/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
- * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
#include "glock.h"
#include "glops.h"
#include "inode.h"
-#include "lm.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
struct gfs2_sbd *sdp = gl->gl_sbd;
struct inode *aspace = gl->gl_aspace;
- gfs2_lm_put_lock(sdp, gl->gl_lock);
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ sdp->sd_lockstruct.ls_ops->lm_put_lock(gl->gl_lock);
if (aspace)
gfs2_aspace_put(aspace);
*
*/
-void gfs2_glock_hold(struct gfs2_glock *gl)
+static void gfs2_glock_hold(struct gfs2_glock *gl)
{
atomic_inc(&gl->gl_ref);
}
if (atomic_dec_and_test(&gl->gl_ref)) {
hlist_del(&gl->gl_list);
write_unlock(gl_lock_addr(gl->gl_hash));
- BUG_ON(spin_is_locked(&gl->gl_spin));
gfs2_assert(sdp, gl->gl_state == LM_ST_UNLOCKED);
gfs2_assert(sdp, list_empty(&gl->gl_reclaim));
gfs2_assert(sdp, list_empty(&gl->gl_holders));
gfs2_glock_put(gl);
}
+static int gfs2_lm_get_lock(struct gfs2_sbd *sdp, struct lm_lockname *name,
+ void **lockp)
+{
+ int error = -EIO;
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ error = sdp->sd_lockstruct.ls_ops->lm_get_lock(
+ sdp->sd_lockstruct.ls_lockspace, name, lockp);
+ return error;
+}
+
/**
* gfs2_glock_get() - Get a glock, or create one if one doesn't exist
* @sdp: The GFS2 superblock
gl->gl_state = LM_ST_UNLOCKED;
gl->gl_demote_state = LM_ST_EXCLUSIVE;
gl->gl_hash = hash;
- gl->gl_owner_pid = 0;
+ gl->gl_owner_pid = NULL;
gl->gl_ip = 0;
gl->gl_ops = glops;
gl->gl_req_gh = NULL;
- gl->gl_req_bh = NULL;
- gl->gl_vn = 0;
gl->gl_stamp = jiffies;
gl->gl_tchange = jiffies;
gl->gl_object = NULL;
gl->gl_sbd = sdp;
gl->gl_aspace = NULL;
- lops_init_le(&gl->gl_le, &gfs2_glock_lops);
INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
/* If this glock protects actual on-disk data or metadata blocks,
INIT_LIST_HEAD(&gh->gh_list);
gh->gh_gl = gl;
gh->gh_ip = (unsigned long)__builtin_return_address(0);
- gh->gh_owner_pid = current->pid;
+ gh->gh_owner_pid = get_pid(task_pid(current));
gh->gh_state = state;
gh->gh_flags = flags;
gh->gh_error = 0;
void gfs2_holder_uninit(struct gfs2_holder *gh)
{
+ put_pid(gh->gh_owner_pid);
gfs2_glock_put(gh->gh_gl);
gh->gh_gl = NULL;
gh->gh_ip = 0;
static void gfs2_demote_wake(struct gfs2_glock *gl)
{
- BUG_ON(!spin_is_locked(&gl->gl_spin));
gl->gl_demote_state = LM_ST_EXCLUSIVE;
clear_bit(GLF_DEMOTE, &gl->gl_flags);
smp_mb__after_clear_bit();
static int rq_promote(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
- struct gfs2_sbd *sdp = gl->gl_sbd;
if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
if (list_empty(&gl->gl_holders)) {
gl->gl_req_gh = gh;
set_bit(GLF_LOCK, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
-
- if (atomic_read(&sdp->sd_reclaim_count) >
- gfs2_tune_get(sdp, gt_reclaim_limit) &&
- !(gh->gh_flags & LM_FLAG_PRIORITY)) {
- gfs2_reclaim_glock(sdp);
- gfs2_reclaim_glock(sdp);
- }
-
gfs2_glock_xmote_th(gh->gh_gl, gh);
spin_lock(&gl->gl_spin);
}
gfs2_demote_wake(gl);
return 0;
}
+
set_bit(GLF_LOCK, &gl->gl_flags);
+ set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
+
if (gl->gl_demote_state == LM_ST_UNLOCKED ||
gl->gl_state != LM_ST_EXCLUSIVE) {
spin_unlock(&gl->gl_spin);
spin_unlock(&gl->gl_spin);
gfs2_glock_xmote_th(gl, NULL);
}
+
spin_lock(&gl->gl_spin);
+ clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
return 0;
}
if (!list_empty(&gl->gl_waiters1)) {
gh = list_entry(gl->gl_waiters1.next,
struct gfs2_holder, gh_list);
-
- if (test_bit(HIF_MUTEX, &gh->gh_iflags))
- blocked = rq_mutex(gh);
- else
- gfs2_assert_warn(gl->gl_sbd, 0);
-
+ blocked = rq_mutex(gh);
} else if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
blocked = rq_demote(gl);
+ if (test_bit(GLF_WAITERS2, &gl->gl_flags) &&
+ !blocked) {
+ set_bit(GLF_DEMOTE, &gl->gl_flags);
+ gl->gl_demote_state = LM_ST_UNLOCKED;
+ }
+ clear_bit(GLF_WAITERS2, &gl->gl_flags);
} else if (!list_empty(&gl->gl_waiters3)) {
gh = list_entry(gl->gl_waiters3.next,
struct gfs2_holder, gh_list);
-
- if (test_bit(HIF_PROMOTE, &gh->gh_iflags))
- blocked = rq_promote(gh);
- else
- gfs2_assert_warn(gl->gl_sbd, 0);
-
+ blocked = rq_promote(gh);
} else
break;
static void gfs2_glmutex_lock(struct gfs2_glock *gl)
{
- struct gfs2_holder gh;
-
- gfs2_holder_init(gl, 0, 0, &gh);
- set_bit(HIF_MUTEX, &gh.gh_iflags);
- if (test_and_set_bit(HIF_WAIT, &gh.gh_iflags))
- BUG();
-
spin_lock(&gl->gl_spin);
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
+ struct gfs2_holder gh;
+
+ gfs2_holder_init(gl, 0, 0, &gh);
+ set_bit(HIF_WAIT, &gh.gh_iflags);
list_add_tail(&gh.gh_list, &gl->gl_waiters1);
+ spin_unlock(&gl->gl_spin);
+ wait_on_holder(&gh);
+ gfs2_holder_uninit(&gh);
} else {
- gl->gl_owner_pid = current->pid;
+ gl->gl_owner_pid = get_pid(task_pid(current));
gl->gl_ip = (unsigned long)__builtin_return_address(0);
- clear_bit(HIF_WAIT, &gh.gh_iflags);
- smp_mb();
- wake_up_bit(&gh.gh_iflags, HIF_WAIT);
+ spin_unlock(&gl->gl_spin);
}
- spin_unlock(&gl->gl_spin);
-
- wait_on_holder(&gh);
- gfs2_holder_uninit(&gh);
}
/**
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
acquired = 0;
} else {
- gl->gl_owner_pid = current->pid;
+ gl->gl_owner_pid = get_pid(task_pid(current));
gl->gl_ip = (unsigned long)__builtin_return_address(0);
}
spin_unlock(&gl->gl_spin);
static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
{
+ struct pid *pid;
+
spin_lock(&gl->gl_spin);
clear_bit(GLF_LOCK, &gl->gl_flags);
- gl->gl_owner_pid = 0;
+ pid = gl->gl_owner_pid;
+ gl->gl_owner_pid = NULL;
gl->gl_ip = 0;
run_queue(gl);
- BUG_ON(!spin_is_locked(&gl->gl_spin));
spin_unlock(&gl->gl_spin);
+
+ put_pid(pid);
}
/**
}
} else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != state) {
- gl->gl_demote_state = LM_ST_UNLOCKED;
+ if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
+ set_bit(GLF_WAITERS2, &gl->gl_flags);
+ else
+ gl->gl_demote_state = LM_ST_UNLOCKED;
}
spin_unlock(&gl->gl_spin);
}
gl->gl_tchange = jiffies;
}
+/**
+ * drop_bh - Called after a lock module unlock completes
+ * @gl: the glock
+ * @ret: the return status
+ *
+ * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
+ * Doesn't drop the reference on the glock the top half took out
+ *
+ */
+
+static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
+{
+ struct gfs2_sbd *sdp = gl->gl_sbd;
+ struct gfs2_holder *gh = gl->gl_req_gh;
+
+ gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
+ gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
+ gfs2_assert_warn(sdp, !ret);
+
+ state_change(gl, LM_ST_UNLOCKED);
+
+ if (test_and_clear_bit(GLF_CONV_DEADLK, &gl->gl_flags)) {
+ spin_lock(&gl->gl_spin);
+ gh->gh_error = 0;
+ spin_unlock(&gl->gl_spin);
+ gfs2_glock_xmote_th(gl, gl->gl_req_gh);
+ gfs2_glock_put(gl);
+ return;
+ }
+
+ spin_lock(&gl->gl_spin);
+ gfs2_demote_wake(gl);
+ clear_bit(GLF_LOCK, &gl->gl_flags);
+ spin_unlock(&gl->gl_spin);
+ gfs2_glock_put(gl);
+}
+
/**
* xmote_bh - Called after the lock module is done acquiring a lock
* @gl: The glock in question
struct gfs2_sbd *sdp = gl->gl_sbd;
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh = gl->gl_req_gh;
- int prev_state = gl->gl_state;
int op_done = 1;
+ if (!gh && (ret & LM_OUT_ST_MASK) == LM_ST_UNLOCKED) {
+ drop_bh(gl, ret);
+ return;
+ }
+
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
state_change(gl, ret & LM_OUT_ST_MASK);
- if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
- if (glops->go_inval)
- glops->go_inval(gl, DIO_METADATA);
- } else if (gl->gl_state == LM_ST_DEFERRED) {
- /* We might not want to do this here.
- Look at moving to the inode glops. */
- if (glops->go_inval)
- glops->go_inval(gl, 0);
- }
-
/* Deal with each possible exit condition */
if (!gh) {
} else {
spin_lock(&gl->gl_spin);
if (gl->gl_state != gl->gl_demote_state) {
- gl->gl_req_bh = NULL;
spin_unlock(&gl->gl_spin);
gfs2_glock_drop_th(gl);
gfs2_glock_put(gl);
}
} else {
spin_lock(&gl->gl_spin);
+ if (ret & LM_OUT_CONV_DEADLK) {
+ gh->gh_error = 0;
+ set_bit(GLF_CONV_DEADLK, &gl->gl_flags);
+ spin_unlock(&gl->gl_spin);
+ gfs2_glock_drop_th(gl);
+ gfs2_glock_put(gl);
+ return;
+ }
list_del_init(&gh->gh_list);
gh->gh_error = -EIO;
if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
if (op_done) {
spin_lock(&gl->gl_spin);
gl->gl_req_gh = NULL;
- gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
}
gfs2_holder_wake(gh);
}
+static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
+ unsigned int cur_state, unsigned int req_state,
+ unsigned int flags)
+{
+ int ret = 0;
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock, cur_state,
+ req_state, flags);
+ return ret;
+}
+
/**
* gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
* @gl: The glock in question
if (glops->go_xmote_th)
glops->go_xmote_th(gl);
+ if (state == LM_ST_DEFERRED && glops->go_inval)
+ glops->go_inval(gl, DIO_METADATA);
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, state != gl->gl_state);
gfs2_glock_hold(gl);
- gl->gl_req_bh = xmote_bh;
lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state, lck_flags);
xmote_bh(gl, lck_ret);
}
-/**
- * drop_bh - Called after a lock module unlock completes
- * @gl: the glock
- * @ret: the return status
- *
- * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
- * Doesn't drop the reference on the glock the top half took out
- *
- */
-
-static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
+static unsigned int gfs2_lm_unlock(struct gfs2_sbd *sdp, void *lock,
+ unsigned int cur_state)
{
- struct gfs2_sbd *sdp = gl->gl_sbd;
- const struct gfs2_glock_operations *glops = gl->gl_ops;
- struct gfs2_holder *gh = gl->gl_req_gh;
-
- gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
- gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
- gfs2_assert_warn(sdp, !ret);
-
- state_change(gl, LM_ST_UNLOCKED);
-
- if (glops->go_inval)
- glops->go_inval(gl, DIO_METADATA);
-
- if (gh) {
- spin_lock(&gl->gl_spin);
- list_del_init(&gh->gh_list);
- gh->gh_error = 0;
- spin_unlock(&gl->gl_spin);
- }
-
- spin_lock(&gl->gl_spin);
- gfs2_demote_wake(gl);
- gl->gl_req_gh = NULL;
- gl->gl_req_bh = NULL;
- clear_bit(GLF_LOCK, &gl->gl_flags);
- spin_unlock(&gl->gl_spin);
-
- gfs2_glock_put(gl);
-
- if (gh)
- gfs2_holder_wake(gh);
+ int ret = 0;
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ ret = sdp->sd_lockstruct.ls_ops->lm_unlock(lock, cur_state);
+ return ret;
}
/**
const struct gfs2_glock_operations *glops = gl->gl_ops;
unsigned int ret;
- if (glops->go_drop_th)
- glops->go_drop_th(gl);
+ if (glops->go_xmote_th)
+ glops->go_xmote_th(gl);
+ if (glops->go_inval)
+ glops->go_inval(gl, DIO_METADATA);
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
gfs2_glock_hold(gl);
- gl->gl_req_bh = drop_bh;
ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
static void do_cancels(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
+ struct gfs2_sbd *sdp = gl->gl_sbd;
spin_lock(&gl->gl_spin);
while (gl->gl_req_gh != gh &&
!test_bit(HIF_HOLDER, &gh->gh_iflags) &&
!list_empty(&gh->gh_list)) {
- if (gl->gl_req_bh && !(gl->gl_req_gh &&
- (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
+ if (!(gl->gl_req_gh && (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
spin_unlock(&gl->gl_spin);
- gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ sdp->sd_lockstruct.ls_ops->lm_cancel(gl->gl_lock);
msleep(100);
spin_lock(&gl->gl_spin);
} else {
spin_lock(&gl->gl_spin);
gl->gl_req_gh = NULL;
- gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
run_queue(gl);
spin_unlock(&gl->gl_spin);
}
static inline struct gfs2_holder *
-find_holder_by_owner(struct list_head *head, pid_t pid)
+find_holder_by_owner(struct list_head *head, struct pid *pid)
{
struct gfs2_holder *gh;
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_holder *existing;
- BUG_ON(!gh->gh_owner_pid);
+ BUG_ON(gh->gh_owner_pid == NULL);
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
BUG();
if (existing) {
print_symbol(KERN_WARNING "original: %s\n",
existing->gh_ip);
- printk(KERN_INFO "pid : %d\n", existing->gh_owner_pid);
+ printk(KERN_INFO "pid : %d\n",
+ pid_nr(existing->gh_owner_pid));
printk(KERN_INFO "lock type : %d lock state : %d\n",
existing->gh_gl->gl_name.ln_type,
existing->gh_gl->gl_state);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
- printk(KERN_INFO "pid : %d\n", gh->gh_owner_pid);
+ printk(KERN_INFO "pid : %d\n",
+ pid_nr(gh->gh_owner_pid));
printk(KERN_INFO "lock type : %d lock state : %d\n",
gl->gl_name.ln_type, gl->gl_state);
BUG();
return -EIO;
}
- set_bit(HIF_PROMOTE, &gh->gh_iflags);
-
spin_lock(&gl->gl_spin);
add_to_queue(gh);
run_queue(gl);
list_del_init(&gh->gh_list);
if (list_empty(&gl->gl_holders)) {
- spin_unlock(&gl->gl_spin);
-
- if (glops->go_unlock)
+ if (glops->go_unlock) {
+ spin_unlock(&gl->gl_spin);
glops->go_unlock(gh);
-
- spin_lock(&gl->gl_spin);
+ spin_lock(&gl->gl_spin);
+ }
gl->gl_stamp = jiffies;
}
gfs2_glock_dq_uninit(&ghs[x]);
}
+static int gfs2_lm_hold_lvb(struct gfs2_sbd *sdp, void *lock, char **lvbp)
+{
+ int error = -EIO;
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ error = sdp->sd_lockstruct.ls_ops->lm_hold_lvb(lock, lvbp);
+ return error;
+}
+
/**
* gfs2_lvb_hold - attach a LVB from a glock
* @gl: The glock in question
void gfs2_lvb_unhold(struct gfs2_glock *gl)
{
+ struct gfs2_sbd *sdp = gl->gl_sbd;
+
gfs2_glock_hold(gl);
gfs2_glmutex_lock(gl);
gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
if (atomic_dec_and_test(&gl->gl_lvb_count)) {
- gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
+ if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ sdp->sd_lockstruct.ls_ops->lm_unhold_lvb(gl->gl_lock, gl->gl_lvb);
gl->gl_lvb = NULL;
gfs2_glock_put(gl);
}
gl = gfs2_glock_find(sdp, &async->lc_name);
if (gfs2_assert_warn(sdp, gl))
return;
- if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
- gl->gl_req_bh(gl, async->lc_ret);
+ xmote_bh(gl, async->lc_ret);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
up_read(&gfs2_umount_flush_sem);
gfs2_glock_hold(gl);
list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
atomic_inc(&sdp->sd_reclaim_count);
- }
- spin_unlock(&sdp->sd_reclaim_lock);
-
- wake_up(&sdp->sd_reclaim_wq);
+ spin_unlock(&sdp->sd_reclaim_lock);
+ wake_up(&sdp->sd_reclaim_wq);
+ } else
+ spin_unlock(&sdp->sd_reclaim_lock);
}
/**
print_dbg(gi, " %s\n", str);
if (gh->gh_owner_pid) {
- print_dbg(gi, " owner = %ld ", (long)gh->gh_owner_pid);
- gh_owner = find_task_by_pid(gh->gh_owner_pid);
+ print_dbg(gi, " owner = %ld ",
+ (long)pid_nr(gh->gh_owner_pid));
+ gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
if (gh_owner)
print_dbg(gi, "(%s)\n", gh_owner->comm);
else
print_dbg(gi, " gl_ref = %d\n", atomic_read(&gl->gl_ref));
print_dbg(gi, " gl_state = %u\n", gl->gl_state);
if (gl->gl_owner_pid) {
- gl_owner = find_task_by_pid(gl->gl_owner_pid);
+ gl_owner = pid_task(gl->gl_owner_pid, PIDTYPE_PID);
if (gl_owner)
print_dbg(gi, " gl_owner = pid %d (%s)\n",
- gl->gl_owner_pid, gl_owner->comm);
+ pid_nr(gl->gl_owner_pid), gl_owner->comm);
else
print_dbg(gi, " gl_owner = %d (ended)\n",
- gl->gl_owner_pid);
+ pid_nr(gl->gl_owner_pid));
} else
print_dbg(gi, " gl_owner = -1\n");
print_dbg(gi, " gl_ip = %lu\n", gl->gl_ip);
print_dbg(gi, " req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
- print_dbg(gi, " req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
print_dbg(gi, " lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
print_dbg(gi, " object = %s\n", (gl->gl_object) ? "yes" : "no");
- print_dbg(gi, " le = %s\n",
- (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
print_dbg(gi, " reclaim = %s\n",
(list_empty(&gl->gl_reclaim)) ? "no" : "yes");
if (gl->gl_aspace)
projects / linux-2.6-omap-h63xx.git / blobdiff