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From: David Howells <dhowells@redhat.com>
To: linux-cachefs@redhat.com
Cc: dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Jeff Layton <jlayton@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Omar Sandoval <osandov@osandov.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
	linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
	v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 37/64] cachefiles: Provide a function to check how much space there is
Date: Mon, 29 Nov 2021 14:31:33 +0000	[thread overview]
Message-ID: <163819629322.215744.13457425294680841213.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk>

Provide a function to check how much space there is.  This also flips the
state on the cache and will signal the daemon to inform it of the change
and to ask it to do some culling if necessary.

We will also need to subtract the amount of data currently being written to
the cache (cache->b_writing) from the amount of available space to avoid
hitting ENOSPC accidentally.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
---

 fs/cachefiles/Makefile   |    1 
 fs/cachefiles/cache.c    |  103 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/cachefiles/daemon.c   |    2 -
 fs/cachefiles/internal.h |    7 +++
 4 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100644 fs/cachefiles/cache.c

diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile
index f008524bb78f..463e3d608b75 100644
--- a/fs/cachefiles/Makefile
+++ b/fs/cachefiles/Makefile
@@ -4,6 +4,7 @@
 #
 
 cachefiles-y := \
+	cache.o \
 	daemon.o \
 	main.o \
 	security.o
diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c
new file mode 100644
index 000000000000..73636f89eefa
--- /dev/null
+++ b/fs/cachefiles/cache.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Manage high-level VFS aspects of a cache.
+ *
+ * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/slab.h>
+#include <linux/statfs.h>
+#include <linux/namei.h>
+#include "internal.h"
+
+/*
+ * See if we have space for a number of pages and/or a number of files in the
+ * cache
+ */
+int cachefiles_has_space(struct cachefiles_cache *cache,
+			 unsigned fnr, unsigned bnr)
+{
+	struct kstatfs stats;
+	u64 b_avail, b_writing;
+	int ret;
+
+	struct path path = {
+		.mnt	= cache->mnt,
+		.dentry	= cache->mnt->mnt_root,
+	};
+
+	//_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
+	//       (unsigned long long) cache->frun,
+	//       (unsigned long long) cache->fcull,
+	//       (unsigned long long) cache->fstop,
+	//       (unsigned long long) cache->brun,
+	//       (unsigned long long) cache->bcull,
+	//       (unsigned long long) cache->bstop,
+	//       fnr, bnr);
+
+	/* find out how many pages of blockdev are available */
+	memset(&stats, 0, sizeof(stats));
+
+	ret = vfs_statfs(&path, &stats);
+	if (ret < 0) {
+		trace_cachefiles_vfs_error(NULL, d_inode(path.dentry), ret,
+					   cachefiles_trace_statfs_error);
+		if (ret == -EIO)
+			cachefiles_io_error(cache, "statfs failed");
+		_leave(" = %d", ret);
+		return ret;
+	}
+
+	b_avail = stats.f_bavail >> cache->bshift;
+	b_writing = atomic_long_read(&cache->b_writing);
+	if (b_avail > b_writing)
+		b_avail -= b_writing;
+	else
+		b_avail = 0;
+
+	//_debug("avail %llu,%llu",
+	//       (unsigned long long)stats.f_ffree,
+	//       (unsigned long long)b_avail);
+
+	/* see if there is sufficient space */
+	if (stats.f_ffree > fnr)
+		stats.f_ffree -= fnr;
+	else
+		stats.f_ffree = 0;
+
+	if (b_avail > bnr)
+		b_avail -= bnr;
+	else
+		b_avail = 0;
+
+	ret = -ENOBUFS;
+	if (stats.f_ffree < cache->fstop ||
+	    b_avail < cache->bstop)
+		goto begin_cull;
+
+	ret = 0;
+	if (stats.f_ffree < cache->fcull ||
+	    b_avail < cache->bcull)
+		goto begin_cull;
+
+	if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
+	    stats.f_ffree >= cache->frun &&
+	    b_avail >= cache->brun &&
+	    test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
+	    ) {
+		_debug("cease culling");
+		cachefiles_state_changed(cache);
+	}
+
+	//_leave(" = 0");
+	return 0;
+
+begin_cull:
+	if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
+		_debug("### CULL CACHE ###");
+		cachefiles_state_changed(cache);
+	}
+
+	_leave(" = %d", ret);
+	return ret;
+}
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 4cfb7c8b37d0..7d4691614cec 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -167,7 +167,7 @@ static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
 		return 0;
 
 	/* check how much space the cache has */
-	// PLACEHOLDER: Check space
+	cachefiles_has_space(cache, 0, 0);
 
 	/* summarise */
 	f_released = atomic_xchg(&cache->f_released, 0);
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 7fd5429715ea..3783a3e01027 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -39,6 +39,7 @@ struct cachefiles_cache {
 	atomic_t			gravecounter;	/* graveyard uniquifier */
 	atomic_t			f_released;	/* number of objects released lately */
 	atomic_long_t			b_released;	/* number of blocks released lately */
+	atomic_long_t			b_writing;	/* Number of blocks being written */
 	unsigned			frun_percent;	/* when to stop culling (% files) */
 	unsigned			fcull_percent;	/* when to start culling (% files) */
 	unsigned			fstop_percent;	/* when to stop allocating (% files) */
@@ -74,6 +75,12 @@ static inline void cachefiles_state_changed(struct cachefiles_cache *cache)
 	wake_up_all(&cache->daemon_pollwq);
 }
 
+/*
+ * cache.c
+ */
+extern int cachefiles_has_space(struct cachefiles_cache *cache,
+				unsigned fnr, unsigned bnr);
+
 /*
  * daemon.c
  */



  parent reply	other threads:[~2021-11-29 14:33 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-29 14:22 [PATCH 00/64] fscache, cachefiles: Rewrite David Howells
2021-11-29 14:22 ` [PATCH 01/64] fscache, cachefiles: Disable configuration David Howells
2021-11-29 14:22 ` [PATCH 02/64] cachefiles: Delete the cachefiles driver pending rewrite David Howells
2021-11-29 14:23 ` [PATCH 03/64] fscache: Remove the contents of the fscache driver, " David Howells
2021-11-29 14:23 ` [PATCH 04/64] netfs: Display the netfs inode number in the netfs_read tracepoint David Howells
2021-11-29 14:23 ` [PATCH 05/64] netfs: Pass a flag to ->prepare_write() to say if there's no alloc'd space David Howells
2021-11-29 14:24 ` [PATCH 06/64] fscache: Introduce new driver David Howells
2021-11-29 14:24 ` [PATCH 07/64] fscache: Implement a hash function David Howells
2021-11-29 14:24 ` [PATCH 08/64] fscache: Implement cache registration David Howells
2021-11-29 14:24 ` [PATCH 09/64] fscache: Implement volume registration David Howells
2021-11-29 14:25 ` [PATCH 10/64] fscache: Implement cookie registration David Howells
2021-11-29 14:25 ` [PATCH 11/64] fscache: Implement cache-level access helpers David Howells
2021-11-29 14:25 ` [PATCH 12/64] fscache: Implement volume-level " David Howells
2021-11-29 14:25 ` [PATCH 13/64] fscache: Implement cookie-level " David Howells
2021-11-29 14:26 ` [PATCH 14/64] fscache: Implement functions add/remove a cache David Howells
2021-11-29 14:26 ` [PATCH 15/64] fscache: Provide and use cache methods to lookup/create/free a volume David Howells
2021-11-29 14:26 ` [PATCH 16/64] fscache: Add a function for a cache backend to note an I/O error David Howells
2021-11-29 14:26 ` [PATCH 17/64] fscache: Implement simple cookie state machine David Howells
2021-11-29 14:26 ` [PATCH 18/64] fscache: Implement cookie user counting and resource pinning David Howells
2021-11-29 14:27 ` [PATCH 19/64] fscache: Implement cookie invalidation David Howells
2021-11-29 14:27 ` [PATCH 20/64] fscache: Provide a means to begin an operation David Howells
2021-11-29 14:28 ` [PATCH 21/64] fscache: Count data storage objects in a cache David Howells
2021-11-29 14:28 ` [PATCH 22/64] fscache: Provide read/write stat counters for the cache David Howells
2021-11-29 14:28 ` [PATCH 23/64] fscache: Provide a function to let the netfs update its coherency data David Howells
2021-11-29 14:28 ` [PATCH 24/64] netfs: Pass more information on how to deal with a hole in the cache David Howells
2021-12-06 11:42   ` JeffleXu
2021-12-09 16:49   ` David Howells
2021-11-29 14:28 ` [PATCH 25/64] fscache: Implement raw I/O interface David Howells
2021-11-29 14:29 ` [PATCH 26/64] fscache: Implement higher-level write " David Howells
2021-11-29 14:29 ` [PATCH 27/64] vfs, fscache: Implement pinning of cache usage for writeback David Howells
2021-11-29 14:29 ` [PATCH 28/64] fscache: Provide a function to note the release of a page David Howells
2021-11-29 14:30 ` [PATCH 29/64] fscache: Provide a function to resize a cookie David Howells
2021-11-29 14:30 ` [PATCH 30/64] cachefiles: Introduce rewritten driver David Howells
2021-11-29 14:30 ` [PATCH 31/64] cachefiles: Define structs David Howells
2021-11-29 14:30 ` [PATCH 32/64] cachefiles: Add some error injection support David Howells
2021-11-29 14:30 ` [PATCH 33/64] cachefiles: Add a couple of tracepoints for logging errors David Howells
2021-11-29 14:31 ` [PATCH 34/64] cachefiles: Add cache error reporting macro David Howells
2021-11-29 14:31 ` [PATCH 35/64] cachefiles: Add security derivation David Howells
2021-11-29 14:31 ` [PATCH 36/64] cachefiles: Register a miscdev and parse commands over it David Howells
2021-11-29 14:31 ` David Howells [this message]
2021-11-29 14:31 ` [PATCH 38/64] vfs, cachefiles: Mark a backing file in use with an inode flag David Howells
2021-11-29 14:31 ` [PATCH 39/64] cachefiles: Implement a function to get/create a directory in the cache David Howells
2021-11-29 14:32 ` [PATCH 40/64] cachefiles: Implement cache registration and withdrawal David Howells
2021-11-29 14:32 ` [PATCH 41/64] cachefiles: Implement volume support David Howells
2021-11-29 14:33 ` [PATCH 42/64] cachefiles: Add tracepoints for calls to the VFS David Howells
2021-11-29 14:33 ` [PATCH 43/64] cachefiles: Implement object lifecycle funcs David Howells
2021-11-29 14:33 ` [PATCH 44/64] cachefiles: Implement key to filename encoding David Howells
2021-12-01  5:46   ` JeffleXu
2021-12-01  8:29   ` David Howells
2021-11-29 14:33 ` [PATCH 45/64] cachefiles: Implement metadata/coherency data storage in xattrs David Howells
2021-11-29 14:33 ` [PATCH 46/64] cachefiles: Mark a backing file in use with an inode flag David Howells
2021-11-29 14:33 ` [PATCH 47/64] cachefiles: Implement culling daemon commands David Howells
2021-11-29 14:34 ` [PATCH 48/64] cachefiles: Implement backing file wrangling David Howells
2021-11-29 14:34 ` [PATCH 49/64] cachefiles: Implement begin and end I/O operation David Howells
2021-11-29 14:34 ` [PATCH 50/64] cachefiles: Implement cookie resize for truncate David Howells
2021-11-29 14:34 ` [PATCH 51/64] cachefiles: Implement the I/O routines David Howells
2021-11-30 16:15   ` Nathan Chancellor
2021-11-30 21:05   ` David Howells
2021-11-29 14:34 ` [PATCH 52/64] cachefiles: Allow cachefiles to actually function David Howells
2021-11-29 14:35 ` [PATCH 53/64] fscache, cachefiles: Display stats of no-space events David Howells
2021-11-29 14:35 ` [PATCH 54/64] fscache, cachefiles: Display stat of culling events David Howells
2021-11-29 14:36 ` [PATCH 55/64] afs: Handle len being extending over page end in write_begin/write_end David Howells
2021-11-29 14:36 ` [PATCH 56/64] afs: Fix afs_write_end() to handle len > page size David Howells
2021-11-29 14:36 ` [PATCH 57/64] afs: Convert afs to use the new fscache API David Howells
2021-11-29 14:37 ` [PATCH 58/64] afs: Copy local writes to the cache when writing to the server David Howells
2021-11-29 14:37 ` [PATCH 59/64] afs: Skip truncation on the server of data we haven't written yet David Howells
2021-11-29 14:37 ` [PATCH 60/64] 9p: Use fscache indexing rewrite and reenable caching David Howells
2021-11-29 14:37 ` [PATCH 61/64] 9p: Copy local writes to the cache when writing to the server David Howells
2021-11-29 14:38 ` [PATCH 62/64] nfs: Convert to new fscache volume/cookie API David Howells
2021-11-29 14:38 ` [PATCH 63/64] cifs: Support fscache indexing rewrite (untested) David Howells
2021-11-29 14:38 ` [PATCH 64/64] fscache: Rewrite documentation David Howells
2021-11-29 18:12 ` [PATCH 00/64] fscache, cachefiles: Rewrite Linus Torvalds
2021-11-29 21:40 ` [PATCH 35/64] cachefiles: Add security derivation David Howells

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