ceph: persistent caching with fscache

fs/fscache/cookie.c +5 -0

+bool __fscache_check_consistency(struct fscache_cookie *cookie)
+{
+	struct fscache_object *object;
+
+	if (cookie->def->type != FSCACHE_COOKIE_TYPE_DATAFILE)

Quoted 5 lines · Hongyi Jia

fs/fscache/cookie.c +5 -0

+bool __fscache_check_consistency(struct fscache_cookie *cookie)
+{
+     struct fscache_object *object;
+
+     if (cookie->def->type != FSCACHE_COOKIE_TYPE_DATAFILE)

fs/fscache/cookie.c void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire) · line 554

Quoted 10 lines

fs/fscache/cookie.c +10 -0

+             return false;
+
+     if (hlist_empty(&cookie->backing_objects))
+             return false;
+
+     object = hlist_entry(cookie->backing_objects.first,
+                     struct fscache_object, cookie_link);
+
+     return object->cache->ops->check_consistency(object);
+}

Hmmm... This isn't actually safe. You have to either:

(1) hold cookie->lock whilst touching the object pointer when coming from the netfs side, or:

(2) set up an operation to do this (as, say, __fscache_alloc_page() does).

The problem is that you have nothing to defend against the object being withdrawn by the cache under you.

David

If the cache is withdrawn and we're starting anew I would consider that to okay. I would consider an empty page cache for a cookie to be consistent since there's nothing stale that I can read. Unless there's another synchronization issue that I'm missing in fscache.

Quoted 4 lines · Milosz Tanski

If the cache is withdrawn and we're starting anew I would consider that to okay. I would consider an empty page cache for a cookie to be consistent since there's nothing stale that I can read. Unless there's another synchronization issue that I'm missing in fscache.

The problem is that the fscache_object struct may be deallocated whilst you're using it.

David

Is it as simple as stick a mutex at the top of the __fscache_check_consistency function before we try to find the object?

Quoted 2 lines · Milosz Tanski

Is it as simple as stick a mutex at the top of the __fscache_check_consistency function before we try to find the object?

You can lock a mutex in a function, but where are you actually going to place the mutex struct? And what other code is going to take it? To do this, you'd have to place the mutex struct in fscache_cookie. The problem is that you have to protect the pointer from fscache_cookie to fscache_object - so placing the mutex in fscache_object doesn't help.

Quoted 10 lines · David Howells

Quoted 2 lines · Milosz Tanski

Is it as simple as stick a mutex at the top of the __fscache_check_consistency function before we try to find the object?

You can lock a mutex in a function, but where are you actually going to place the mutex struct? And what other code is going to take it? To do this, you'd have to place the mutex struct in fscache_cookie. The problem is that you have to protect the pointer from fscache_cookie to fscache_object - so placing the mutex in fscache_object doesn't help.

David,

I meant lock cookie->lock inside of __fscache_check_consistency in the beginning of the function. I don't see the need to push this into the netfs code.

- Milosz

Adding support for fscache to the Ceph filesystem. This would bring it to on par with some of the other network filesystems in Linux (like NFS, AFS, etc...)

In order to mount the filesystem with fscache the 'fsc' mount option must be passed.

Signed-off-by Milosz Tanski <[email protected]>

---
 fs/ceph/Kconfig  |   9 ++
 fs/ceph/Makefile |   2 +
 fs/ceph/addr.c   |  37 +++++--
 fs/ceph/cache.c  | 311 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/ceph/cache.h  | 123 ++++++++++++++++++++++
 fs/ceph/caps.c   |  19 +++-
 fs/ceph/file.c   |  17 +++
 fs/ceph/inode.c  |  66 +++++++++++-
 fs/ceph/super.c  |  47 ++++++++-
 fs/ceph/super.h  |  17 +++
 10 files changed, 636 insertions(+), 12 deletions(-)
 create mode 100644 fs/ceph/cache.c
 create mode 100644 fs/ceph/cache.h

fs/ceph/Kconfig +9 -0

index 49bc782..ac9a2ef 100644
@@ -16,3 +16,12 @@ config CEPH_FS
 
 	  If unsure, say N.
 
+if CEPH_FS
+config CEPH_FSCACHE
+	bool "Enable Ceph client caching support"
+	depends on CEPH_FS=m && FSCACHE || CEPH_FS=y && FSCACHE=y
+	help
+	  Choose Y here to enable persistent, read-only local
+	  caching support for Ceph clients using FS-Cache
+
+endif

fs/ceph/Makefile +2 -0

index bd35212..0af0678 100644
@@ -9,3 +9,5 @@ ceph-y := super.o inode.o dir.o file.o locks.o addr.o ioctl.o \
 	mds_client.o mdsmap.o strings.o ceph_frag.o \
 	debugfs.o
 
+ceph-$(CONFIG_CEPH_FSCACHE) += cache.o
+

fs/ceph/addr.c +31 -6

index cb78ce8..632bb48 100644
@@ -11,6 +11,7 @@
 
 #include "super.h"
 #include "mds_client.h"
+#include "cache.h"
 #include <linux/ceph/osd_client.h>
 
 /*

@@ -159,6 +160,11 @@ static void ceph_invalidatepage(struct page *page, unsigned int offset,
 		return;
 	}
 
+	ceph_invalidate_fscache_page(inode, page);
+
+	if (!PagePrivate(page))
+		return;
+
 	/*
 	 * We can get non-dirty pages here due to races between
 	 * set_page_dirty and truncate_complete_page; just spit out a

@@ -178,14 +184,17 @@ static void ceph_invalidatepage(struct page *page, unsigned int offset,
 	ClearPagePrivate(page);
 }
 
-/* just a sanity check */
 static int ceph_releasepage(struct page *page, gfp_t g)
 {
 	struct inode *inode = page->mapping ? page->mapping->host : NULL;
 	dout("%p releasepage %p idx %lu\n", inode, page, page->index);
 	WARN_ON(PageDirty(page));
-	WARN_ON(PagePrivate(page));
-	return 0;
+
+	/* Can we release the page from the cache? */
+	if (!ceph_release_fscache_page(page, g))
+		return 0;
+
+	return !PagePrivate(page);
 }
 
 /*

@@ -195,11 +204,16 @@ static int readpage_nounlock(struct file *filp, struct page *page)
 {
 	struct inode *inode = file_inode(filp);
 	struct ceph_inode_info *ci = ceph_inode(inode);
-	struct ceph_osd_client *osdc = 
+	struct ceph_osd_client *osdc =
 		&ceph_inode_to_client(inode)->client->osdc;
 	int err = 0;
 	u64 len = PAGE_CACHE_SIZE;
 
+	err = ceph_readpage_from_fscache(inode, page);
+
+	if (err == 0)
+		goto out;
+
 	dout("readpage inode %p file %p page %p index %lu\n",
 	     inode, filp, page, page->index);
 	err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,

@@ -217,6 +231,9 @@ static int readpage_nounlock(struct file *filp, struct page *page)
 	}
 	SetPageUptodate(page);
 
+	if (err == 0)
+		ceph_readpage_to_fscache(inode, page);
+
 out:
 	return err < 0 ? err : 0;
 }

@@ -259,6 +276,7 @@ static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
 		     page->index);
 		flush_dcache_page(page);
 		SetPageUptodate(page);
+		ceph_readpage_to_fscache(inode, page);
 		unlock_page(page);
 		page_cache_release(page);
 		bytes -= PAGE_CACHE_SIZE;

@@ -328,7 +346,7 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 		page = list_entry(page_list->prev, struct page, lru);
 		BUG_ON(PageLocked(page));
 		list_del(&page->lru);
-		
+
  		dout("start_read %p adding %p idx %lu\n", inode, page,
 		     page->index);
 		if (add_to_page_cache_lru(page, &inode->i_data, page->index,

@@ -375,6 +393,12 @@ static int ceph_readpages(struct file *file, struct address_space *mapping,
 	int rc = 0;
 	int max = 0;
 
+	rc = ceph_readpages_from_fscache(mapping->host, mapping, page_list,
+					 &nr_pages);
+
+	if (rc == 0)
+		goto out;
+
 	if (fsc->mount_options->rsize >= PAGE_CACHE_SIZE)
 		max = (fsc->mount_options->rsize + PAGE_CACHE_SIZE - 1)
 			>> PAGE_SHIFT;

@@ -494,6 +518,8 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 	    CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
 		set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
 
+	ceph_readpage_to_fscache(inode, page);
+
 	set_page_writeback(page);
 	err = ceph_osdc_writepages(osdc, ceph_vino(inode),
 				   &ci->i_layout, snapc,

@@ -549,7 +575,6 @@ static void ceph_release_pages(struct page **pages, int num)
 	pagevec_release(&pvec);
 }
 
-
 /*
  * async writeback completion handler.
  *

fs/ceph/cache.c new file +311 -0

new file mode 100644
index 0000000..a5ad9c3
@@ -0,0 +1,311 @@
+/*
+ * Ceph cache definitions.
+ *
+ *  Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
+ *  Written by Milosz Tanski ([email protected])
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to:
+ *  Free Software Foundation
+ *  51 Franklin Street, Fifth Floor
+ *  Boston, MA  02111-1301  USA
+ *
+ */
+
+#include "super.h"
+#include "cache.h"
+
+struct ceph_aux_inode {
+	struct timespec	mtime;
+	loff_t          size;
+};
+
+struct fscache_netfs ceph_cache_netfs = {
+	.name		= "ceph",
+	.version	= 0,
+};
+
+static uint16_t ceph_fscache_session_get_key(const void *cookie_netfs_data,
+					     void *buffer, uint16_t maxbuf)
+{
+	const struct ceph_fs_client* fsc = cookie_netfs_data;
+	uint16_t klen;
+
+	klen = sizeof(fsc->client->fsid);
+	if (klen > maxbuf)
+		return 0;
+
+	memcpy(buffer, &fsc->client->fsid, klen);
+	return klen;
+}
+
+static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
+	.name		= "CEPH.fsid",
+	.type		= FSCACHE_COOKIE_TYPE_INDEX,
+	.get_key	= ceph_fscache_session_get_key,
+};
+
+void ceph_fscache_register_fsid_cookie(struct ceph_fs_client* fsc)
+{
+	fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
+					      &ceph_fscache_fsid_object_def,
+					      fsc);
+}
+
+void ceph_fscache_unregister_fsid_cookie(struct ceph_fs_client* fsc)
+{
+	fscache_relinquish_cookie(fsc->fscache, 0);
+	fsc->fscache = NULL;
+}
+
+static uint16_t ceph_fscache_inode_get_key(const void *cookie_netfs_data,
+					   void *buffer, uint16_t maxbuf)
+{
+	const struct ceph_inode_info* ci = cookie_netfs_data;
+	uint16_t klen;
+
+	/* use ceph virtual inode (id + snaphot) */
+	klen = sizeof(ci->i_vino);
+	if (klen > maxbuf)
+		return 0;
+
+	memcpy(buffer, &ci->i_vino, klen);
+	return klen;
+}
+
+static uint16_t ceph_fscache_inode_get_aux(const void *cookie_netfs_data,
+					   void *buffer, uint16_t bufmax)
+{
+	struct ceph_aux_inode aux;
+	const struct ceph_inode_info* ci = cookie_netfs_data;
+	const struct inode* inode = &ci->vfs_inode;
+
+	memset(&aux, 0, sizeof(aux));
+	aux.mtime = inode->i_mtime;
+	aux.size = inode->i_size;
+
+	memcpy(buffer, &aux, sizeof(aux));
+
+	return sizeof(aux);
+}
+
+static void ceph_fscache_inode_get_attr(const void *cookie_netfs_data,
+					uint64_t *size)
+{
+	const struct ceph_inode_info* ci = cookie_netfs_data;
+	const struct inode* inode = &ci->vfs_inode;
+
+	*size = inode->i_size;
+}
+
+static enum fscache_checkaux ceph_fscache_inode_check_aux(
+	void *cookie_netfs_data, const void *data, uint16_t dlen)
+{
+	struct ceph_aux_inode aux;
+	struct ceph_inode_info* ci = cookie_netfs_data;
+	struct inode* inode = &ci->vfs_inode;
+
+	if (dlen != sizeof(aux))
+		return FSCACHE_CHECKAUX_OBSOLETE;
+
+	memset(&aux, 0, sizeof(aux));
+	aux.mtime = inode->i_mtime;
+	aux.size = inode->i_size;
+
+	if (memcmp(data, &aux, sizeof(aux)) != 0)
+		return FSCACHE_CHECKAUX_OBSOLETE;
+
+	dout("ceph inode 0x%p cached okay", ci);
+	return FSCACHE_CHECKAUX_OKAY;
+}
+
+static void ceph_fscache_inode_now_uncached(void* cookie_netfs_data)
+{
+	struct ceph_inode_info* ci = cookie_netfs_data;
+	struct pagevec pvec;
+	pgoff_t first;
+	int loop, nr_pages;
+
+	pagevec_init(&pvec, 0);
+	first = 0;
+
+	dout("ceph inode 0x%p now uncached", ci);
+
+	while (1) {
+		nr_pages = pagevec_lookup(&pvec, ci->vfs_inode.i_mapping, first,
+					  PAGEVEC_SIZE - pagevec_count(&pvec));
+
+		if (!nr_pages)
+			break;
+
+		for (loop = 0; loop < nr_pages; loop++)
+			ClearPageFsCache(pvec.pages[loop]);
+
+		first = pvec.pages[nr_pages - 1]->index + 1;
+
+		pvec.nr = nr_pages;
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+}
+
+static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
+	.name		= "CEPH.inode",
+	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
+	.get_key	= ceph_fscache_inode_get_key,
+	.get_attr	= ceph_fscache_inode_get_attr,
+	.get_aux	= ceph_fscache_inode_get_aux,
+	.check_aux	= ceph_fscache_inode_check_aux,
+	.now_uncached	= ceph_fscache_inode_now_uncached,
+};
+
+void ceph_fscache_register_inode_cookie(struct ceph_fs_client* fsc,
+					struct ceph_inode_info* ci)
+{
+	struct inode* inode = &ci->vfs_inode;
+
+	/* No caching for filesystem */
+	if (fsc->fscache == NULL)
+		return;
+
+	/* Only cache for regular files that are read only */
+	if ((ci->vfs_inode.i_mode & S_IFREG) == 0)
+		return;
+
+	/* Avoid multiple racing open requests */
+	mutex_lock(&inode->i_mutex);
+
+	if (ci->fscache)
+		goto done;
+
+	ci->fscache = fscache_acquire_cookie(fsc->fscache,
+					     &ceph_fscache_inode_object_def,
+					     ci);
+done:
+	mutex_unlock(&inode->i_mutex);
+
+}
+
+void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
+{
+	struct fscache_cookie* cookie;
+
+	if ((cookie = ci->fscache) == NULL)
+		return;
+
+	ci->fscache = NULL;
+
+	fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
+	fscache_relinquish_cookie(cookie, 0);
+}
+
+static void ceph_vfs_readpage_complete(struct page *page, void *data, int error)
+{
+	if (!error)
+		SetPageUptodate(page);
+}
+
+static void ceph_vfs_readpage_complete_unlock(struct page *page, void *data, int error)
+{
+	if (!error)
+		SetPageUptodate(page);
+
+	unlock_page(page);
+}
+
+static inline int cache_valid(struct ceph_inode_info *ci)
+{
+	return ((ceph_caps_issued(ci) & CEPH_CAP_FILE_CACHE) &&
+		(ci->i_fscache_gen == ci->i_rdcache_gen));
+}
+
+
+/* Atempt to read from the fscache,
+ *
+ * This function is called from the readpage_nounlock context. DO NOT attempt to
+ * unlock the page here (or in the callback).
+ */
+int __ceph_readpage_from_fscache(struct inode *inode, struct page *page)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	int ret;
+
+	if (!cache_valid(ci))
+		return -ENOBUFS;
+
+	ret = fscache_read_or_alloc_page(ci->fscache, page,
+					 ceph_vfs_readpage_complete, NULL,
+					 GFP_KERNEL);
+
+	switch (ret) {
+		case 0: /* Page found */
+			dout("page read submitted\n");
+			return 0;
+		case -ENOBUFS: /* Pages were not found, and can't be */
+		case -ENODATA: /* Pages were not found */
+			dout("page/inode not in cache\n");
+			return ret;
+		default:
+			dout("%s: unknown error ret = %i\n", __func__, ret);
+			return ret;
+	}
+}
+
+int __ceph_readpages_from_fscache(struct inode *inode,
+				  struct address_space *mapping,
+				  struct list_head *pages,
+				  unsigned *nr_pages)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	int ret;
+
+	if (!cache_valid(ci))
+		return -ENOBUFS;
+
+	ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
+					  ceph_vfs_readpage_complete_unlock,
+					  NULL, mapping_gfp_mask(mapping));
+
+	switch (ret) {
+		case 0: /* All pages found */
+			dout("all-page read submitted\n");
+			return 0;
+		case -ENOBUFS: /* Some pages were not found, and can't be */
+		case -ENODATA: /* some pages were not found */
+			dout("page/inode not in cache\n");
+			return ret;
+		default:
+			dout("%s: unknown error ret = %i\n", __func__, ret);
+			return ret;
+	}
+}
+
+void __ceph_readpage_to_fscache(struct inode *inode, struct page *page)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	int ret;
+
+	if (!cache_valid(ci))
+		return;
+
+	ret = fscache_write_page(ci->fscache, page, GFP_KERNEL);
+	if (ret)
+		 fscache_uncache_page(ci->fscache, page);
+}
+
+void __ceph_invalidate_fscache_page(struct inode* inode, struct page *page)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+
+	fscache_wait_on_page_write(ci->fscache, page);
+	fscache_uncache_page(ci->fscache, page);
+}

fs/ceph/cache.h new file +35 -0

new file mode 100644
index 0000000..23f2666
@@ -0,0 +1,123 @@
+/*
+ * Ceph cache definitions.
+ *
+ *  Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
+ *  Written by Milosz Tanski ([email protected])
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to:
+ *  Free Software Foundation
+ *  51 Franklin Street, Fifth Floor
+ *  Boston, MA  02111-1301  USA
+ *
+ */
+
+#ifndef _CEPH_CACHE_H
+#define _CEPH_CACHE_H
+
+#include <linux/fscache.h>
+
+
+extern struct fscache_netfs ceph_cache_netfs;
+
+
+void ceph_fscache_register_fsid_cookie(struct ceph_fs_client* fsc);
+void ceph_fscache_unregister_fsid_cookie(struct ceph_fs_client* fsc);
+void ceph_fscache_register_inode_cookie(struct ceph_fs_client* parent_fsc,

fs/ceph/cache.h new file +78 -0

+
+#ifdef CONFIG_CEPH_FSCACHE
+
+
+static inline int ceph_readpage_from_fscache(struct inode* inode,
+					     struct page *page)
+{
+	return __ceph_readpage_from_fscache(inode, page);
+}
+
+static inline int ceph_readpages_from_fscache(struct inode *inode,
+					      struct address_space *mapping,
+					      struct list_head *pages,
+					      unsigned *nr_pages)
+{
+	return __ceph_readpages_from_fscache(inode, mapping, pages,
+					     nr_pages);
+}
+
+static inline void ceph_readpage_to_fscache(struct inode *inode,
+					    struct page *page)
+{
+	return __ceph_readpage_to_fscache(inode, page);
+}
+
+static inline void ceph_invalidate_fscache_page(struct inode *inode,
+						struct page *page)
+{
+	return __ceph_invalidate_fscache_page(inode, page);
+}
+
+static inline int ceph_release_fscache_page(struct page *page, gfp_t gfp)
+{
+	struct inode* inode = page->mapping->host;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	return fscache_maybe_release_page(ci->fscache, page, gfp);
+}
+
+#else
+
+static inline int ceph_readpage_from_fscache(struct inode* inode,
+					     struct page *page)
+{
+	return -ENOBUFS;
+}
+
+static inline int ceph_readpages_from_fscache(struct inode *inode,
+					      struct address_space *mapping,
+					      struct list_head *pages,
+					      unsigned *nr_pages)
+{
+	return -ENOBUFS;
+}
+
+static inline void ceph_readpage_to_fscache(struct inode *inode,
+					    struct page *page)
+{
+}
+
+static inline void ceph_invalidate_fscache_page(struct inode *inode,
+						struct page *page)
+{
+}
+
+static inline int ceph_release_fscache_page(struct page *page, gfp_t gfp)
+{
+	return 1;
+}
+
+static void ceph_fscache_readpages_cancel(struct inode *inode,
+					  struct list_head *pages)
+{
+
+}
+
+#endif
+
+#endif

fs/ceph/caps.c +14 -1

index 5a26bc1..a94ca4b 100644
@@ -10,6 +10,7 @@
 
 #include "super.h"
 #include "mds_client.h"
+#include "cache.h"
 #include <linux/ceph/decode.h>
 #include <linux/ceph/messenger.h>
 

@@ -479,8 +480,9 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
 	 * i_rdcache_gen.
 	 */
 	if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) &&
-	    (had & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
+	    (had & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0) {
 		ci->i_rdcache_gen++;
+	}
 
 	/*
 	 * if we are newly issued FILE_SHARED, mark dir not complete; we

@@ -2395,6 +2397,7 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 	int writeback = 0;
 	int queue_invalidate = 0;
 	int deleted_inode = 0;
+	int queue_revalidate = 0;
 
 	dout("handle_cap_grant inode %p cap %p mds%d seq %d %s\n",
 	     inode, cap, mds, seq, ceph_cap_string(newcaps));

@@ -2417,6 +2420,8 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 				ci->i_rdcache_revoking = ci->i_rdcache_gen;
 			}
 		}
+
+		fscache_invalidate(ci->fscache);
 	}
 
 	/* side effects now are allowed */

@@ -2458,6 +2463,11 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 		}
 	}
 
+	/* Do we need to revalidate our fscache cookie. Don't bother on the
+	 * first cache cap as we already validate at cookie creation time. */
+	if ((issued & CEPH_CAP_FILE_CACHE) && ci->i_rdcache_gen > 1)
+		queue_revalidate = 1;
+
 	/* size/ctime/mtime/atime? */
 	ceph_fill_file_size(inode, issued,
 			    le32_to_cpu(grant->truncate_seq),

@@ -2542,6 +2552,7 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 	BUG_ON(cap->issued & ~cap->implemented);
 
 	spin_unlock(&ci->i_ceph_lock);
+
 	if (writeback)
 		/*
 		 * queue inode for writeback: we can't actually call

@@ -2553,6 +2564,8 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 		ceph_queue_invalidate(inode);
 	if (deleted_inode)
 		invalidate_aliases(inode);
+	if (queue_revalidate)
+		ceph_queue_revalidate(inode);
 	if (wake)
 		wake_up_all(&ci->i_cap_wq);
 

fs/ceph/caps.c +1 -0

+	}
 }
 
 /*

fs/ceph/file.c +17 -0

index 68af489..b81c75f 100644
@@ -12,6 +12,7 @@
 
 #include "super.h"
 #include "mds_client.h"
+#include "cache.h"
 
 /*
  * Ceph file operations

@@ -69,9 +70,23 @@ static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
 {
 	struct ceph_file_info *cf;
 	int ret = 0;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
+	struct ceph_mds_client *mdsc = fsc->mdsc;
 
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFREG:
+		/* First file open request creates the cookie, we want to keep
+		 * this cookie around for the filetime of the inode as not to
+		 * have to worry about fscache register / revoke / operation
+		 * races.
+		 *
+		 * Also, if we know the operation is going to invalidate data
+		 * (non readonly) just nuke the cache right away.
+		 */
+		ceph_fscache_register_inode_cookie(mdsc->fsc, ci);
+		if ((fmode & CEPH_FILE_MODE_WR))
+			fscache_invalidate(ci->fscache);
 	case S_IFDIR:
 		dout("init_file %p %p 0%o (regular)\n", inode, file,
 		     inode->i_mode);

@@ -182,6 +197,7 @@ int ceph_open(struct inode *inode, struct file *file)
 		spin_unlock(&ci->i_ceph_lock);
 		return ceph_init_file(inode, file, fmode);
 	}
+
 	spin_unlock(&ci->i_ceph_lock);
 
 	dout("open fmode %d wants %s\n", fmode, ceph_cap_string(wanted));

@@ -192,6 +208,7 @@ int ceph_open(struct inode *inode, struct file *file)
 	}
 	req->r_inode = inode;
 	ihold(inode);
+
 	req->r_num_caps = 1;
 	if (flags & (O_CREAT|O_TRUNC))
 		parent_inode = ceph_get_dentry_parent_inode(file->f_dentry);

fs/ceph/inode.c +1 -0

index 602ccd8..5daf7f8 100644
@@ -12,6 +12,7 @@
 
 #include "super.h"
 #include "mds_client.h"
+#include "cache.h"
 #include <linux/ceph/decode.h>
 
 /*

fs/ceph/inode.c +52 -2

 /*
  * find or create an inode, given the ceph ino number

@@ -386,6 +388,13 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 
 	INIT_WORK(&ci->i_vmtruncate_work, ceph_vmtruncate_work);
 
+#ifdef CONFIG_CEPH_FSCACHE
+	ci->fscache = NULL;
+	/* The first load is verifed cookie open time */
+	ci->i_fscache_gen = 1;
+	INIT_WORK(&ci->i_revalidate_work, ceph_revalidate_work);
+#endif
+
 	return &ci->vfs_inode;
 }
 

@@ -405,6 +414,8 @@ void ceph_destroy_inode(struct inode *inode)
 
 	dout("destroy_inode %p ino %llx.%llx\n", inode, ceph_vinop(inode));
 
+	ceph_fscache_unregister_inode_cookie(ci);
+
 	ceph_queue_caps_release(inode);
 
 	/*

@@ -439,7 +450,6 @@ void ceph_destroy_inode(struct inode *inode)
 	call_rcu(&inode->i_rcu, ceph_i_callback);
 }
 
-
 /*
  * Helpers to fill in size, ctime, mtime, and atime.  We have to be
  * careful because either the client or MDS may have more up to date

@@ -491,6 +501,10 @@ int ceph_fill_file_size(struct inode *inode, int issued,
 		     truncate_size);
 		ci->i_truncate_size = truncate_size;
 	}
+
+	if (queue_trunc)
+		fscache_invalidate(ci->fscache);
+
 	return queue_trunc;
 }
 

@@ -1079,7 +1093,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
 			 * complete.
 			 */
 			ceph_set_dentry_offset(req->r_old_dentry);
-			dout("dn %p gets new offset %lld\n", req->r_old_dentry, 
+			dout("dn %p gets new offset %lld\n", req->r_old_dentry,
 			     ceph_dentry(req->r_old_dentry)->offset);
 
 			dn = req->r_old_dentry;  /* use old_dentry */

@@ -1494,6 +1508,7 @@ void ceph_queue_vmtruncate(struct inode *inode)
 	struct ceph_inode_info *ci = ceph_inode(inode);
 
 	ihold(inode);
+
 	if (queue_work(ceph_sb_to_client(inode->i_sb)->trunc_wq,
 		       &ci->i_vmtruncate_work)) {
 		dout("ceph_queue_vmtruncate %p\n", inode);

@@ -1565,6 +1580,53 @@ retry:
 	wake_up_all(&ci->i_cap_wq);
 }
 
+static void ceph_revalidate_work(struct work_struct *work)
+{
+	int issued;
+	u32 orig_gen;
+	struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
+						  i_revalidate_work);
+	struct inode *inode = &ci->vfs_inode;
+
+	spin_lock(&ci->i_ceph_lock);
+	issued = __ceph_caps_issued(ci, NULL);
+	orig_gen = ci->i_rdcache_gen;
+	spin_unlock(&ci->i_ceph_lock);
+
+	if (!(issued & CEPH_CAP_FILE_CACHE)) {
+		dout("revalidate_work lost cache before validation %p\n",
+		     inode);
+		goto out;
+	}
+
+	if (!fscache_check_consistency(ci->fscache))
+		fscache_invalidate(ci->fscache);
+
+	spin_lock(&ci->i_ceph_lock);
+	/* Update the new valid generation (backwards sanity check too) */
+	if (orig_gen > ci->i_fscache_gen) {
+		ci->i_fscache_gen = orig_gen;
+	}
+	spin_unlock(&ci->i_ceph_lock);
+
+out:
+	iput(&ci->vfs_inode);
+}
+
+void ceph_queue_revalidate(struct inode *inode)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+

fs/ceph/inode.c +0 -0

 /*
  * symlinks

fs/ceph/super.c +15 -0

index 6627b26..a56baab 100644
@@ -17,6 +17,7 @@
 
 #include "super.h"
 #include "mds_client.h"
+#include "cache.h"
 
 #include <linux/ceph/ceph_features.h>
 #include <linux/ceph/decode.h>

@@ -142,6 +143,8 @@ enum {
 	Opt_nodcache,
 	Opt_ino32,
 	Opt_noino32,
+	Opt_fscache,
+	Opt_nofscache
 };
 
 static match_table_t fsopt_tokens = {

@@ -167,6 +170,8 @@ static match_table_t fsopt_tokens = {
 	{Opt_nodcache, "nodcache"},
 	{Opt_ino32, "ino32"},
 	{Opt_noino32, "noino32"},
+	{Opt_fscache, "fsc"},
+	{Opt_nofscache, "nofsc"},
 	{-1, NULL}
 };
 

@@ -260,6 +265,12 @@ static int parse_fsopt_token(char *c, void *private)
 	case Opt_noino32:
 		fsopt->flags &= ~CEPH_MOUNT_OPT_INO32;
 		break;
+	case Opt_fscache:
+		fsopt->flags |= CEPH_MOUNT_OPT_FSCACHE;
+		break;
+	case Opt_nofscache:
+		fsopt->flags &= ~CEPH_MOUNT_OPT_FSCACHE;
+		break;
 	default:
 		BUG_ON(token);
 	}

@@ -422,6 +433,10 @@ static int ceph_show_options(struct seq_file *m, struct dentry *root)
 		seq_puts(m, ",dcache");
 	else
 		seq_puts(m, ",nodcache");
+	if (fsopt->flags & CEPH_MOUNT_OPT_FSCACHE)
+		seq_puts(m, ",fsc");
+	else
+		seq_puts(m, ",nofsc");
 
 	if (fsopt->wsize)
 		seq_printf(m, ",wsize=%d", fsopt->wsize);

@@ -530,11 +545,24 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
 	if (!fsc->wb_pagevec_pool)
 		goto fail_trunc_wq;

fs/ceph/super.c +4 -0

 	/* caps */
 	fsc->min_caps = fsopt->max_readdir;
 
 	return fsc;
 
+#ifdef CONFIG_CEPH_FSCACHE
+fail_fscache:
+	ceph_fscache_unregister_fsid_cookie(fsc);
+#endif
 fail_trunc_wq:
 	destroy_workqueue(fsc->trunc_wq);
 fail_pg_inv_wq:

fs/ceph/super.c +2 -0

 	destroy_workqueue(fsc->wb_wq);
 	destroy_workqueue(fsc->pg_inv_wq);
 	destroy_workqueue(fsc->trunc_wq);

@@ -588,6 +620,8 @@ static void ceph_inode_init_once(void *foo)
 
 static int __init init_caches(void)
 {
+	int error = -ENOMEM;
+
 	ceph_inode_cachep = kmem_cache_create("ceph_inode_info",
 				      sizeof(struct ceph_inode_info),
 				      __alignof__(struct ceph_inode_info),

fs/ceph/super.c +2 -1

+	return 0;
 bad_file:
 	kmem_cache_destroy(ceph_dentry_cachep);
 bad_dentry:
 	kmem_cache_destroy(ceph_cap_cachep);
 bad_cap:
 	kmem_cache_destroy(ceph_inode_cachep);
-	return -ENOMEM;
+	return error;
 }
 
 static void destroy_caches(void)

@@ -629,10 +667,15 @@ static void destroy_caches(void)
 	 * destroy cache.
 	 */

fs/ceph/super.c +0 -0

 }
 
 

fs/ceph/super.h +17 -0

index f1e4e47..72eac24 100644
@@ -16,6 +16,10 @@
 
 #include <linux/ceph/libceph.h>
 
+#ifdef CONFIG_CEPH_FSCACHE
+#include <linux/fscache.h>
+#endif
+
 /* f_type in struct statfs */
 #define CEPH_SUPER_MAGIC 0x00c36400
 

@@ -29,6 +33,7 @@
 #define CEPH_MOUNT_OPT_NOASYNCREADDIR  (1<<7) /* no dcache readdir */
 #define CEPH_MOUNT_OPT_INO32           (1<<8) /* 32 bit inos */
 #define CEPH_MOUNT_OPT_DCACHE          (1<<9) /* use dcache for readdir etc */
+#define CEPH_MOUNT_OPT_FSCACHE         (1<<10) /* use fscache */
 
 #define CEPH_MOUNT_OPT_DEFAULT    (CEPH_MOUNT_OPT_RBYTES)
 

@@ -90,6 +95,11 @@ struct ceph_fs_client {
 	struct dentry *debugfs_bdi;
 	struct dentry *debugfs_mdsc, *debugfs_mdsmap;
 #endif
+
+#ifdef CONFIG_CEPH_FSCACHE
+	struct fscache_cookie *fscache;
+	struct workqueue_struct *revalidate_wq;
+#endif
 };
 
 

@@ -320,6 +330,12 @@ struct ceph_inode_info {
 
 	struct work_struct i_vmtruncate_work;
 
+#ifdef CONFIG_CEPH_FSCACHE
+	struct fscache_cookie *fscache;
+	u32 i_fscache_gen; /* sequence, for delayed fscache validate */
+	struct work_struct i_revalidate_work;
+#endif
+
 	struct inode vfs_inode; /* at end */
 };
 

@@ -700,6 +716,7 @@ extern void ceph_queue_vmtruncate(struct inode *inode);
 
 extern void ceph_queue_invalidate(struct inode *inode);
 extern void ceph_queue_writeback(struct inode *inode);
+extern void ceph_queue_revalidate(struct inode *inode);
 
 extern int ceph_do_getattr(struct inode *inode, int mask);
 extern int ceph_permission(struct inode *inode, int mask);

Signature · 6 lines

1.8.1.2

--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Currently the fscache code expect the netfs to call fscache_readpages_or_alloc inside the aops readpages callback. It marks all the pages in the list provided by readahead with PgPrivate2. In the cases that the netfs fails to read all the pages (which is legal) it ends up returning to the readahead and triggering a BUG. This happens because the page list still contains marked pages.

This patch implements a simple fscache_readpages_cancel function that the netfs should call before returning from readpages. It will revoke the pages from the underlying cache backend and unmark them.

This addresses this BUG being triggered by netfs code:

[12410647.597278] BUG: Bad page state in process petabucket  pfn:3d504e
[12410647.597292] page:ffffea000f541380 count:0 mapcount:0 mapping:
        (null) index:0x0
[12410647.597298] page flags: 0x200000000001000(private_2)

...

[12410647.597334] Call Trace:
[12410647.597345]  [<ffffffff815523f2>] dump_stack+0x19/0x1b
[12410647.597356]  [<ffffffff8111def7>] bad_page+0xc7/0x120
[12410647.597359]  [<ffffffff8111e49e>] free_pages_prepare+0x10e/0x120
[12410647.597361]  [<ffffffff8111fc80>] free_hot_cold_page+0x40/0x170
[12410647.597363]  [<ffffffff81123507>] __put_single_page+0x27/0x30
[12410647.597365]  [<ffffffff81123df5>] put_page+0x25/0x40
[12410647.597376]  [<ffffffffa02bdcf9>] ceph_readpages+0x2e9/0x6e0 [ceph]
[12410647.597379]  [<ffffffff81122a8f>] __do_page_cache_readahead+0x1af/0x260
[12410647.597382]  [<ffffffff81122ea1>] ra_submit+0x21/0x30
[12410647.597384]  [<ffffffff81118f64>] filemap_fault+0x254/0x490
[12410647.597387]  [<ffffffff8113a74f>] __do_fault+0x6f/0x4e0
[12410647.597391]  [<ffffffff810125bd>] ? __switch_to+0x16d/0x4a0
[12410647.597395]  [<ffffffff810865ba>] ? finish_task_switch+0x5a/0xc0
[12410647.597398]  [<ffffffff8113d856>] handle_pte_fault+0xf6/0x930
[12410647.597401]  [<ffffffff81008c33>] ? pte_mfn_to_pfn+0x93/0x110
[12410647.597403]  [<ffffffff81008cce>] ? xen_pmd_val+0xe/0x10
[12410647.597405]  [<ffffffff81005469>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e
[12410647.597407]  [<ffffffff8113f361>] handle_mm_fault+0x251/0x370
[12410647.597411]  [<ffffffff812b0ac4>] ? call_rwsem_down_read_failed+0x14/0x30
[12410647.597414]  [<ffffffff8155bffa>] __do_page_fault+0x1aa/0x550
[12410647.597418]  [<ffffffff8108011d>] ? up_write+0x1d/0x20
[12410647.597422]  [<ffffffff8113141c>] ? vm_mmap_pgoff+0xbc/0xe0
[12410647.597425]  [<ffffffff81143bb8>] ? SyS_mmap_pgoff+0xd8/0x240
[12410647.597427]  [<ffffffff8155c3ae>] do_page_fault+0xe/0x10
[12410647.597431]  [<ffffffff81558818>] page_fault+0x28/0x30

Signed-off-by Milosz Tanski <[email protected]>

---
 fs/fscache/page.c       | 16 ++++++++++++++++
 include/linux/fscache.h | 22 ++++++++++++++++++++++
 2 files changed, 38 insertions(+)

fs/fscache/page.c +16 -0

index d479ab3..0cc3153 100644
@@ -1132,3 +1132,19 @@ void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
        _leave("");
 }
 EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);
+
+/**
+ * Unmark pages allocate in the readahead code path (via:
+ * fscache_readpages_or_alloc) after delegating to the base filesystem
+ */
+void __fscache_readpages_cancel(struct fscache_cookie *cookie,
+                               struct list_head *pages)
+{
+       struct page *page;
+
+       list_for_each_entry(page, pages, lru) {
+               if (PageFsCache(page))
+                       __fscache_uncache_page(cookie, page);
+       }
+}
+EXPORT_SYMBOL(__fscache_readpages_cancel);

include/linux/fscache.h +22 -1

index 7a49e8f..c324177 100644
@@ -209,6 +209,8 @@ extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
                                         gfp_t);
 extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
                                              struct inode *);
+extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
+                                      struct list_head *pages);
 
 /**
  * fscache_register_netfs - Register a filesystem as desiring caching services

@@ -719,4 +721,24 @@ void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
                __fscache_uncache_all_inode_pages(cookie, inode);
 }
 
+/**
+ * fscache_readpages_cancel
+ * @cookie: The cookie representing the inode's cache object.
+ * @pages: The netfs pages that we canceled write on in readpages()
+ *
+ * Uncache/unreserve the pages reserved earlier in readpages() via
+ * fscache_readpages_or_alloc(). In most successful caches in readpages() this
+ * doesn't do anything. In cases when the underlying netfs's readahead failed
+ * we need to cleanup the pagelist (unmark and uncache).
+ *
+ * This function may sleep (if it's calling to the cache backend).
+ */
+static inline
+void fscache_readpages_cancel(struct fscache_cookie *cookie,
+                             struct list_head *pages)
+{
+       if (fscache_cookie_valid(cookie))
+               __fscache_readpages_cancel(cookie, pages);
+}
+
 #endif /* _LINUX_FSCACHE_H */
--

1.8.1.2

This an updated version of the fscache support for the Ceph filesystem. What's changed since the last patchset:

1. Sparater the readpages refactor into it's own patches. These were already accepted into the testing branch.

2. Tracked down the BUG in readahead cleanup code. We were returning with pages marked as private_2 from readpages(). I added a simple convenience function to the fscache netfs interface for cleaning up the page list at the end of asop readpages(). I know other filesystems (NFS) have ran into that since I've seen a few similar traces in Google search and the cachefs mailig list. The second patch new make Ceph use this interface.

I've been running this code (minus the BUG fix) on clients for a couple weeks with moderate 24/7 use without issues. At this point in time I feel like it's solid enough to go into the ceph kclient.

Please pull the code from my repository:
https://bitbucket.org/adfin/linux-fs.git branch: wip-ceph-fscache

The first two patches I included were not written by me but were written by Hongyi Jia. He implemented the cookie re-validation scheme into fscache core.

Finally, I CCed a couple other mailing lists (fsdevel, nfs) because the new fscache_readpages_cancel() should be used by other filesystems to avoid the same problem.

Hongyi Jia (2):
new cachefiles interface to check cache consistency new fscache interface to check cache consistency

Milosz Tanski (3):
ceph: use fscache as a local presisent cache
fscache: netfs function for cleanup post readpages
ceph: clean PgPrivate2 on returning from readpages

 fs/cachefiles/interface.c     |  19 +++
 fs/cachefiles/internal.h      |   1 +
 fs/cachefiles/xattr.c         |  39 ++++++
 fs/ceph/Kconfig               |   9 ++
 fs/ceph/Makefile              |   2 +
 fs/ceph/addr.c                |  39 +++++-
 fs/ceph/cache.c               | 311 ++++++++++++++++++++++++++++++++++++++++++
 fs/ceph/cache.h               | 130 ++++++++++++++++++
 fs/ceph/caps.c                |  19 ++-
 fs/ceph/file.c                |  17 +++
 fs/ceph/inode.c               |  66 ++++++++-
 fs/ceph/super.c               |  47 ++++++-

 fs/ceph/super.h               |  17 +++
 fs/fscache/cookie.c           |  22 +++
 fs/fscache/page.c             |  16 +++
 include/linux/fscache-cache.h |   4 +
 include/linux/fscache.h       |  39 ++++++
 17 files changed, 785 insertions(+), 12 deletions(-)
 create mode 100644 fs/ceph/cache.c
 create mode 100644 fs/ceph/cache.h

Signature · 1 line

1.8.1.2

Hi Milosz,

I've pulled this into the ceph testing branch to make sure it holds up in qa.

David, are the fscache patches here ready for the next merge window? Do you have a preference for whose tree they go through?

Thanks!
sage

Quoted 62 lines · Milosz Tanski

This an updated version of the fscache support for the Ceph filesystem. What's changed since the last patchset:

1. Sparater the readpages refactor into it's own patches. These were already accepted into the testing branch.

2. Tracked down the BUG in readahead cleanup code. We were returning with pages marked as private_2 from readpages(). I added a simple convenience function to the fscache netfs interface for cleaning up the page list at the end of asop readpages(). I know other filesystems (NFS) have ran into that since I've seen a few similar traces in Google search and the cachefs mailig list. The second patch new make Ceph use this interface.

I've been running this code (minus the BUG fix) on clients for a couple weeks with moderate 24/7 use without issues. At this point in time I feel like it's solid enough to go into the ceph kclient.

Please pull the code from my repository:
https://bitbucket.org/adfin/linux-fs.git branch: wip-ceph-fscache

The first two patches I included were not written by me but were written by Hongyi Jia. He implemented the cookie re-validation scheme into fscache core.

Finally, I CCed a couple other mailing lists (fsdevel, nfs) because the new fscache_readpages_cancel() should be used by other filesystems to avoid the same problem.

Hongyi Jia (2):
new cachefiles interface to check cache consistency new fscache interface to check cache consistency

Milosz Tanski (3):
ceph: use fscache as a local presisent cache
fscache: netfs function for cleanup post readpages
ceph: clean PgPrivate2 on returning from readpages

 fs/cachefiles/interface.c     |  19 +++
 fs/cachefiles/internal.h      |   1 +
 fs/cachefiles/xattr.c         |  39 ++++++
 fs/ceph/Kconfig               |   9 ++
 fs/ceph/Makefile              |   2 +
 fs/ceph/addr.c                |  39 +++++-
 fs/ceph/cache.c               | 311 ++++++++++++++++++++++++++++++++++++++++++
 fs/ceph/cache.h               | 130 ++++++++++++++++++
 fs/ceph/caps.c                |  19 ++-
 fs/ceph/file.c                |  17 +++
 fs/ceph/inode.c               |  66 ++++++++-
 fs/ceph/super.c               |  47 ++++++-
 fs/ceph/super.h               |  17 +++
 fs/fscache/cookie.c           |  22 +++
 fs/fscache/page.c             |  16 +++
 include/linux/fscache-cache.h |   4 +
 include/linux/fscache.h       |  39 ++++++
 17 files changed, 785 insertions(+), 12 deletions(-)
 create mode 100644 fs/ceph/cache.c
 create mode 100644 fs/ceph/cache.h

--
1.8.1.2

David, are the fscache patches here ready for the next merge window? Do you have a preference for whose tree they go through?

Quoted 2 lines · Sage Weil

David, are the fscache patches here ready for the next merge window? Do you have a preference for whose tree they go through?

There's only one problem - patch 1 needs to come _after_ patch 2 to avoid breaking git bisect. Plus these patches 2 and 4 extend the fscache API without adjusting the documentation - but that can be added later.

And I think Milosz deserves a beer (or other poison of his choice;-) for finding a longstanding irritating bug.

I think AFS, CIFS, NFS and 9P all need patching too, but I can attend to that.

Should I take the patches through my tree? Then I can make the adjustments.

Hi David!

Quoted 12 lines · David Howells

Quoted 2 lines · Sage Weil

David, are the fscache patches here ready for the next merge window? Do you have a preference for whose tree they go through?

There's only one problem - patch 1 needs to come _after_ patch 2 to avoid breaking git bisect. Plus these patches 2 and 4 extend the fscache API without adjusting the documentation - but that can be added later.

And I think Milosz deserves a beer (or other poison of his choice;-) for finding a longstanding irritating bug.

Quoted 3 lines

I think AFS, CIFS, NFS and 9P all need patching too, but I can attend to that.

Should I take the patches through my tree? Then I can make the adjustments.

Sure. Do you want the Ceph patches as well, or just the fscache bits? I'll repost the latest version, as it's gotten several fixes squashed in.