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authorIan Kent <raven@themaw.net>2018-08-21 21:59:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:49 -0700
commitcbf6898fd69455092c43cd573b38d42c86ddb1e0 (patch)
treec49426928aac298e240d2dcbca54b8231d9cfc77 /fs/autofs
parente5c85e1fe19c03777cbacf4b5a5167b2f5ff90fb (diff)
downloadlwn-cbf6898fd69455092c43cd573b38d42c86ddb1e0.tar.gz
lwn-cbf6898fd69455092c43cd573b38d42c86ddb1e0.zip
autofs: add AUTOFS_EXP_FORCED flag
The userspace automount(8) daemon is meant to perform a forced expire when sent a SIGUSR2. But since the expiration is routed through the kernel and the kernel doesn't send an expire request if the mount is busy this hasn't worked at least since autofs version 5. Add an AUTOFS_EXP_FORCED flag to allow implemention of the feature and bump the protocol version so user space can check if it's implemented if needed. Link: http://lkml.kernel.org/r/152937734715.21213.6594007182776598970.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/autofs')
-rw-r--r--fs/autofs/expire.c62
1 files changed, 50 insertions, 12 deletions
diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c
index dfb666c5b8a2..d441244b79df 100644
--- a/fs/autofs/expire.c
+++ b/fs/autofs/expire.c
@@ -29,7 +29,8 @@ static inline int autofs_can_expire(struct dentry *dentry,
}
/* Check a mount point for busyness */
-static int autofs_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
+static int autofs_mount_busy(struct vfsmount *mnt,
+ struct dentry *dentry, unsigned int how)
{
struct dentry *top = dentry;
struct path path = {.mnt = mnt, .dentry = dentry};
@@ -50,6 +51,12 @@ static int autofs_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
goto done;
}
+ /* Not a submount, has a forced expire been requested */
+ if (how & AUTOFS_EXP_FORCED) {
+ status = 0;
+ goto done;
+ }
+
/* Update the expiry counter if fs is busy */
if (!may_umount_tree(path.mnt)) {
struct autofs_info *ino;
@@ -189,6 +196,10 @@ static int autofs_direct_busy(struct vfsmount *mnt,
{
pr_debug("top %p %pd\n", top, top);
+ /* Forced expire, user space handles busy mounts */
+ if (how & AUTOFS_EXP_FORCED)
+ return 0;
+
/* If it's busy update the expiry counters */
if (!may_umount_tree(mnt)) {
struct autofs_info *ino;
@@ -235,7 +246,7 @@ static int autofs_tree_busy(struct vfsmount *mnt,
* If the fs is busy update the expiry counter.
*/
if (d_mountpoint(p)) {
- if (autofs_mount_busy(mnt, p)) {
+ if (autofs_mount_busy(mnt, p, how)) {
top_ino->last_used = jiffies;
dput(p);
return 1;
@@ -258,6 +269,10 @@ static int autofs_tree_busy(struct vfsmount *mnt,
}
}
+ /* Forced expire, user space handles busy mounts */
+ if (how & AUTOFS_EXP_FORCED)
+ return 0;
+
/* Timeout of a tree mount is ultimately determined by its top dentry */
if (!autofs_can_expire(top, timeout, how))
return 1;
@@ -280,9 +295,15 @@ static struct dentry *autofs_check_leaves(struct vfsmount *mnt,
if (d_mountpoint(p)) {
/* Can we umount this guy */
- if (autofs_mount_busy(mnt, p))
+ if (autofs_mount_busy(mnt, p, how))
continue;
+ /* This isn't a submount so if a forced expire
+ * has been requested, user space handles busy
+ * mounts */
+ if (how & AUTOFS_EXP_FORCED)
+ return p;
+
/* Can we expire this guy */
if (autofs_can_expire(p, timeout, how))
return p;
@@ -361,9 +382,15 @@ static struct dentry *should_expire(struct dentry *dentry,
pr_debug("checking mountpoint %p %pd\n", dentry, dentry);
/* Can we umount this guy */
- if (autofs_mount_busy(mnt, dentry))
+ if (autofs_mount_busy(mnt, dentry, how))
return NULL;
+ /* This isn't a submount so if a forced expire
+ * has been requested, user space handles busy
+ * mounts */
+ if (how & AUTOFS_EXP_FORCED)
+ return dentry;
+
/* Can we expire this guy */
if (autofs_can_expire(dentry, timeout, how))
return dentry;
@@ -372,6 +399,11 @@ static struct dentry *should_expire(struct dentry *dentry,
if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
pr_debug("checking symlink %p %pd\n", dentry, dentry);
+
+ /* Forced expire, user space handles busy mounts */
+ if (how & AUTOFS_EXP_FORCED)
+ return dentry;
+
/*
* A symlink can't be "busy" in the usual sense so
* just check last used for expire timeout.
@@ -386,10 +418,13 @@ static struct dentry *should_expire(struct dentry *dentry,
/* Case 2: tree mount, expire iff entire tree is not busy */
if (!(how & AUTOFS_EXP_LEAVES)) {
- /* Path walk currently on this dentry? */
- ino_count = atomic_read(&ino->count) + 1;
- if (d_count(dentry) > ino_count)
- return NULL;
+ /* Not a forced expire? */
+ if (!(how & AUTOFS_EXP_FORCED)) {
+ /* ref-walk currently on this dentry? */
+ ino_count = atomic_read(&ino->count) + 1;
+ if (d_count(dentry) > ino_count)
+ return NULL;
+ }
if (!autofs_tree_busy(mnt, dentry, timeout, how))
return dentry;
@@ -398,12 +433,15 @@ static struct dentry *should_expire(struct dentry *dentry,
* (autofs-4.1).
*/
} else {
- /* Path walk currently on this dentry? */
struct dentry *expired;
- ino_count = atomic_read(&ino->count) + 1;
- if (d_count(dentry) > ino_count)
- return NULL;
+ /* Not a forced expire? */
+ if (!(how & AUTOFS_EXP_FORCED)) {
+ /* ref-walk currently on this dentry? */
+ ino_count = atomic_read(&ino->count) + 1;
+ if (d_count(dentry) > ino_count)
+ return NULL;
+ }
expired = autofs_check_leaves(mnt, dentry, timeout, how);
if (expired) {