote: > On Thu, Mar 06, 2014 at 09:35:01AM -0500, Trond Myklebust wrote: > > > > On Mar 6, 2014, at 9:16, Yan, Zheng <zheng.z.yan@intel.com> wrote: > > > > > From: David Howells <dhowells@redhat.com> > > > > > > Make __d_materialise_dentry() set the materialised dentry name correctly by > > > flipping the arguments to switch_names(). > > > > > > switch_names() is lazy: if both names are internal to their dentries, it'll > > > overwrite that of the first dentry with that of the second, and won't update > > > that of the second. > > > > > > In the case of __d_materialise_dentry(), the second is an already extant > > > anonymous dentry that we want to insert into the tree in place of the dentry we > > > just looked up[*]. However, the dentry we just looked up carries the name we > > > actually want to use. > > > > > > [*] This is used by NFS to join a mount of a subtree into a mount of a tree > > > nearer the root when the two meet, where both mounts share a superblock and > > > thus a set of dentries. > > > > > > Signed-off-by: David Howells <dhowells@redhat.com> > > > --- > > > fs/dcache.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/fs/dcache.c b/fs/dcache.c > > > index 265e0ce..ff779d4 100644 > > > --- a/fs/dcache.c > > > +++ b/fs/dcache.c > > > @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) > > > > > > dparent = dentry->d_parent; > > > > > > - switch_names(dentry, anon); > > > + switch_names(anon, dentry); > > > swap(dentry->d_name.hash, anon->d_name.hash); > > > > > > dentry->d_parent = dentry; > > > > Well spotted... > > > > We ought to better document the fact that ’switch_names’ is asymmetrical. Perhaps change it to ‘update_target_name’, and then switch the argument names so that the ’target’ really is the thing that gets updated? > > Probably not worth it if Miklos's RENAME_EXCHANGE operation is making it > symmetrical soon anyway?: > > http://mid.gmane.org/<1380643239-16060-4-git-send-email-miklos@szeredi.hu> To clarify: I mean, the suggested cleanup may not be worth it. The __d_materialise_dentry bugfix of course is. (What I wonder about is the duplication between this and __d_move. Is there any way to make d_materialise_unique a special case of d_move?) --b. -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Al, Could you include this in 3.15 Regards Yan, Zheng On 03/06/2014 10:35 PM, Trond Myklebust wrote: > > On Mar 6, 2014, at 9:16, Yan, Zheng <zheng.z.yan@intel.com> wrote: > >> From: David Howells <dhowells@redhat.com> >> >> Make __d_materialise_dentry() set the materialised dentry name correctly by >> flipping the arguments to switch_names(). >> >> switch_names() is lazy: if both names are internal to their dentries, it'll >> overwrite that of the first dentry with that of the second, and won't update >> that of the second. >> >> In the case of __d_materialise_dentry(), the second is an already extant >> anonymous dentry that we want to insert into the tree in place of the dentry we >> just looked up[*]. However, the dentry we just looked up carries the name we >> actually want to use. >> >> [*] This is used by NFS to join a mount of a subtree into a mount of a tree >> nearer the root when the two meet, where both mounts share a superblock and >> thus a set of dentries. >> >> Signed-off-by: David Howells <dhowells@redhat.com> >> --- >> fs/dcache.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/dcache.c b/fs/dcache.c >> index 265e0ce..ff779d4 100644 >> --- a/fs/dcache.c >> +++ b/fs/dcache.c >> @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) >> >> dparent = dentry->d_parent; >> >> - switch_names(dentry, anon); >> + switch_names(anon, dentry); >> swap(dentry->d_name.hash, anon->d_name.hash); >> >> dentry->d_parent = dentry; > > Well spotted... > > We ought to better document the fact that ’switch_names’ is asymmetrical. Perhaps change it to ‘update_target_name’, and then switch the argument names so that the ’target’ really is the thing that gets updated? > > _________________________________ > Trond Myklebust > Linux NFS client maintainer, PrimaryData > trond.myklebust@primarydata.com > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Al, Can this go to Linus via your tree? Thanks! sage On Mon, 31 Mar 2014, Yan, Zheng wrote: > Hi Al, > > Could you include this in 3.15 > > Regards > Yan, Zheng > > On 03/06/2014 10:35 PM, Trond Myklebust wrote: > > > > On Mar 6, 2014, at 9:16, Yan, Zheng <zheng.z.yan@intel.com> wrote: > > > >> From: David Howells <dhowells@redhat.com> > >> > >> Make __d_materialise_dentry() set the materialised dentry name correctly by > >> flipping the arguments to switch_names(). > >> > >> switch_names() is lazy: if both names are internal to their dentries, it'll > >> overwrite that of the first dentry with that of the second, and won't update > >> that of the second. > >> > >> In the case of __d_materialise_dentry(), the second is an already extant > >> anonymous dentry that we want to insert into the tree in place of the dentry we > >> just looked up[*]. However, the dentry we just looked up carries the name we > >> actually want to use. > >> > >> [*] This is used by NFS to join a mount of a subtree into a mount of a tree > >> nearer the root when the two meet, where both mounts share a superblock and > >> thus a set of dentries. > >> > >> Signed-off-by: David Howells <dhowells@redhat.com> > >> --- > >> fs/dcache.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/fs/dcache.c b/fs/dcache.c > >> index 265e0ce..ff779d4 100644 > >> --- a/fs/dcache.c > >> +++ b/fs/dcache.c > >> @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) > >> > >> dparent = dentry->d_parent; > >> > >> - switch_names(dentry, anon); > >> + switch_names(anon, dentry); > >> swap(dentry->d_name.hash, anon->d_name.hash); > >> > >> dentry->d_parent = dentry; > > > > Well spotted... > > > > We ought to better document the fact that ?switch_names? is asymmetrical. Perhaps change it to ?update_target_name?, and then switch the argument names so that the ?target? really is the thing that gets updated? > > > > _________________________________ > > Trond Myklebust > > Linux NFS client maintainer, PrimaryData > > trond.myklebust@primarydata.com > > > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Apr 07, 2014 at 06:56:28AM -0700, Sage Weil wrote: > Hi Al, > > Can this go to Linus via your tree? I believe this has been fixed by da1ce0670c14d8380e423a3239e562a1dc15fa9e "vfs: add cross-rename". Though probably the patch should still go in, possibly with a changelog update. We want it for stable kernels if nothing else. --b. > > Thanks! > sage > > > On Mon, 31 Mar 2014, Yan, Zheng wrote: > > > Hi Al, > > > > Could you include this in 3.15 > > > > Regards > > Yan, Zheng > > > > On 03/06/2014 10:35 PM, Trond Myklebust wrote: > > > > > > On Mar 6, 2014, at 9:16, Yan, Zheng <zheng.z.yan@intel.com> wrote: > > > > > >> From: David Howells <dhowells@redhat.com> > > >> > > >> Make __d_materialise_dentry() set the materialised dentry name correctly by > > >> flipping the arguments to switch_names(). > > >> > > >> switch_names() is lazy: if both names are internal to their dentries, it'll > > >> overwrite that of the first dentry with that of the second, and won't update > > >> that of the second. > > >> > > >> In the case of __d_materialise_dentry(), the second is an already extant > > >> anonymous dentry that we want to insert into the tree in place of the dentry we > > >> just looked up[*]. However, the dentry we just looked up carries the name we > > >> actually want to use. > > >> > > >> [*] This is used by NFS to join a mount of a subtree into a mount of a tree > > >> nearer the root when the two meet, where both mounts share a superblock and > > >> thus a set of dentries. > > >> > > >> Signed-off-by: David Howells <dhowells@redhat.com> > > >> --- > > >> fs/dcache.c | 2 +- > > >> 1 file changed, 1 insertion(+), 1 deletion(-) > > >> > > >> diff --git a/fs/dcache.c b/fs/dcache.c > > >> index 265e0ce..ff779d4 100644 > > >> --- a/fs/dcache.c > > >> +++ b/fs/dcache.c > > >> @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) > > >> > > >> dparent = dentry->d_parent; > > >> > > >> - switch_names(dentry, anon); > > >> + switch_names(anon, dentry); > > >> swap(dentry->d_name.hash, anon->d_name.hash); > > >> > > >> dentry->d_parent = dentry; > > > > > > Well spotted... > > > > > > We ought to better document the fact that ?switch_names? is asymmetrical. Perhaps change it to ?update_target_name?, and then switch the argument names so that the ?target? really is the thing that gets updated? > > > > > > _________________________________ > > > Trond Myklebust > > > Linux NFS client maintainer, PrimaryData > > > trond.myklebust@primarydata.com > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" 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/dcache.c b/fs/dcache.c index 265e0ce..ff779d4 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2698,7 +2698,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) dparent = dentry->d_parent; - switch_names(dentry, anon); + switch_names(anon, dentry); swap(dentry->d_name.hash, anon->d_name.hash); dentry->d_parent = dentry;