* [PATCH] vfs: call d_op->d_prune() before unhashing dentry
@ 2013-08-13 7:42 Yan, Zheng
2013-08-22 5:10 ` Sage Weil
0 siblings, 1 reply; 3+ messages in thread
From: Yan, Zheng @ 2013-08-13 7:42 UTC (permalink / raw)
To: viro, sage; +Cc: linux-fsdevel, Yan, Zheng
From: "Yan, Zheng" <zheng.z.yan@intel.com>
The d_prune dentry operation is used to notify filesystem when VFS
about to prune a hashed dentry from the dcache. There are three
code paths that prune dentries: shrink_dcache_for_umount_subtree(),
prune_dcache_sb() and d_prune_aliases(). For the d_prune_aliases()
case, VFS unhashes the dentry first, then call the d_prune dentry
operation. This confuses ceph_d_prune() (ceph uses the d_prune
dentry operation to maintain a flag indicating whether the complete
contents of a directory are in the dcache, pruning unhashed dentry
does not affect dir's completeness)
This patch fixes the issue by calling the d_prune dentry operation
in d_prune_aliases(), before unhashing the dentry. Also make VFS
only call the d_prune dentry operation for hashed dentry, to avoid
calling the d_prune dentry operation twice when dentry is pruned
by d_prune_aliases().
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
fs/dcache.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 87bdb53..612e99b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -472,7 +472,7 @@ relock:
* inform the fs via d_prune that this dentry is about to be
* unhashed and destroyed.
*/
- if (dentry->d_flags & DCACHE_OP_PRUNE)
+ if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry))
dentry->d_op->d_prune(dentry);
dentry_lru_del(dentry);
@@ -719,6 +719,14 @@ restart:
hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
spin_lock(&dentry->d_lock);
if (!dentry->d_count) {
+ /*
+ * inform the fs via d_prune that this dentry
+ * is about to be unhashed and destroyed.
+ */
+ if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
+ !d_unhashed(dentry))
+ dentry->d_op->d_prune(dentry);
+
__dget_dlock(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
@@ -907,7 +915,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
* inform the fs that this dentry is about to be
* unhashed and destroyed.
*/
- if (dentry->d_flags & DCACHE_OP_PRUNE)
+ if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
+ !d_unhashed(dentry))
dentry->d_op->d_prune(dentry);
dentry_lru_del(dentry);
--
1.8.1.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] vfs: call d_op->d_prune() before unhashing dentry
2013-08-13 7:42 [PATCH] vfs: call d_op->d_prune() before unhashing dentry Yan, Zheng
@ 2013-08-22 5:10 ` Sage Weil
2013-09-03 15:58 ` Sage Weil
0 siblings, 1 reply; 3+ messages in thread
From: Sage Weil @ 2013-08-22 5:10 UTC (permalink / raw)
To: viro, Yan, Zheng; +Cc: linux-fsdevel
On Tue, 13 Aug 2013, Yan, Zheng wrote:
> From: "Yan, Zheng" <zheng.z.yan@intel.com>
>
> The d_prune dentry operation is used to notify filesystem when VFS
> about to prune a hashed dentry from the dcache. There are three
> code paths that prune dentries: shrink_dcache_for_umount_subtree(),
> prune_dcache_sb() and d_prune_aliases(). For the d_prune_aliases()
> case, VFS unhashes the dentry first, then call the d_prune dentry
> operation. This confuses ceph_d_prune() (ceph uses the d_prune
> dentry operation to maintain a flag indicating whether the complete
> contents of a directory are in the dcache, pruning unhashed dentry
> does not affect dir's completeness)
>
> This patch fixes the issue by calling the d_prune dentry operation
> in d_prune_aliases(), before unhashing the dentry. Also make VFS
> only call the d_prune dentry operation for hashed dentry, to avoid
> calling the d_prune dentry operation twice when dentry is pruned
> by d_prune_aliases().
>
> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This is behaving well under my testing, seems to resolve the race we were
encoutering before, and cleans up the d_prune semantics nicely IMO.
Al, does this look okay to you?
Thanks!
sage
> ---
> fs/dcache.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 87bdb53..612e99b 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -472,7 +472,7 @@ relock:
> * inform the fs via d_prune that this dentry is about to be
> * unhashed and destroyed.
> */
> - if (dentry->d_flags & DCACHE_OP_PRUNE)
> + if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry))
> dentry->d_op->d_prune(dentry);
>
> dentry_lru_del(dentry);
> @@ -719,6 +719,14 @@ restart:
> hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
> spin_lock(&dentry->d_lock);
> if (!dentry->d_count) {
> + /*
> + * inform the fs via d_prune that this dentry
> + * is about to be unhashed and destroyed.
> + */
> + if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
> + !d_unhashed(dentry))
> + dentry->d_op->d_prune(dentry);
> +
> __dget_dlock(dentry);
> __d_drop(dentry);
> spin_unlock(&dentry->d_lock);
> @@ -907,7 +915,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
> * inform the fs that this dentry is about to be
> * unhashed and destroyed.
> */
> - if (dentry->d_flags & DCACHE_OP_PRUNE)
> + if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
> + !d_unhashed(dentry))
> dentry->d_op->d_prune(dentry);
>
> dentry_lru_del(dentry);
> --
> 1.8.1.4
>
> --
> 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
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] vfs: call d_op->d_prune() before unhashing dentry
2013-08-22 5:10 ` Sage Weil
@ 2013-09-03 15:58 ` Sage Weil
0 siblings, 0 replies; 3+ messages in thread
From: Sage Weil @ 2013-09-03 15:58 UTC (permalink / raw)
To: viro; +Cc: Yan, Zheng, linux-fsdevel, hch
Hi Al,
We'd like to get this into mainline during this window. Does this patch
look good to you?
Thanks-
sage
On Wed, 21 Aug 2013, Sage Weil wrote:
> On Tue, 13 Aug 2013, Yan, Zheng wrote:
> > From: "Yan, Zheng" <zheng.z.yan@intel.com>
> >
> > The d_prune dentry operation is used to notify filesystem when VFS
> > about to prune a hashed dentry from the dcache. There are three
> > code paths that prune dentries: shrink_dcache_for_umount_subtree(),
> > prune_dcache_sb() and d_prune_aliases(). For the d_prune_aliases()
> > case, VFS unhashes the dentry first, then call the d_prune dentry
> > operation. This confuses ceph_d_prune() (ceph uses the d_prune
> > dentry operation to maintain a flag indicating whether the complete
> > contents of a directory are in the dcache, pruning unhashed dentry
> > does not affect dir's completeness)
> >
> > This patch fixes the issue by calling the d_prune dentry operation
> > in d_prune_aliases(), before unhashing the dentry. Also make VFS
> > only call the d_prune dentry operation for hashed dentry, to avoid
> > calling the d_prune dentry operation twice when dentry is pruned
> > by d_prune_aliases().
> >
> > Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
>
> Reviewed-by: Sage Weil <sage@inktank.com>
>
> This is behaving well under my testing, seems to resolve the race we were
> encoutering before, and cleans up the d_prune semantics nicely IMO.
>
> Al, does this look okay to you?
>
> Thanks!
> sage
>
> > ---
> > fs/dcache.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/dcache.c b/fs/dcache.c
> > index 87bdb53..612e99b 100644
> > --- a/fs/dcache.c
> > +++ b/fs/dcache.c
> > @@ -472,7 +472,7 @@ relock:
> > * inform the fs via d_prune that this dentry is about to be
> > * unhashed and destroyed.
> > */
> > - if (dentry->d_flags & DCACHE_OP_PRUNE)
> > + if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry))
> > dentry->d_op->d_prune(dentry);
> >
> > dentry_lru_del(dentry);
> > @@ -719,6 +719,14 @@ restart:
> > hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
> > spin_lock(&dentry->d_lock);
> > if (!dentry->d_count) {
> > + /*
> > + * inform the fs via d_prune that this dentry
> > + * is about to be unhashed and destroyed.
> > + */
> > + if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
> > + !d_unhashed(dentry))
> > + dentry->d_op->d_prune(dentry);
> > +
> > __dget_dlock(dentry);
> > __d_drop(dentry);
> > spin_unlock(&dentry->d_lock);
> > @@ -907,7 +915,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
> > * inform the fs that this dentry is about to be
> > * unhashed and destroyed.
> > */
> > - if (dentry->d_flags & DCACHE_OP_PRUNE)
> > + if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
> > + !d_unhashed(dentry))
> > dentry->d_op->d_prune(dentry);
> >
> > dentry_lru_del(dentry);
> > --
> > 1.8.1.4
> >
> > --
> > 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 linux-fsdevel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-08-13 7:42 [PATCH] vfs: call d_op->d_prune() before unhashing dentry Yan, Zheng
2013-08-22 5:10 ` Sage Weil
2013-09-03 15:58 ` Sage Weil
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