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Date: Mon, 25 Jul 2016 23:47:24 -0400 (EDT)
From: George Amvrosiadis <gamvrosi@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...iv.linux.org.uk>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-mm@...ck.org
Cc: George Amvrosiadis <gamvrosi@...il.com>
Subject: [PATCH 3/3] mm/duet: framework code
The Duet framework code:
- bittree.c: red-black bitmap tree that keeps track of items of interest
- debug.c: functions used to print information used to debug Duet
- hash.c: implementation of the global hash table where page events are stored
for all tasks
- hook.c: the function invoked by the page cache hooks when Duet is online
- init.c: routines used to bring Duet online or offline
- path.c: routines performing resolution of UUIDs to paths using d_path
- task.c: implementation of Duet task fd operations
Signed-off-by: George Amvrosiadis <gamvrosi@...il.com>
---
init/Kconfig | 2 +
mm/Makefile | 1 +
mm/duet/Kconfig | 31 +++
mm/duet/Makefile | 7 +
mm/duet/bittree.c | 537 +++++++++++++++++++++++++++++++++++++++++++++++++
mm/duet/common.h | 211 ++++++++++++++++++++
mm/duet/debug.c | 98 +++++++++
mm/duet/hash.c | 315 +++++++++++++++++++++++++++++
mm/duet/hook.c | 81 ++++++++
mm/duet/init.c | 172 ++++++++++++++++
mm/duet/path.c | 184 +++++++++++++++++
mm/duet/syscall.h | 61 ++++++
mm/duet/task.c | 584 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
13 files changed, 2284 insertions(+)
create mode 100644 mm/duet/Kconfig
create mode 100644 mm/duet/Makefile
create mode 100644 mm/duet/bittree.c
create mode 100644 mm/duet/common.h
create mode 100644 mm/duet/debug.c
create mode 100644 mm/duet/hash.c
create mode 100644 mm/duet/hook.c
create mode 100644 mm/duet/init.c
create mode 100644 mm/duet/path.c
create mode 100644 mm/duet/syscall.h
create mode 100644 mm/duet/task.c
diff --git a/init/Kconfig b/init/Kconfig
index c02d897..6f94b5a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -294,6 +294,8 @@ config USELIB
earlier, you may need to enable this syscall. Current systems
running glibc can safely disable this.
+source mm/duet/Kconfig
+
config AUDIT
bool "Auditing support"
depends on NET
diff --git a/mm/Makefile b/mm/Makefile
index 78c6f7d..074c15f 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -99,3 +99,4 @@ obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o
obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o
+obj-$(CONFIG_DUET) += duet/
diff --git a/mm/duet/Kconfig b/mm/duet/Kconfig
new file mode 100644
index 0000000..2f3a0c5
--- /dev/null
+++ b/mm/duet/Kconfig
@@ -0,0 +1,31 @@
+config DUET
+ bool "Duet framework support"
+
+ help
+ Duet is a framework aiming to reduce the IO footprint of analytics
+ and maintenance work. By exposing page cache events to these tasks,
+ it allows them to adapt their data processing order, in order to
+ benefit from data available in the page cache. Duet's operation is
+ based on hooks into the page cache.
+
+ To compile support for Duet, say Y.
+
+config DUET_STATS
+ bool "Duet statistics collection"
+ depends on DUET
+ help
+ This option enables support for the collection of statistics on the
+ operation of Duet. It will print information about the data structures
+ used internally, and profiling information about the framework.
+
+ If unsure, say N.
+
+config DUET_DEBUG
+ bool "Duet debugging support"
+ depends on DUET
+ help
+ Enable runtime debugging support for the Duet framework. This may
+ enable additional and expensive checks with negative impact on
+ performance.
+
+ To compile debugging support for Duet, say Y. If unsure, say N.
diff --git a/mm/duet/Makefile b/mm/duet/Makefile
new file mode 100644
index 0000000..c0c9e11
--- /dev/null
+++ b/mm/duet/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for the linux Duet framework.
+#
+
+obj-$(CONFIG_DUET) += duet.o
+
+duet-y := init.o hash.o hook.o task.o bittree.o path.o debug.o
diff --git a/mm/duet/bittree.c b/mm/duet/bittree.c
new file mode 100644
index 0000000..3b20c35
--- /dev/null
+++ b/mm/duet/bittree.c
@@ -0,0 +1,537 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include "common.h"
+
+#define BMAP_READ 0x01 /* Read bmaps (overrides other flags) */
+#define BMAP_CHECK 0x02 /* Check given bmap value expression */
+ /* Sets bmaps to match expression if not set */
+
+/* Bmap expressions can be formed using the following flags: */
+#define BMAP_DONE_SET 0x04 /* Set done bmap values */
+#define BMAP_DONE_RST 0x08 /* Reset done bmap values */
+#define BMAP_RELV_SET 0x10 /* Set relevant bmap values */
+#define BMAP_RELV_RST 0x20 /* Reset relevant bmap values */
+#define BMAP_SEEN_SET 0x40 /* Set seen bmap values */
+#define BMAP_SEEN_RST 0x80 /* Reset seen bmap values */
+
+/* Some macros to make our life easier */
+#define BMAP_ALL_SET (BMAP_SEEN_SET | BMAP_RELV_SET | BMAP_DONE_SET)
+#define BMAP_ALL_RST (BMAP_SEEN_RST | BMAP_RELV_RST | BMAP_DONE_RST)
+
+#define BITTREE_RANGE PAGE_SIZE /* Bytes per bitmap bit */
+#define BITS_PER_NODE (32768 * 8) /* 32KB bitmaps */
+
+#define UUID_IDX(uuid) (((unsigned long long) uuid.gen << 32) | \
+ (unsigned long long) uuid.ino)
+/*
+ * The following functions are wrappers for the basic bitmap functions.
+ * A bitmap is characterized by a starting offset (bstart). The wrappers
+ * translate an arbitrary idx to the appropriate bit.
+ */
+
+/* Sets (or resets) a single bit */
+static int bmap_set(unsigned long *bmap, __u64 start, __u64 idx, __u8 do_set)
+{
+ __u64 bofft = idx - start;
+
+ if (bofft + 1 >= start + (BITS_PER_NODE * BITTREE_RANGE))
+ return -1;
+
+ /* Convert range to bitmap granularity */
+ do_div(bofft, BITTREE_RANGE);
+
+ if (do_set)
+ bitmap_set(bmap, (unsigned int)bofft, 1);
+ else
+ bitmap_clear(bmap, (unsigned int)bofft, 1);
+
+ return 0;
+}
+
+/* Returns value of bit at idx */
+static int bmap_read(unsigned long *bmap, __u64 start, __u64 idx)
+{
+ __u64 bofft64 = idx - start;
+ unsigned long *p, mask;
+ unsigned int bofft;
+
+ if (bofft64 + 1 >= start + (BITS_PER_NODE * BITTREE_RANGE))
+ return -1;
+
+ /* Convert offset to bitmap granularity */
+ do_div(bofft64, BITTREE_RANGE);
+ bofft = (unsigned int)bofft64;
+
+ /* Check the bits */
+ p = bmap + BIT_WORD(bofft);
+ mask = BITMAP_FIRST_WORD_MASK(bofft) & BITMAP_LAST_WORD_MASK(bofft + 1);
+
+ if ((*p) & mask)
+ return 1;
+
+ return 0;
+}
+
+/* Checks whether a bit is set */
+static int bmap_chk(unsigned long *bmap, __u64 start, __u64 idx, __u8 do_set)
+{
+ __u64 bofft64 = idx - start;
+ unsigned long *p, mask;
+ unsigned int bofft;
+
+ if (bofft64 + 1 >= start + (BITS_PER_NODE * BITTREE_RANGE))
+ return -1;
+
+ /* Convert range to bitmap granularity */
+ do_div(bofft64, BITTREE_RANGE);
+
+ /* Now it is safe to cast these variables */
+ bofft = (unsigned int)bofft64;
+
+ /* Check the bit */
+ p = bmap + BIT_WORD(bofft);
+ mask = BITMAP_FIRST_WORD_MASK(bofft) & BITMAP_LAST_WORD_MASK(bofft + 1);
+
+ if (do_set && !((*p) & mask))
+ return 0;
+ else if (!do_set && !(~(*p) & mask))
+ return 0;
+
+ return 1;
+}
+
+/* Initializes a bitmap tree node */
+static struct bmap_rbnode *bnode_init(struct duet_bittree *bt, __u64 idx)
+{
+ struct bmap_rbnode *bnode = NULL;
+
+#ifdef CONFIG_DUET_STATS
+ if (bt) {
+ (bt->statcur)++;
+ if (bt->statcur > bt->statmax) {
+ bt->statmax = bt->statcur;
+ pr_info("duet: %llu BitTree nodes (%llub)\n",
+ bt->statmax, bt->statmax * BITS_PER_NODE / 8);
+ }
+ }
+#endif /* CONFIG_DUET_STATS */
+
+ bnode = kmalloc(sizeof(*bnode), GFP_NOWAIT);
+ if (!bnode)
+ return NULL;
+
+ bnode->done = kzalloc(sizeof(unsigned long) *
+ BITS_TO_LONGS(BITS_PER_NODE), GFP_NOWAIT);
+ if (!bnode->done) {
+ kfree(bnode);
+ return NULL;
+ }
+
+ /* Allocate relevant bitmap, if needed */
+ bnode->relv = kzalloc(sizeof(unsigned long) *
+ BITS_TO_LONGS(BITS_PER_NODE), GFP_NOWAIT);
+ if (!bnode->relv) {
+ kfree(bnode->done);
+ kfree(bnode);
+ return NULL;
+ }
+
+ bnode->seen = kzalloc(sizeof(unsigned long) *
+ BITS_TO_LONGS(BITS_PER_NODE), GFP_NOWAIT);
+ if (!bnode->seen) {
+ kfree(bnode->relv);
+ kfree(bnode->done);
+ kfree(bnode);
+ return NULL;
+ }
+
+ RB_CLEAR_NODE(&bnode->node);
+ bnode->idx = idx;
+ return bnode;
+}
+
+static void bnode_dispose(struct bmap_rbnode *bnode, struct rb_node *rbnode,
+ struct duet_bittree *bt)
+{
+#ifdef CONFIG_DUET_STATS
+ if (bt)
+ (bt->statcur)--;
+#endif /* CONFIG_DUET_STATS */
+ rb_erase(rbnode, &bt->root);
+ kfree(bnode->relv);
+ kfree(bnode->seen);
+ kfree(bnode->done);
+ kfree(bnode);
+}
+
+/*
+ * Traverses bitmap nodes to read/set/unset/check a specific bit across bitmaps.
+ * May insert/remove bitmap nodes as needed.
+ *
+ * If DUET_BMAP_READ is set:
+ * - the bitmap value for idx are read for one or all bitmaps
+ * Otherwise, if DUET_BMAP_CHECK flag is set:
+ * - return value 1 means the idx matches the given flags
+ * - return value 0 means the idx doesn't match the given flags
+ * Otherwise, if neither flag is set:
+ * - return value 0 means the idx was updated to match given flags
+ *
+ * In all cases, a return value -1 denotes an error.
+ */
+static int __update_tree(struct duet_bittree *bt, __u64 idx, __u8 flags)
+{
+ int found, ret, res;
+ __u64 node_offt, div_rem;
+ struct rb_node **link, *parent;
+ struct bmap_rbnode *bnode = NULL;
+ unsigned long iflags;
+
+ local_irq_save(iflags);
+ spin_lock(&bt->lock);
+
+ div64_u64_rem(idx, BITTREE_RANGE * BITS_PER_NODE, &div_rem);
+ node_offt = idx - div_rem;
+
+ /* Look up BitTree node */
+ found = 0;
+ link = &(bt->root).rb_node;
+ parent = NULL;
+
+ while (*link) {
+ parent = *link;
+ bnode = rb_entry(parent, struct bmap_rbnode, node);
+
+ if (bnode->idx > node_offt) {
+ link = &(*link)->rb_left;
+ } else if (bnode->idx < node_offt) {
+ link = &(*link)->rb_right;
+ } else {
+ found = 1;
+ break;
+ }
+ }
+
+ /* If we're just reading bitmap values, return them now */
+ if (flags & BMAP_READ) {
+ ret = 0;
+
+ if (!found)
+ goto done;
+
+ /* First read seen bit */
+ res = bmap_read(bnode->seen, bnode->idx, idx);
+ if (res == -1) {
+ ret = -1;
+ goto done;
+ }
+ ret |= res << 2;
+
+ /* Then read relevant bit */
+ res = bmap_read(bnode->relv, bnode->idx, idx);
+ if (res == -1) {
+ ret = -1;
+ goto done;
+ }
+ ret |= res << 1;
+
+ /* Read done bit */
+ res = bmap_read(bnode->done, bnode->idx, idx);
+ if (res == -1) {
+ ret = -1;
+ goto done;
+ }
+
+ ret |= res;
+ goto done;
+ }
+
+ /*
+ * Take appropriate action based on whether we found the node
+ * and whether we plan to update (SET/RST), or only CHECK it.
+ *
+ * NULL | Found !Found |
+ * -------+------------------------------------+
+ * SET | Set Bits | Init new node |
+ * |------------------+-----------------|
+ * RST | Clear (dispose?) | Nothing |
+ * -------+------------------------------------+
+ *
+ * CHECK | Found !Found |
+ * -------+------------------------------------+
+ * SET | Check Bits | Return false |
+ * |------------------+-----------------|
+ * RST | Check Bits | Continue |
+ * -------+------------------------------------+
+ */
+
+ /* First handle setting (or checking set) bits */
+ if (flags & BMAP_ALL_SET) {
+ if (!found && !(flags & BMAP_CHECK)) {
+ /* Insert the new node */
+ bnode = bnode_init(bt, node_offt);
+ if (!bnode) {
+ ret = -1;
+ goto done;
+ }
+
+ rb_link_node(&bnode->node, parent, link);
+ rb_insert_color(&bnode->node, &bt->root);
+
+ } else if (!found && (flags & BMAP_CHECK)) {
+ /* Looking for set bits, node didn't exist */
+ ret = 0;
+ goto done;
+ }
+
+ /* Set the bits. Return -1 if something goes wrong. */
+ if (!(flags & BMAP_CHECK)) {
+ if ((flags & BMAP_SEEN_SET) &&
+ bmap_set(bnode->seen, bnode->idx, idx, 1)) {
+ ret = -1;
+ goto done;
+ }
+
+ if ((flags & BMAP_RELV_SET) &&
+ bmap_set(bnode->relv, bnode->idx, idx, 1)) {
+ ret = -1;
+ goto done;
+ }
+
+ if ((flags & BMAP_DONE_SET) &&
+ bmap_set(bnode->done, bnode->idx, idx, 1)) {
+ ret = -1;
+ goto done;
+ }
+
+ /* Check the bits. Return if any bits are off */
+ } else {
+ if (flags & BMAP_SEEN_SET) {
+ ret = bmap_chk(bnode->seen, bnode->idx, idx, 1);
+ if (ret != 1)
+ goto done;
+ }
+
+ if (flags & BMAP_RELV_SET) {
+ ret = bmap_chk(bnode->relv, bnode->idx, idx, 1);
+ if (ret != 1)
+ goto done;
+ }
+
+ ret = bmap_chk(bnode->done, bnode->idx, idx, 1);
+ if (ret != 1)
+ goto done;
+ }
+ }
+
+ /* Now handle unsetting any bits */
+ if (found && (flags & BMAP_ALL_RST)) {
+ /* Clear the bits. Return -1 if something goes wrong. */
+ if (!(flags & BMAP_CHECK)) {
+ if ((flags & BMAP_SEEN_RST) &&
+ bmap_set(bnode->seen, bnode->idx, idx, 0)) {
+ ret = -1;
+ goto done;
+ }
+
+ if ((flags & BMAP_RELV_RST) &&
+ bmap_set(bnode->relv, bnode->idx, idx, 0)) {
+ ret = -1;
+ goto done;
+ }
+
+ if ((flags & BMAP_DONE_RST) &&
+ bmap_set(bnode->done, bnode->idx, idx, 0)) {
+ ret = -1;
+ goto done;
+ }
+
+ /* Check the bits. Return if any bits are off */
+ } else {
+ if (flags & BMAP_SEEN_RST) {
+ ret = bmap_chk(bnode->seen, bnode->idx, idx, 0);
+ if (ret != 1)
+ goto done;
+ }
+
+ if (flags & BMAP_RELV_RST) {
+ ret = bmap_chk(bnode->relv, bnode->idx, idx, 0);
+ if (ret != 1)
+ goto done;
+ }
+
+ ret = bmap_chk(bnode->done, bnode->idx, idx, 0);
+ if (ret != 1)
+ goto done;
+ }
+
+ /* Dispose of the node if empty */
+ if (!(flags & BMAP_CHECK) &&
+ bitmap_empty(bnode->done, BITS_PER_NODE) &&
+ bitmap_empty(bnode->seen, BITS_PER_NODE) &&
+ bitmap_empty(bnode->relv, BITS_PER_NODE))
+ bnode_dispose(bnode, parent, bt);
+ }
+
+ if (!(flags & BMAP_CHECK))
+ ret = 0;
+ else
+ ret = 1;
+
+done:
+ if (ret == -1)
+ pr_err("duet: blocks were not %s\n",
+ (flags & BMAP_READ) ? "read" :
+ ((flags & BMAP_CHECK) ? "checked" : "modified"));
+ spin_unlock(&bt->lock);
+ local_irq_restore(iflags);
+ return ret;
+}
+
+/*
+ * Check if we have seen this inode before. If not, check if it is relevant.
+ * Then, check whether it's done.
+ */
+static int do_bittree_check(struct duet_bittree *bt, struct duet_uuid uuid,
+ struct duet_task *task, struct inode *inode)
+{
+ int ret, bits;
+ unsigned long long idx = UUID_IDX(uuid);
+
+ bits = __update_tree(bt, idx, BMAP_READ);
+
+ if (!(bits & 0x4)) {
+ /* We have not seen this inode before */
+ if (inode) {
+ ret = do_find_path(task, inode, 0, NULL, 0);
+ } else if (task) {
+ ret = duet_find_path(task, uuid, 0, NULL, 0);
+ } else {
+ pr_err("duet: check failed, no task/inode\n");
+ return -1;
+ }
+
+ if (!ret) {
+ /* Mark as relevant and return not done */
+ ret = __update_tree(bt, idx,
+ BMAP_SEEN_SET | BMAP_RELV_SET);
+ if (ret != -1)
+ ret = 0;
+
+ } else if (ret == -ENOENT) {
+ /* Mark as irrelevant and return done */
+ ret = __update_tree(bt, idx, BMAP_SEEN_SET);
+ if (ret != -1)
+ ret = 1;
+
+ } else {
+ pr_err("duet: inode relevance undetermined\n");
+ return -1;
+ }
+
+ } else {
+ /* We know this inode, return 1 if done, or irrelevant */
+ ret = ((bits & 0x1) || !(bits & 0x2)) ? 1 : 0;
+ }
+
+ return ret;
+}
+
+/* Checks if a given inode is done. Skips inode lookup. */
+int bittree_check_inode(struct duet_bittree *bt, struct duet_task *task,
+ struct inode *inode)
+{
+ struct duet_uuid uuid;
+
+ uuid.ino = inode->i_ino;
+ uuid.gen = inode->i_generation;
+
+ return do_bittree_check(bt, uuid, task, inode);
+}
+
+/* Checks if the given entries are done */
+int bittree_check(struct duet_bittree *bt, struct duet_uuid uuid,
+ struct duet_task *task)
+{
+ return do_bittree_check(bt, uuid, task, NULL);
+}
+
+/* Mark done bit for given entries */
+int bittree_set(struct duet_bittree *bt, struct duet_uuid uuid)
+{
+ return __update_tree(bt, UUID_IDX(uuid), BMAP_DONE_SET);
+}
+
+/* Unmark done bit for given entries */
+int bittree_reset(struct duet_bittree *bt, struct duet_uuid uuid)
+{
+ return __update_tree(bt, UUID_IDX(uuid), BMAP_DONE_RST);
+}
+
+int bittree_print(struct duet_task *task)
+{
+ struct bmap_rbnode *bnode = NULL;
+ struct rb_node *node;
+ unsigned long iflags;
+
+ local_irq_save(iflags);
+ spin_lock(&task->bittree.lock);
+ pr_info("duet: Printing task bittree\n");
+ node = rb_first(&task->bittree.root);
+ while (node) {
+ bnode = rb_entry(node, struct bmap_rbnode, node);
+
+ /* Print node information */
+ pr_info("duet: Node key = %llu\n", bnode->idx);
+ pr_info("duet: Done bits set: %d out of %d\n",
+ bitmap_weight(bnode->done, BITS_PER_NODE),
+ BITS_PER_NODE);
+ pr_info("duet: Relv bits set: %d out of %d\n",
+ bitmap_weight(bnode->relv, BITS_PER_NODE),
+ BITS_PER_NODE);
+ pr_info("duet: Seen bits set: %d out of %d\n",
+ bitmap_weight(bnode->seen, BITS_PER_NODE),
+ BITS_PER_NODE);
+
+ node = rb_next(node);
+ }
+ spin_unlock(&task->bittree.lock);
+ local_irq_restore(iflags);
+
+ pr_info("duet: Task #%d bitmap has %d out of %lu bits set\n",
+ task->id, bitmap_weight(task->bucket_bmap,
+ duet_env.itm_hash_size), duet_env.itm_hash_size);
+
+ return 0;
+}
+
+void bittree_init(struct duet_bittree *bittree)
+{
+ spin_lock_init(&bittree->lock);
+ bittree->root = RB_ROOT;
+#ifdef CONFIG_DUET_STATS
+ bittree->statcur = bittree->statmax = 0;
+#endif /* CONFIG_DUET_STATS */
+}
+
+void bittree_destroy(struct duet_bittree *bittree)
+{
+ struct rb_node *rbnode;
+ struct bmap_rbnode *bnode;
+
+ while (!RB_EMPTY_ROOT(&bittree->root)) {
+ rbnode = rb_first(&bittree->root);
+ bnode = rb_entry(rbnode, struct bmap_rbnode, node);
+ bnode_dispose(bnode, rbnode, bittree);
+ }
+}
diff --git a/mm/duet/common.h b/mm/duet/common.h
new file mode 100644
index 0000000..1dac66b
--- /dev/null
+++ b/mm/duet/common.h
@@ -0,0 +1,211 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+#ifndef _COMMON_H
+#define _COMMON_H
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/bitmap.h>
+#include <linux/rculist.h>
+#include <linux/syscalls.h>
+#include <linux/duet.h>
+
+#ifdef DUET_DEBUG
+#define duet_dbg(...) pr_info(__VA_ARGS__)
+#else
+#define duet_dbg(...)
+#endif
+
+/*
+ * Duet can be state-based, and/or event-based.
+ *
+ * Event-based Duet monitors events that occurred on a page, during its
+ * time in the page cache: ADDED, REMOVED, DIRTY, and FLUSHED.
+ *
+ * State-based Duet monitors changes in the page cache since the last time
+ * a notification was sent to the interested application. Registering for
+ * EXIST informs the application of page additions or removals from the cache
+ * (i.e. ADDED and REMOVED events cancel each other out if the application
+ * hasn't been told in the meantime). Registering for MODIFIED events is a
+ * similar model, where unreported DIRTY and FLUSHED events cancel each other.
+ */
+#define DUET_PAGE_ADDED 0x0001
+#define DUET_PAGE_REMOVED 0x0002
+#define DUET_PAGE_DIRTY 0x0004
+#define DUET_PAGE_FLUSHED 0x0008
+#define DUET_PAGE_MODIFIED 0x0010
+#define DUET_PAGE_EXISTS 0x0020
+#define DUET_FD_NONBLOCK 0x0040
+
+/* Used only for page state */
+#define DUET_MASK_VALID 0x8000
+
+/* Some useful flags for clearing bitmaps */
+#define BMAP_SEEN 0x1
+#define BMAP_RELV 0x2
+#define BMAP_DONE 0x4
+
+#define DUET_DEF_NUMTASKS 8
+#define DUET_INODE_FREEING (I_WILL_FREE | I_FREEING | I_CLEAR)
+
+enum {
+ DUET_STATUS_OFF = 0,
+ DUET_STATUS_ON,
+ DUET_STATUS_INIT,
+ DUET_STATUS_CLEAN,
+};
+
+/*
+ * Item struct returned for processing.
+ * The UUID currently consists of the inode number, the inode generation
+ * (to help us identify cases of inode reuse), and the task id.
+ * For state-based duet, we mark a page if it EXISTS or is MODIFIED.
+ * For event-based duet, we mark a page added, removed, dirtied, and/or flushed.
+ * Acceptable event combinations will differ based on the task's subscription.
+ */
+struct duet_uuid {
+ unsigned long ino;
+ __u32 gen;
+ __u8 tid;
+};
+
+struct duet_item {
+ struct duet_uuid uuid;
+ unsigned long idx;
+ __u16 state;
+};
+
+/*
+ * Red-black bitmap tree node.
+ * Represents the range starting from idx. For block tasks, only the done
+ * bitmap is used. For file tasks, the seen and relv (relevant) bitmaps are
+ * also used. The semantics of different states are listed below, where an
+ * item can be in the unknown state due to a bitmap reset, or because it hasn't
+ * been encountered yet.
+ * - !SEEN && !RELV && !DONE: Item in unknown state
+ * - !SEEN && !RELV && DONE: Item processed, but in unknown state
+ * - SEEN && !RELV && !DONE: Item not relevant to the task
+ * - SEEN && RELV && !DONE: Item is relevant, but not processed
+ * - SEEN && RELV && DONE: Item is relevant, and has already been processed
+ */
+struct bmap_rbnode {
+ __u64 idx;
+ struct rb_node node;
+ unsigned long *seen;
+ unsigned long *relv;
+ unsigned long *done;
+};
+
+struct item_hnode {
+ struct hlist_bl_node node;
+ struct duet_item item;
+ __u8 refcount;
+ __u16 *state; /* One entry per task */
+};
+
+struct duet_bittree {
+ spinlock_t lock;
+ struct rb_root root;
+#ifdef CONFIG_DUET_STATS
+ __u64 statcur; /* Cur # of BitTree nodes */
+ __u64 statmax; /* Max # of BitTree nodes */
+#endif /* CONFIG_DUET_STATS */
+};
+
+struct duet_task {
+ __u8 id; /* Internal task ID */
+
+ int fd;
+ struct filename *name;
+ __u32 evtmask; /* Mask of subscribed events */
+ struct path *regpath; /* Registered path */
+ char *regpathname; /* Registered path name */
+ __u16 regpathlen; /* Length of path name */
+
+ /* Data structures linking task to framework */
+ struct list_head task_list;
+ wait_queue_head_t cleaner_queue;
+ atomic_t refcount;
+ char *pathbuf; /* Buffer for getpath */
+ struct duet_bittree bittree; /* Progress bitmap */
+ wait_queue_head_t event_queue; /* for read() and poll() */
+
+ /* Hash table bucket bitmap */
+ spinlock_t bbmap_lock;
+ unsigned long *bucket_bmap;
+ unsigned long bmap_cursor;
+};
+
+struct duet_info {
+ atomic_t status;
+ __u8 numtasks; /* Number of concurrent tasks */
+
+ /*
+ * Access to the task list is synchronized via a mutex. However, any
+ * operations that are on-going for a task (e.g. fetch) will increase
+ * its refcount. This refcount is consulted when disposing of the task.
+ */
+ struct mutex task_list_mutex;
+ struct list_head tasks;
+
+ /* ItemTable -- Global page state hash table */
+ struct hlist_bl_head *itm_hash_table;
+ unsigned long itm_hash_size;
+ unsigned long itm_hash_shift;
+ unsigned long itm_hash_mask;
+};
+
+extern struct duet_info duet_env;
+
+/* hook.c */
+void duet_hook(__u16 evtcode, void *data);
+
+/* hash.c */
+int hash_init(void);
+int hash_add(struct duet_task *task, struct duet_uuid uuid,
+ unsigned long idx, __u16 evtmask, short in_scan);
+int hash_fetch(struct duet_task *task, struct duet_item *itm);
+void hash_print(struct duet_task *task);
+
+/* task.c -- not in linux/duet.h */
+struct duet_task *duet_find_task(__u8 id);
+void duet_task_dispose(struct duet_task *task);
+
+/* path.c */
+int do_find_path(struct duet_task *task, struct inode *inode,
+ int getpath, char *buf, int bufsize);
+int duet_find_path(struct duet_task *task, struct duet_uuid uuid,
+ int getpath, char *buf, int bufsize);
+
+/* bittree.c */
+int bittree_check_inode(struct duet_bittree *bt, struct duet_task *task,
+ struct inode *inode);
+int bittree_check(struct duet_bittree *bt, struct duet_uuid uuid,
+ struct duet_task *task);
+int bittree_set(struct duet_bittree *bt, struct duet_uuid uuid);
+int bittree_reset(struct duet_bittree *bt, struct duet_uuid uuid);
+int bittree_print(struct duet_task *task);
+void bittree_init(struct duet_bittree *bittree);
+void bittree_destroy(struct duet_bittree *bittree);
+
+/* init.c */
+int duet_online(void);
+
+/* debug.c */
+int duet_print_bmap(__u8 id);
+int duet_print_item(__u8 id);
+int duet_print_list(struct duet_status_args __user *arg);
+
+#endif /* _COMMON_H */
diff --git a/mm/duet/debug.c b/mm/duet/debug.c
new file mode 100644
index 0000000..77a47b6
--- /dev/null
+++ b/mm/duet/debug.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include "common.h"
+#include "syscall.h"
+
+/* Do a preorder print of the BitTree */
+int duet_print_bmap(__u8 id)
+{
+ struct duet_task *task;
+
+ task = duet_find_task(id);
+ if (!task)
+ return -ENOENT;
+
+ if (bittree_print(task)) {
+ pr_err("duet: failed to print BitTree for task #%d\n",
+ task->id);
+ return -1;
+ }
+
+ /* decref and wake up cleaner if needed */
+ if (atomic_dec_and_test(&task->refcount))
+ wake_up(&task->cleaner_queue);
+
+ return 0;
+}
+
+/* Do a preorder print of the global hash table */
+int duet_print_item(__u8 id)
+{
+ struct duet_task *task;
+
+ task = duet_find_task(id);
+ if (!task)
+ return -ENOENT;
+
+ hash_print(task);
+
+ /* decref and wake up cleaner if needed */
+ if (atomic_dec_and_test(&task->refcount))
+ wake_up(&task->cleaner_queue);
+
+ return 0;
+}
+
+int duet_print_list(struct duet_status_args __user *arg)
+{
+ int i = 0;
+ struct duet_task *cur;
+ struct duet_status_args argh, *argp;
+
+ /* Copy in task list header (again) */
+ if (copy_from_user(&argh, arg, sizeof(argh)))
+ return -EFAULT;
+
+ /* Copy in entire task list */
+ argp = memdup_user(arg, sizeof(*argp) + (argh.numtasks *
+ sizeof(struct duet_task_attrs)));
+ if (IS_ERR(argp))
+ return PTR_ERR(argp);
+
+ /* Copy the info for the first numtasks */
+ mutex_lock(&duet_env.task_list_mutex);
+ list_for_each_entry(cur, &duet_env.tasks, task_list) {
+ argp->tasks[i].id = cur->id;
+ argp->tasks[i].fd = cur->fd;
+ memcpy(argp->tasks[i].name, cur->name->name, NAME_MAX);
+ argp->tasks[i].regmask = cur->evtmask;
+ memcpy(argp->tasks[i].path, cur->regpathname, cur->regpathlen);
+ i++;
+ if (i == argp->numtasks)
+ break;
+ }
+ mutex_unlock(&duet_env.task_list_mutex);
+
+ /* Copy out entire task list */
+ if (copy_to_user(arg, argp, sizeof(*argp) + (argp->numtasks *
+ sizeof(struct duet_task_attrs)))) {
+ pr_err("duet_print_list: failed to copy out list\n");
+ kfree(argp);
+ return -EINVAL;
+ }
+
+ duet_dbg("duet_print_list: success sending task list\n");
+ kfree(argp);
+ return 0;
+}
diff --git a/mm/duet/hash.c b/mm/duet/hash.c
new file mode 100644
index 0000000..c2644d6
--- /dev/null
+++ b/mm/duet/hash.c
@@ -0,0 +1,315 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include <linux/hash.h>
+#include "common.h"
+
+#define DUET_NEGATE_EXISTS (DUET_PAGE_ADDED | DUET_PAGE_REMOVED)
+#define DUET_NEGATE_MODIFIED (DUET_PAGE_DIRTY | DUET_PAGE_FLUSHED)
+
+/*
+ * Page state is retained in a global hash table shared by all tasks.
+ * Indexing is based on the page's inode number and offset.
+ */
+
+static unsigned long hash(unsigned long ino, unsigned long idx)
+{
+ unsigned long h;
+
+ h = (idx * ino ^ (GOLDEN_RATIO_PRIME + idx)) / L1_CACHE_BYTES;
+ h = h ^ ((h ^ GOLDEN_RATIO_PRIME) >> duet_env.itm_hash_shift);
+ return h & duet_env.itm_hash_mask;
+}
+
+int hash_init(void)
+{
+ /* Allocate power-of-2 number of buckets */
+ duet_env.itm_hash_shift = ilog2(totalram_pages);
+ duet_env.itm_hash_size = 1 << duet_env.itm_hash_shift;
+ duet_env.itm_hash_mask = duet_env.itm_hash_size - 1;
+
+ pr_debug("duet: allocated global hash table (%lu buckets)\n",
+ duet_env.itm_hash_size);
+ duet_env.itm_hash_table = vmalloc(sizeof(struct hlist_bl_head) *
+ duet_env.itm_hash_size);
+ if (!duet_env.itm_hash_table)
+ return 1;
+
+ memset(duet_env.itm_hash_table, 0, sizeof(struct hlist_bl_head) *
+ duet_env.itm_hash_size);
+ return 0;
+}
+
+/* Deallocate a hash table node */
+static void hnode_destroy(struct item_hnode *itnode)
+{
+ kfree(itnode->state);
+ kfree(itnode);
+}
+
+/* Allocate and initialize a new hash table node */
+static struct item_hnode *hnode_init(struct duet_uuid uuid, unsigned long idx)
+{
+ struct item_hnode *itnode = NULL;
+
+ itnode = kzalloc(sizeof(struct item_hnode), GFP_NOWAIT);
+ if (!itnode)
+ return NULL;
+
+ itnode->state = kcalloc(duet_env.numtasks, sizeof(*(itnode->state)),
+ GFP_NOWAIT);
+ if (!(itnode->state)) {
+ pr_err("duet: failed to allocate hash node state\n");
+ kfree(itnode);
+ return NULL;
+ }
+
+ (itnode->item).uuid = uuid;
+ (itnode->item).idx = idx;
+ itnode->refcount++;
+
+ return itnode;
+}
+
+/* Add one event into the hash table */
+int hash_add(struct duet_task *task, struct duet_uuid uuid, unsigned long idx,
+ __u16 evtmask, short in_scan)
+{
+ __u16 curmask = 0;
+ short found = 0;
+ unsigned long bnum, flags;
+ struct hlist_bl_head *b;
+ struct hlist_bl_node *n;
+ struct item_hnode *itnode;
+
+ evtmask &= task->evtmask;
+
+ /* Get the bucket */
+ bnum = hash(uuid.ino, idx);
+ b = duet_env.itm_hash_table + bnum;
+ local_irq_save(flags);
+ hlist_bl_lock(b);
+
+ /* Lookup the item in the bucket */
+ hlist_bl_for_each_entry(itnode, n, b, node) {
+ if ((itnode->item).uuid.ino == uuid.ino &&
+ (itnode->item).uuid.gen == uuid.gen &&
+ (itnode->item).idx == idx) {
+ found = 1;
+ break;
+ }
+ }
+
+ duet_dbg("duet: %s hash node (tid %d, ino%lu, gen%lu, idx%lu)\n",
+ found ? (in_scan ? "replacing" : "updating") : "inserting",
+ uuid.tid, uuid.ino, uuid.gen, idx);
+
+ if (found) {
+ curmask = itnode->state[task->id];
+
+ /* Only up the refcount if we are adding a new mask */
+ if (!(curmask & DUET_MASK_VALID) || in_scan) {
+ if (!in_scan)
+ itnode->refcount++;
+ curmask = evtmask | DUET_MASK_VALID;
+ goto check_dispose;
+ }
+
+ curmask |= evtmask | DUET_MASK_VALID;
+
+ /* Negate previous events and remove if needed */
+ if ((task->evtmask & DUET_PAGE_EXISTS) &&
+ ((curmask & DUET_NEGATE_EXISTS) == DUET_NEGATE_EXISTS))
+ curmask &= ~DUET_NEGATE_EXISTS;
+
+ if ((task->evtmask & DUET_PAGE_MODIFIED) &&
+ ((curmask & DUET_NEGATE_MODIFIED) == DUET_NEGATE_MODIFIED))
+ curmask &= ~DUET_NEGATE_MODIFIED;
+
+check_dispose:
+ if ((curmask == DUET_MASK_VALID) && (itnode->refcount == 1)) {
+ if (itnode->refcount != 1) {
+ itnode->state[task->id] = 0;
+ } else {
+ hlist_bl_del(&itnode->node);
+ hnode_destroy(itnode);
+ }
+
+ /* Are we still interested in this bucket? */
+ hlist_bl_for_each_entry(itnode, n, b, node) {
+ if (itnode->state[task->id] & DUET_MASK_VALID) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found)
+ clear_bit(bnum, task->bucket_bmap);
+ } else {
+ itnode->state[task->id] = curmask;
+
+ /* Update bitmap */
+ set_bit(bnum, task->bucket_bmap);
+ }
+ } else if (!found) {
+ if (!evtmask)
+ goto done;
+
+ itnode = hnode_init(uuid, idx);
+ if (!itnode)
+ return 1;
+
+ itnode->state[task->id] = evtmask | DUET_MASK_VALID;
+ hlist_bl_add_head(&itnode->node, b);
+
+ /* Update bitmap */
+ set_bit(bnum, task->bucket_bmap);
+ }
+
+done:
+ hlist_bl_unlock(b);
+ local_irq_restore(flags);
+ return 0;
+}
+
+/* Fetch one item for a given task. Return found (1), empty (0), error (-1) */
+int hash_fetch(struct duet_task *task, struct duet_item *itm)
+{
+ int found;
+ unsigned long bnum, flags;
+ struct hlist_bl_head *b;
+ struct hlist_bl_node *n;
+ struct item_hnode *itnode;
+
+ local_irq_save(flags);
+again:
+ spin_lock(&task->bbmap_lock);
+ bnum = find_next_bit(task->bucket_bmap, duet_env.itm_hash_size,
+ task->bmap_cursor);
+
+ if (bnum == duet_env.itm_hash_size) {
+ /* Reached end of bitmap */
+ found = 0;
+
+ if (task->bmap_cursor != 0) {
+ /* Started part way, try again */
+ bnum = find_next_bit(task->bucket_bmap,
+ task->bmap_cursor, 0);
+
+ if (bnum != task->bmap_cursor)
+ found = 1;
+ }
+
+ if (!found) {
+ spin_unlock(&task->bbmap_lock);
+ local_irq_restore(flags);
+ return 1;
+ }
+ }
+
+ task->bmap_cursor = bnum;
+ clear_bit(bnum, task->bucket_bmap);
+ spin_unlock(&task->bbmap_lock);
+ b = duet_env.itm_hash_table + bnum;
+
+ /* Grab first item from bucket */
+ hlist_bl_lock(b);
+ if (!b->first) {
+ pr_err("duet: empty hash bucket marked in bitmap\n");
+ hlist_bl_unlock(b);
+ goto again;
+ }
+
+ found = 0;
+ hlist_bl_for_each_entry(itnode, n, b, node) {
+ if (itnode->state[task->id] & DUET_MASK_VALID) {
+ *itm = itnode->item;
+ itm->uuid.tid = task->id;
+ itm->state = itnode->state[task->id] &
+ (~DUET_MASK_VALID);
+
+ itnode->refcount--;
+ /* Free or update node */
+ if (!itnode->refcount) {
+ hlist_bl_del(n);
+ hnode_destroy(itnode);
+ } else {
+ itnode->state[task->id] = 0;
+ }
+
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found) {
+ hlist_bl_unlock(b);
+ goto again;
+ }
+
+ /* Are we still interested in this bucket? */
+ found = 0;
+ hlist_bl_for_each_entry(itnode, n, b, node) {
+ if (itnode->state[task->id] & DUET_MASK_VALID) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (found)
+ set_bit(bnum, task->bucket_bmap);
+
+ hlist_bl_unlock(b);
+ local_irq_restore(flags);
+ return 0;
+}
+
+/* Warning: expensive printing function. Use with care. */
+void hash_print(struct duet_task *task)
+{
+ unsigned long loop, count, start, end, buckets, flags;
+ unsigned long long nodes, tnodes;
+ struct hlist_bl_head *b;
+ struct hlist_bl_node *n;
+ struct item_hnode *itnode;
+
+ count = duet_env.itm_hash_size / 100;
+ tnodes = nodes = buckets = start = end = 0;
+ pr_info("duet: Printing hash table\n");
+ for (loop = 0; loop < duet_env.itm_hash_size; loop++) {
+ if (loop - start >= count) {
+ pr_info("duet: Buckets %lu - %lu: %llu nodes (task: %llu)\n",
+ start, end, nodes, tnodes);
+ start = end = loop;
+ nodes = tnodes = 0;
+ }
+
+ /* Count bucket nodes */
+ b = duet_env.itm_hash_table + loop;
+ local_irq_save(flags);
+ hlist_bl_lock(b);
+ hlist_bl_for_each_entry(itnode, n, b, node) {
+ nodes++;
+ if (itnode->state[task->id] & DUET_MASK_VALID)
+ tnodes++;
+ }
+ hlist_bl_unlock(b);
+ local_irq_restore(flags);
+
+ end = loop;
+ }
+
+ if (start != loop - 1)
+ pr_info("duet: Buckets %lu - %lu: %llu nodes (task: %llu)\n",
+ start, end, nodes, tnodes);
+}
diff --git a/mm/duet/hook.c b/mm/duet/hook.c
new file mode 100644
index 0000000..3ac89f5
--- /dev/null
+++ b/mm/duet/hook.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include "common.h"
+
+/* Handle an event. We're in RCU context so whatever happens, stay awake! */
+void duet_hook(__u16 evtcode, void *data)
+{
+ struct page *page = NULL;
+ struct inode *inode = NULL;
+ struct duet_task *cur;
+ unsigned long page_idx = 0;
+ struct duet_uuid uuid;
+
+ /* Duet must be online */
+ if (!duet_online())
+ return;
+
+ /* Handle page event */
+ page = (struct page *)data;
+
+ /* Duet must be online, and the page must belong to a valid mapping */
+ if (!page || !page_mapping(page)) {
+ duet_dbg("duet: dropped event %x due to NULL mapping\n",
+ evtcode);
+ return;
+ }
+
+ inode = page_mapping(page)->host;
+ page_idx = page->index;
+
+ /* Check that we're referring to an actual inode and get its UUID */
+ if (!inode)
+ return;
+
+ uuid.ino = inode->i_ino;
+ uuid.gen = inode->i_generation;
+
+ /* Verify that the inode does not belong to a special file */
+ if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
+ return;
+
+ if (!inode->i_ino) {
+ pr_err("duet: inode not initialized\n");
+ return;
+ }
+
+ /* Look for tasks interested in this event type and invoke callbacks */
+ rcu_read_lock();
+ list_for_each_entry_rcu(cur, &duet_env.tasks, task_list) {
+ struct super_block *sb = cur->regpath->mnt->mnt_sb;
+
+ /* Verify that the event refers to the fs we're interested in */
+ if (sb && sb != inode->i_sb)
+ continue;
+
+ duet_dbg("duet: rcvd event %x on (ino %lu, gen %lu, idx %lu)\n",
+ evtcode, uuid.ino, uuid.gen, page_idx);
+
+ /* Use the inode bitmap to filter out event if applicable */
+ if (bittree_check_inode(&cur->bittree, cur, inode) == 1)
+ continue;
+
+ /* Update the hash table */
+ if (hash_add(cur, uuid, page_idx, evtcode, 0))
+ pr_err("duet: hash table add failed\n");
+
+ wake_up(&cur->event_queue);
+ }
+ rcu_read_unlock();
+}
diff --git a/mm/duet/init.c b/mm/duet/init.c
new file mode 100644
index 0000000..a9e5ea1
--- /dev/null
+++ b/mm/duet/init.c
@@ -0,0 +1,172 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include "common.h"
+#include "syscall.h"
+
+struct duet_info duet_env;
+duet_hook_t *duet_hook_fp;
+EXPORT_SYMBOL(duet_hook_fp);
+
+int duet_online(void)
+{
+ return (atomic_read(&duet_env.status) == DUET_STATUS_ON);
+}
+
+int duet_bootstrap(__u16 numtasks)
+{
+ if (atomic_cmpxchg(&duet_env.status, DUET_STATUS_OFF, DUET_STATUS_INIT)
+ != DUET_STATUS_OFF) {
+ pr_err("duet: framework on, bootstrap aborted\n");
+ return 1;
+ }
+
+ duet_env.numtasks = (numtasks ? numtasks : DUET_DEF_NUMTASKS);
+
+ /* Initialize global hash table */
+ if (hash_init()) {
+ pr_err("duet: failed to initialize hash table\n");
+ return 1;
+ }
+
+ /* Initialize task list */
+ INIT_LIST_HEAD(&duet_env.tasks);
+ mutex_init(&duet_env.task_list_mutex);
+ atomic_set(&duet_env.status, DUET_STATUS_ON);
+
+ rcu_assign_pointer(duet_hook_fp, duet_hook);
+ synchronize_rcu();
+ return 0;
+}
+
+int duet_shutdown(void)
+{
+ struct duet_task *task;
+
+ if (atomic_cmpxchg(&duet_env.status, DUET_STATUS_ON, DUET_STATUS_CLEAN)
+ != DUET_STATUS_ON) {
+ pr_err("duet: framework off, shutdown aborted\n");
+ return 1;
+ }
+
+ rcu_assign_pointer(duet_hook_fp, NULL);
+ synchronize_rcu();
+
+ /* Remove all tasks */
+ mutex_lock(&duet_env.task_list_mutex);
+ while (!list_empty(&duet_env.tasks)) {
+ task = list_entry_rcu(duet_env.tasks.next, struct duet_task,
+ task_list);
+ list_del_rcu(&task->task_list);
+ mutex_unlock(&duet_env.task_list_mutex);
+
+ /* Make sure everyone's let go before we free it */
+ synchronize_rcu();
+ wait_event(task->cleaner_queue,
+ atomic_read(&task->refcount) == 0);
+ duet_task_dispose(task);
+
+ mutex_lock(&duet_env.task_list_mutex);
+ }
+ mutex_unlock(&duet_env.task_list_mutex);
+
+ /* Destroy global hash table */
+ vfree((void *)duet_env.itm_hash_table);
+
+ INIT_LIST_HEAD(&duet_env.tasks);
+ mutex_destroy(&duet_env.task_list_mutex);
+ atomic_set(&duet_env.status, DUET_STATUS_OFF);
+ return 0;
+}
+
+SYSCALL_DEFINE2(duet_status, u16, flags, struct duet_status_args __user *, arg)
+{
+ int ret = 0;
+ struct duet_status_args *sa;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ sa = memdup_user(arg, sizeof(*sa));
+ if (IS_ERR(sa))
+ return PTR_ERR(sa);
+
+ /* For now, we only support one struct size */
+ if (sa->size != sizeof(*sa)) {
+ pr_err("duet_status: invalid args struct size (%u)\n",
+ sa->size);
+ ret = -EINVAL;
+ goto done;
+ }
+
+ /* If we're cleaning up, only allow ops that affect Duet status */
+ if (atomic_read(&duet_env.status) != DUET_STATUS_ON && !(flags &
+ (DUET_STATUS_START | DUET_STATUS_STOP | DUET_STATUS_REPORT))) {
+ pr_err("duet_status: ops rejected during shutdown\n");
+ ret = -EINVAL;
+ goto done;
+ }
+
+ switch (flags) {
+ case DUET_STATUS_START:
+ ret = duet_bootstrap(sa->maxtasks);
+
+ if (ret)
+ pr_err("duet: failed to enable framework\n");
+ else
+ pr_info("duet: framework enabled\n");
+
+ break;
+
+ case DUET_STATUS_STOP:
+ ret = duet_shutdown();
+
+ if (ret)
+ pr_err("duet: failed to disable framework\n");
+ else
+ pr_info("duet: framework disabled\n");
+
+ break;
+
+ case DUET_STATUS_REPORT:
+ ret = duet_online();
+ break;
+
+ case DUET_STATUS_PRINT_BMAP:
+ ret = duet_print_bmap(sa->id);
+ break;
+
+ case DUET_STATUS_PRINT_ITEM:
+ ret = duet_print_item(sa->id);
+ break;
+
+ case DUET_STATUS_PRINT_LIST:
+ ret = duet_print_list(arg);
+ goto done;
+
+ default:
+ pr_info("duet_status: invalid flags\n");
+ ret = -EINVAL;
+ goto done;
+ }
+
+ if (copy_to_user(arg, sa, sizeof(*sa))) {
+ pr_err("duet_status: copy_to_user failed\n");
+ ret = -EINVAL;
+ goto done;
+ }
+
+done:
+ kfree(sa);
+ return ret;
+}
diff --git a/mm/duet/path.c b/mm/duet/path.c
new file mode 100644
index 0000000..103ab42
--- /dev/null
+++ b/mm/duet/path.c
@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include "common.h"
+#include "syscall.h"
+
+/* Scan through the page cache for a given inode */
+static int find_get_inode(struct super_block *sb, struct duet_uuid c_uuid,
+ struct inode **c_inode)
+{
+ struct inode *inode = NULL;
+
+ *c_inode = NULL;
+ spin_lock(&sb->s_inode_list_lock);
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ spin_lock(&inode->i_lock);
+ if (!*c_inode && inode->i_ino == c_uuid.ino &&
+ inode->i_generation == c_uuid.gen &&
+ !(inode->i_state & DUET_INODE_FREEING)) {
+ atomic_inc(&inode->i_count);
+ *c_inode = inode;
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&sb->s_inode_list_lock);
+ return 0;
+ }
+ spin_unlock(&inode->i_lock);
+ }
+ spin_unlock(&sb->s_inode_list_lock);
+
+ /* We shouldn't get here unless we failed */
+ return 1;
+}
+
+int do_find_path(struct duet_task *task, struct inode *inode, int getpath,
+ char *buf, int bufsize)
+{
+ int len;
+ char *p;
+ struct path path;
+ struct dentry *alias, *i_dentry = NULL;
+
+ if (!task) {
+ pr_err("do_find_path: invalid task\n");
+ return -EINVAL;
+ }
+
+ if (getpath)
+ buf[0] = '\0';
+
+ /* Get the path for at least one alias of the inode */
+ if (hlist_empty(&inode->i_dentry))
+ return -ENOENT;
+
+ hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
+ if (IS_ROOT(alias) && (alias->d_flags & DCACHE_DISCONNECTED))
+ continue;
+
+ i_dentry = alias;
+
+ /* Now get the path */
+ len = PATH_MAX;
+ memset(task->pathbuf, 0, len);
+ path.mnt = task->regpath->mnt;
+ path.dentry = i_dentry;
+
+ p = d_path(&path, task->pathbuf, len);
+ if (IS_ERR(p)) {
+ pr_err("do_find_path: d_path failed\n");
+ continue;
+ } else if (!p) {
+ duet_dbg("do_find_path: dentry not found\n");
+ continue;
+ }
+
+ /* Is this path of interest? */
+ if (memcmp(task->regpathname, p, task->regpathlen - 1)) {
+ duet_dbg("do_find_path: no common ancestor\n");
+ continue;
+ }
+
+ /* Got one. If it fits, return it */
+ if (getpath && (bufsize < len - (p - task->pathbuf)))
+ return -ENOMEM;
+
+ duet_dbg("do_find_path: got %s\n", p);
+ if (getpath)
+ memcpy(buf, p, len - (p - task->pathbuf));
+
+ return 0;
+ }
+
+ /* We only get here if we got nothing */
+ return -ENOENT;
+}
+
+int duet_find_path(struct duet_task *task, struct duet_uuid uuid, int getpath,
+ char *buf, int bufsize)
+{
+ int ret = 0;
+ struct inode *ino;
+
+ if (!task) {
+ pr_err("duet_find_path: invalid task\n");
+ return -EINVAL;
+ }
+
+ /* First, we need to find struct inode for child and parent */
+ if (find_get_inode(task->regpath->mnt->mnt_sb, uuid, &ino)) {
+ duet_dbg("duet_find_path: child inode not found\n");
+ return -ENOENT;
+ }
+
+ ret = do_find_path(task, ino, getpath, buf, bufsize);
+
+ iput(ino);
+ return ret;
+}
+
+SYSCALL_DEFINE3(duet_get_path, struct duet_uuid_arg __user *, uuid,
+ char __user *, pathbuf, int, pathbufsize)
+{
+ int ret = 0;
+ struct duet_uuid_arg *ua;
+ struct duet_task *task;
+ char *buf;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (!duet_online())
+ return -ESRCH;
+
+ /* Do some basic sanity checking */
+ if (!uuid || pathbufsize <= 0)
+ return -EINVAL;
+
+ buf = kcalloc(pathbufsize, sizeof(char), GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ ua = memdup_user(uuid, sizeof(*uuid));
+ if (IS_ERR(ua)) {
+ kfree(buf);
+ return PTR_ERR(ua);
+ }
+
+ /* For now, we only support one struct size */
+ if (ua->size != sizeof(*ua)) {
+ pr_err("duet_get_path: invalid args struct size (%u)\n",
+ ua->size);
+ ret = -EINVAL;
+ goto done;
+ }
+
+ task = duet_find_task(ua->uuid.tid);
+ if (!task) {
+ ret = -ENOENT;
+ goto done;
+ }
+
+ ret = duet_find_path(task, ua->uuid, 1, buf, pathbufsize);
+
+ if (!ret && copy_to_user(pathbuf, buf, pathbufsize))
+ ret = -EFAULT;
+
+ /* decref and wake up cleaner if needed */
+ if (atomic_dec_and_test(&task->refcount))
+ wake_up(&task->cleaner_queue);
+
+done:
+ kfree(ua);
+ kfree(buf);
+ return ret;
+}
diff --git a/mm/duet/syscall.h b/mm/duet/syscall.h
new file mode 100644
index 0000000..1bc6830
--- /dev/null
+++ b/mm/duet/syscall.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include "common.h"
+
+/* Status syscall flags */
+#define DUET_STATUS_START 0x0001
+#define DUET_STATUS_STOP 0x0002
+#define DUET_STATUS_REPORT 0x0004
+#define DUET_STATUS_PRINT_BMAP 0x0008
+#define DUET_STATUS_PRINT_ITEM 0x0010
+#define DUET_STATUS_PRINT_LIST 0x0020
+
+struct duet_task_attrs {
+ __u8 id;
+ int fd;
+ char name[NAME_MAX];
+ __u32 regmask;
+ char path[PATH_MAX];
+};
+
+struct duet_status_args {
+ __u32 size; /* in */
+ union {
+ /* DUET_START args */
+ struct {
+ __u16 maxtasks; /* in */
+ };
+
+ /* DUET_PRINT_BIT, DUET_PRINT_ITEM args */
+ struct {
+ __u8 id; /* in */
+ };
+
+ /* DUET_PRINT_LIST args */
+ struct {
+ __u16 numtasks; /* out */
+ struct duet_task_attrs tasks[0]; /* out */
+ };
+ };
+};
+
+/* Bmap syscall flags */
+#define DUET_BMAP_SET 0x0001
+#define DUET_BMAP_RESET 0x0002
+#define DUET_BMAP_CHECK 0x0004
+
+struct duet_uuid_arg {
+ __u32 size;
+ struct duet_uuid uuid;
+};
diff --git a/mm/duet/task.c b/mm/duet/task.c
new file mode 100644
index 0000000..c91fad3
--- /dev/null
+++ b/mm/duet/task.c
@@ -0,0 +1,584 @@
+/*
+ * Copyright (C) 2016 George Amvrosiadis. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 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.
+ */
+
+#include <linux/namei.h>
+#include <linux/anon_inodes.h>
+#include "common.h"
+#include "syscall.h"
+
+/*
+ * To synchronize access to the task list and structures without compromising
+ * scalability, a two-level approach is used. At the task list level, which is
+ * rarely updated, RCU is used. For the task structures, we use traditional
+ * reference counting. The two techniques are interweaved to achieve overall
+ * consistency.
+ */
+
+static unsigned int duet_poll(struct file *file, poll_table *wait)
+{
+ __u8 *tid = file->private_data;
+ struct duet_task *task;
+ int ret = 0;
+
+ task = duet_find_task(*tid);
+ if (!task) {
+ pr_err("duet_poll: task not found\n");
+ return ret;
+ }
+
+ poll_wait(file, &task->event_queue, wait);
+ if (bitmap_weight(task->bucket_bmap, duet_env.itm_hash_size))
+ ret = POLLIN | POLLRDNORM;
+
+ return ret;
+}
+
+/*
+ * Copy an item to user space, returning how much we copied.
+ *
+ * We already checked that the event size is smaller than the
+ * buffer we had in duet_read() below.
+ */
+static ssize_t copy_item_to_user(struct duet_task *task,
+ struct duet_item *item,
+ char __user *buf)
+{
+ size_t item_size = sizeof(struct duet_item);
+
+ /* Send the item */
+ if (copy_to_user(buf, item, item_size))
+ return -EFAULT;
+
+ buf += item_size;
+
+ duet_dbg("duet_read: sending (ino%lu, gen%u, idx%lu, %x)\n",
+ item->uuid.ino, item->uuid.gen, item->idx, item->state);
+
+ return item_size;
+}
+
+/*
+ * Sends out duet items. The number of bytes returned corresponds to the number
+ * of sizeof(struct duet_item) items fetched. Items are checked against the
+ * bitmap, and discarded if they have been marked; this can happen because an
+ * insertion can occur between the last read and the last bitmap set operation.
+ */
+static ssize_t duet_read(struct file *file, char __user *buf,
+ size_t count, loff_t *pos)
+{
+ struct duet_task *task;
+ struct duet_item item;
+ char __user *start;
+ int ret, err;
+ __u8 *tid;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+ start = buf;
+ tid = file->private_data;
+
+ task = duet_find_task(*tid);
+ if (!task)
+ return -ENOENT;
+
+ add_wait_queue(&task->event_queue, &wait);
+ while (1) {
+ /* Fetch an item only if there's space to store it */
+ if (sizeof(struct duet_item) > count)
+ err = -EINVAL;
+ else
+ err = hash_fetch(task, &item);
+
+ if (!err) {
+ ret = copy_item_to_user(task, &item, buf);
+ if (ret < 0)
+ break;
+ buf += ret;
+ count -= ret;
+ continue;
+ }
+
+ ret = -EAGAIN;
+ if (file->f_flags & O_NONBLOCK)
+ break;
+ ret = -ERESTARTSYS;
+ if (signal_pending(current))
+ break;
+
+ if (start != buf)
+ break;
+
+ wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+ }
+ remove_wait_queue(&task->event_queue, &wait);
+
+ if (start != buf && ret != -EFAULT)
+ ret = buf - start;
+
+ /* Decref and wake up cleaner if needed */
+ if (atomic_dec_and_test(&task->refcount))
+ wake_up(&task->cleaner_queue);
+
+ return ret;
+}
+
+/*
+ * Properly dismantle and dispose of a task struct.
+ * At this point we've guaranteed that noone else is accessing the
+ * task struct, so we don't need any locks
+ */
+void duet_task_dispose(struct duet_task *task)
+{
+ int ret = 0;
+ struct duet_item itm;
+
+ /* Dispose of the bitmap tree */
+ bittree_destroy(&task->bittree);
+
+ /* Dispose of hash table entries, bucket bitmap */
+ while (!ret)
+ ret = hash_fetch(task, &itm);
+ kfree(task->bucket_bmap);
+
+ putname(task->name);
+ path_put(task->regpath);
+ kfree(task->regpath);
+ kfree(task->regpathname);
+ kfree(task->pathbuf);
+ kfree(task);
+}
+
+static int duet_release(struct inode *ignored, struct file *file)
+{
+ __u8 *tid = file->private_data;
+ struct duet_task *cur;
+
+ /* Find the task in the list, then dispose of it */
+ mutex_lock(&duet_env.task_list_mutex);
+ list_for_each_entry_rcu(cur, &duet_env.tasks, task_list) {
+ if (cur->id == *tid) {
+#ifdef CONFIG_DUET_STATS
+ hash_print(cur);
+ bittree_print(cur);
+#endif /* CONFIG_DUET_STATS */
+ list_del_rcu(&cur->task_list);
+ mutex_unlock(&duet_env.task_list_mutex);
+
+ /* Wait until everyone's done with it */
+ synchronize_rcu();
+ wait_event(cur->cleaner_queue,
+ atomic_read(&cur->refcount) == 0);
+
+ pr_info("duet: deregistered task %d\n", cur->id);
+
+ duet_task_dispose(cur);
+ kfree(tid);
+ return 0;
+ }
+ }
+ mutex_unlock(&duet_env.task_list_mutex);
+
+ return -ENOENT;
+}
+
+static const struct file_operations duet_fops = {
+ .show_fdinfo = NULL,
+ .poll = duet_poll,
+ .read = duet_read,
+ .fasync = NULL,
+ .release = duet_release,
+ .unlocked_ioctl = NULL,
+ .compat_ioctl = NULL,
+ .llseek = noop_llseek,
+};
+
+static int process_inode(struct duet_task *task, struct inode *inode)
+{
+ struct radix_tree_iter iter;
+ struct duet_uuid uuid;
+ void **slot;
+ __u16 state;
+
+ /* Use the inode bitmap to decide whether to skip inode */
+ if (bittree_check_inode(&task->bittree, task, inode) == 1)
+ return 0;
+
+ /* Go through all pages of this inode */
+ rcu_read_lock();
+ radix_tree_for_each_slot(slot, &inode->i_mapping->page_tree, &iter, 0) {
+ struct page *page;
+
+ page = radix_tree_deref_slot(slot);
+ if (unlikely(!page))
+ continue;
+
+ if (radix_tree_exception(page)) {
+ if (radix_tree_deref_retry(page)) {
+ slot = radix_tree_iter_retry(&iter);
+ continue;
+ }
+ /*
+ * Shadow entry of recently evicted page, or swap entry
+ * from shmem/tmpfs. Skip over it.
+ */
+ continue;
+ }
+
+ state = DUET_PAGE_ADDED;
+ if (PageDirty(page))
+ state |= DUET_PAGE_DIRTY;
+ uuid.ino = inode->i_ino;
+ uuid.gen = inode->i_generation;
+ hash_add(task, uuid, page->index, state, 1);
+ }
+ rcu_read_unlock();
+
+ return 0;
+}
+
+/* Scan through the page cache for events of interest to the task */
+static int scan_page_cache(struct duet_task *task)
+{
+ struct inode *inode, *prev = NULL;
+ struct super_block *sb = task->regpath->mnt->mnt_sb;
+
+ pr_info("duet: page cache scan started\n");
+
+ spin_lock(&sb->s_inode_list_lock);
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ struct address_space *mapping = inode->i_mapping;
+
+ spin_lock(&inode->i_lock);
+ if (inode->i_state & DUET_INODE_FREEING ||
+ mapping->nrpages == 0) {
+ spin_unlock(&inode->i_lock);
+ continue;
+ }
+ atomic_inc(&inode->i_count);
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&sb->s_inode_list_lock);
+
+ /*
+ * We are holding a reference to inode so it won't be removed
+ * from s_inodes list while we don't hold the s_inode_list_lock.
+ * We cannot iput the inode now, though, as we may be holding
+ * the last reference. We will iput it after the iteration is
+ * done.
+ */
+
+ iput(prev);
+ prev = inode;
+
+ process_inode(task, inode);
+
+ spin_lock(&sb->s_inode_list_lock);
+ }
+ spin_unlock(&sb->s_inode_list_lock);
+ iput(prev);
+
+ pr_info("duet: page cache scan finished\n");
+
+ return 0;
+}
+
+/* Find task and increment its refcount */
+struct duet_task *duet_find_task(__u8 id)
+{
+ struct duet_task *cur, *task = NULL;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(cur, &duet_env.tasks, task_list) {
+ if (cur->id == id) {
+ task = cur;
+ atomic_inc(&task->refcount);
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return task;
+}
+
+/* Allocate and initialize a task struct */
+static int duet_task_init(struct duet_task **task, struct filename *name,
+ __u32 regmask, struct path *path)
+{
+ int len;
+ char *p;
+ u32 evtmask = regmask;
+
+ /* Do some sanity checking on event mask. */
+ if (evtmask & DUET_PAGE_EXISTS) {
+ if (evtmask & (DUET_PAGE_ADDED | DUET_PAGE_REMOVED)) {
+ pr_debug("duet_task_init: invalid regmask\n");
+ return -EINVAL;
+ }
+ evtmask |= (DUET_PAGE_ADDED | DUET_PAGE_REMOVED);
+ }
+
+ if (evtmask & DUET_PAGE_MODIFIED) {
+ if (evtmask & (DUET_PAGE_DIRTY | DUET_PAGE_FLUSHED)) {
+ pr_debug("duet_task_init: invalid regmask\n");
+ goto err;
+ }
+ evtmask |= (DUET_PAGE_DIRTY | DUET_PAGE_FLUSHED);
+ }
+
+ /* Allocate task info struct */
+ *task = kzalloc(sizeof(**task), GFP_KERNEL);
+ if (!(*task))
+ return -ENOMEM;
+
+ /* Allocate temporary space for getpath file paths */
+ (*task)->pathbuf = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (!(*task)->pathbuf) {
+ pr_err("duet_task_init: buffer allocation failed\n");
+ kfree(*task);
+ return -ENOMEM;
+ }
+
+ /* Find and store registered dir path */
+ (*task)->regpathname = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (!(*task)->regpathname) {
+ pr_err("duet_task_init: path allocation failed\n");
+ kfree((*task)->pathbuf);
+ kfree(*task);
+ return -ENOMEM;
+ }
+
+ /* Populate registered dir path buffer */
+ len = PATH_MAX;
+ p = d_path(path, (*task)->pathbuf, len);
+ if (IS_ERR(p)) {
+ pr_err("duet_task_init: path registration failed\n");
+ goto err;
+ } else if (!p) {
+ pr_err("duet_task_init: (null) registered path\n");
+ goto err;
+ }
+
+ (*task)->regpathlen = len - (p - (*task)->pathbuf);
+ memcpy((*task)->regpathname, p, (*task)->regpathlen);
+
+ (*task)->id = 1;
+ (*task)->name = name;
+ (*task)->regpath = path;
+ (*task)->evtmask = (regmask & 0xffff);
+ atomic_set(&(*task)->refcount, 0);
+ INIT_LIST_HEAD(&(*task)->task_list);
+ init_waitqueue_head(&(*task)->cleaner_queue);
+ init_waitqueue_head(&(*task)->event_queue);
+ bittree_init(&(*task)->bittree);
+
+ /* Initialize hash table bitmap */
+ (*task)->bmap_cursor = 0;
+ spin_lock_init(&(*task)->bbmap_lock);
+ (*task)->bucket_bmap = kzalloc(sizeof(unsigned long) *
+ BITS_TO_LONGS(duet_env.itm_hash_size), GFP_KERNEL);
+ if (!(*task)->bucket_bmap) {
+ pr_err("duet_task_init: hash bitmap alloc failed\n");
+ kfree((*task)->regpathname);
+ kfree((*task)->pathbuf);
+ kfree(*task);
+ return -ENOMEM;
+ }
+
+ return 0;
+err:
+ pr_err("duet_task_init: error registering task\n");
+ kfree((*task)->regpathname);
+ kfree((*task)->pathbuf);
+ kfree(*task);
+ return -EINVAL;
+}
+
+/* Register the task with Duet */
+int duet_register_task(struct filename *name, __u32 regmask, struct path *path)
+{
+ int ret;
+ __u8 *tid;
+ struct duet_task *cur, *task = NULL;
+ struct list_head *last;
+
+ /* Do some sanity checking on the parameters passed */
+ if (!path || !regmask)
+ return -EINVAL;
+
+ if (!path->dentry || !path->dentry->d_inode) {
+ pr_err("duet_register_task: invalid path\n");
+ return -EINVAL;
+ }
+
+ if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
+ pr_err("duet_register_task: path is not a dir\n");
+ return -EINVAL;
+ }
+
+ ret = duet_task_init(&task, name, regmask, path);
+ if (ret) {
+ pr_err("duet_register_task: initialization failed\n");
+ return ret;
+ }
+
+ /* Now get an anonymous inode to use for communication with Duet */
+ tid = kzalloc(sizeof(__u8), GFP_KERNEL);
+ if (!tid) {
+ duet_task_dispose(task);
+ return -ENOMEM;
+ }
+
+ ret = anon_inode_getfd("duet", &duet_fops, tid,
+ O_RDONLY | ((regmask & DUET_FD_NONBLOCK) ? O_NONBLOCK : 0));
+ if (ret < 0) {
+ duet_task_dispose(task);
+ kfree(tid);
+ return ret;
+ }
+
+ task->fd = ret;
+
+ /* Find a free task id for the new task. Tasks are sorted by id. */
+ mutex_lock(&duet_env.task_list_mutex);
+ last = &duet_env.tasks;
+ list_for_each_entry_rcu(cur, &duet_env.tasks, task_list) {
+ if (cur->id == task->id)
+ (task->id)++;
+ else if (cur->id > task->id)
+ break;
+
+ last = &cur->task_list;
+ }
+ list_add_rcu(&task->task_list, last);
+ mutex_unlock(&duet_env.task_list_mutex);
+
+ *tid = task->id;
+
+ /* Before we return, scan the page cache for pages of interest */
+ scan_page_cache(task);
+
+ pr_info("duet: task %d (fd %d) registered %s(%d) with mask %x\n",
+ task->id, task->fd, task->regpathname, task->regpathlen,
+ task->evtmask);
+
+ return ret;
+}
+
+SYSCALL_DEFINE3(duet_init, const char __user *, taskname, u32, regmask,
+ const char __user *, pathname)
+{
+ int ret;
+ unsigned int lookup_flags = LOOKUP_DIRECTORY;
+ struct filename *name = NULL;
+ struct path *path = NULL;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (!duet_online())
+ return -ESRCH;
+
+ /* Do some basic sanity checking */
+ if (!pathname || !regmask)
+ return -EINVAL;
+
+ if (taskname) {
+ name = getname(taskname);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+ }
+
+ path = kzalloc(sizeof(struct path), GFP_KERNEL);
+ if (!path) {
+ putname(name);
+ return -ENOMEM;
+ }
+
+ ret = user_path_at(AT_FDCWD, pathname, lookup_flags, path);
+ if (ret) {
+ pr_err("duet_init: user_path_at failed\n");
+ goto err;
+ }
+
+ /* Register the task with the framework */
+ ret = duet_register_task(name, regmask, path);
+ if (ret < 0) {
+ pr_err("duet_init: task registration failed\n");
+ goto err;
+ }
+
+ return ret;
+
+err:
+ putname(name);
+ path_put(path);
+ kfree(path);
+ return ret;
+}
+
+SYSCALL_DEFINE2(duet_bmap, u16, flags, struct duet_uuid_arg __user *, arg)
+{
+ int ret = 0;
+ struct duet_uuid_arg *ua;
+ struct duet_task *task;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (!duet_online())
+ return -ESRCH;
+
+ /* Do some basic sanity checking */
+ if (!arg)
+ return -EINVAL;
+
+ ua = memdup_user(arg, sizeof(*arg));
+ if (IS_ERR(ua))
+ return PTR_ERR(ua);
+
+ /* For now, we only support one struct size */
+ if (ua->size != sizeof(*ua)) {
+ pr_err("duet_bmap: invalid args struct size (%u)\n", ua->size);
+ ret = -EINVAL;
+ goto done;
+ }
+
+ task = duet_find_task(ua->uuid.tid);
+ if (!task)
+ return -ENOENT;
+
+ switch (flags) {
+ case DUET_BMAP_SET:
+ ret = bittree_set(&task->bittree, ua->uuid);
+ break;
+
+ case DUET_BMAP_RESET:
+ ret = bittree_reset(&task->bittree, ua->uuid);
+ break;
+
+ case DUET_BMAP_CHECK:
+ ret = bittree_check(&task->bittree, ua->uuid, task);
+ break;
+
+ default:
+ pr_err("duet_bmap: invalid flags\n");
+ ret = -EINVAL;
+ break;
+ }
+
+ /* decreg and wake up cleaner if needed */
+ if (atomic_dec_and_test(&task->refcount))
+ wake_up(&task->cleaner_queue);
+
+done:
+ kfree(ua);
+ return ret;
+}
--
2.7.4
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