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orangefs: fix orangefs_superblock locking 

* switch orangefs_remount() to taking ORANGEFS_SB(sb) instead of sb
* remove from the list _before_ orangefs_unmount() - request_mutex
in the latter will make sure that nothing observed in the loop in
ORANGEFS_DEV_REMOUNT_ALL handling will get freed until the end
of loop
* on removal, keep the forward pointer and zero the back one.  That
way we can drop and regain the spinlock in the loop body (again,
ORANGEFS_DEV_REMOUNT_ALL one) and still be able to get to the
rest of the list.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
This commit is contained in:
Al Viro 2016-03-25 19:56:34 -04:00 committed by Mike Marshall
parent 6d4c1a30b3
commit 45996492e5
3 changed files with 48 additions and 59 deletions
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43
fs/orangefs/devorangefs-req.c
View File

@ -572,8 +572,7 @@ static long dispatch_ioctl_command(unsigned int command, unsigned long arg)
struct dev_mask_info_s mask_info = { 0 };
struct dev_mask2_info_s mask2_info = { 0, 0 };
int upstream_kmod = 1;
struct list_head *tmp = NULL;
struct orangefs_sb_info_s *orangefs_sb = NULL;
struct orangefs_sb_info_s *orangefs_sb;
/* mtmoore: add locking here */
@ -619,26 +618,32 @@ static long dispatch_ioctl_command(unsigned int command, unsigned long arg)
gossip_debug(GOSSIP_DEV_DEBUG,
"%s: priority remount in progress\n",
__func__);
list_for_each(tmp, &orangefs_superblocks) {
orangefs_sb =
list_entry(tmp,
struct orangefs_sb_info_s,
list);
if (orangefs_sb && (orangefs_sb->sb)) {
gossip_debug(GOSSIP_DEV_DEBUG,
"%s: Remounting SB %p\n",
__func__,
orangefs_sb);
spin_lock(&orangefs_superblocks_lock);
list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
/*
* We have to drop the spinlock, so entries can be
* removed. They can't be freed, though, so we just
* keep the forward pointers and zero the back ones -
* that way we can get to the rest of the list.
*/
if (!orangefs_sb->list.prev)
continue;
gossip_debug(GOSSIP_DEV_DEBUG,
"%s: Remounting SB %p\n",
__func__,
orangefs_sb);
ret = orangefs_remount(orangefs_sb->sb);
if (ret) {
gossip_debug(GOSSIP_DEV_DEBUG,
"SB %p remount failed\n",
orangefs_sb);
break;
}
spin_unlock(&orangefs_superblocks_lock);
ret = orangefs_remount(orangefs_sb);
spin_lock(&orangefs_superblocks_lock);
if (ret) {
gossip_debug(GOSSIP_DEV_DEBUG,
"SB %p remount failed\n",
orangefs_sb);
break;
}
}
spin_unlock(&orangefs_superblocks_lock);
gossip_debug(GOSSIP_DEV_DEBUG,
"%s: priority remount complete\n",
__func__);

34
fs/orangefs/orangefs-kernel.h
View File

@ -462,7 +462,7 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
void *data);
void orangefs_kill_sb(struct super_block *sb);
int orangefs_remount(struct super_block *sb);
int orangefs_remount(struct orangefs_sb_info_s *);
int fsid_key_table_initialize(void);
void fsid_key_table_finalize(void);
@ -598,38 +598,6 @@ int service_operation(struct orangefs_kernel_op_s *op,
((ORANGEFS_SB(inode->i_sb)->flags & ORANGEFS_OPT_INTR) ? \
ORANGEFS_OP_INTERRUPTIBLE : 0)
#define add_orangefs_sb(sb) \
do { \
gossip_debug(GOSSIP_SUPER_DEBUG, \
"Adding SB %p to orangefs superblocks\n", \
ORANGEFS_SB(sb)); \
spin_lock(&orangefs_superblocks_lock); \
list_add_tail(&ORANGEFS_SB(sb)->list, &orangefs_superblocks); \
spin_unlock(&orangefs_superblocks_lock); \
} while (0)
#define remove_orangefs_sb(sb) \
do { \
struct list_head *tmp = NULL; \
struct list_head *tmp_safe = NULL; \
struct orangefs_sb_info_s *orangefs_sb = NULL; \
\
spin_lock(&orangefs_superblocks_lock); \
list_for_each_safe(tmp, tmp_safe, &orangefs_superblocks) { \
orangefs_sb = list_entry(tmp, \
struct orangefs_sb_info_s, \
list); \
if (orangefs_sb && (orangefs_sb->sb == sb)) { \
gossip_debug(GOSSIP_SUPER_DEBUG, \
"Removing SB %p from orangefs superblocks\n", \
orangefs_sb); \
list_del(&orangefs_sb->list); \
break; \
} \
} \
spin_unlock(&orangefs_superblocks_lock); \
} while (0)
#define fill_default_sys_attrs(sys_attr, type, mode) \
do { \
sys_attr.owner = from_kuid(current_user_ns(), current_fsuid()); \

30
fs/orangefs/super.c
View File

@ -210,7 +210,7 @@ static int orangefs_remount_fs(struct super_block *sb, int *flags, char *data)
* the client regains all of the mount information from us.
* NOTE: this function assumes that the request_mutex is already acquired!
*/
int orangefs_remount(struct super_block *sb)
int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
{
struct orangefs_kernel_op_s *new_op;
int ret = -EINVAL;
@ -221,7 +221,7 @@ int orangefs_remount(struct super_block *sb)
if (!new_op)
return -ENOMEM;
strncpy(new_op->upcall.req.fs_mount.orangefs_config_server,
ORANGEFS_SB(sb)->devname,
orangefs_sb->devname,
ORANGEFS_MAX_SERVER_ADDR_LEN);
gossip_debug(GOSSIP_SUPER_DEBUG,
@ -244,8 +244,8 @@ int orangefs_remount(struct super_block *sb)
* short-lived mapping that the system interface uses
* to map this superblock to a particular mount entry
*/
ORANGEFS_SB(sb)->id = new_op->downcall.resp.fs_mount.id;
ORANGEFS_SB(sb)->mount_pending = 0;
orangefs_sb->id = new_op->downcall.resp.fs_mount.id;
orangefs_sb->mount_pending = 0;
}
op_release(new_op);
@ -485,7 +485,12 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
* finally, add this sb to our list of known orangefs
* sb's
*/
add_orangefs_sb(sb);
gossip_debug(GOSSIP_SUPER_DEBUG,
"Adding SB %p to orangefs superblocks\n",
ORANGEFS_SB(sb));
spin_lock(&orangefs_superblocks_lock);
list_add_tail(&ORANGEFS_SB(sb)->list, &orangefs_superblocks);
spin_unlock(&orangefs_superblocks_lock);
op_release(new_op);
return dget(sb->s_root);
@ -512,10 +517,21 @@ void orangefs_kill_sb(struct super_block *sb)
* issue the unmount to userspace to tell it to remove the
* dynamic mount info it has for this superblock
*/
orangefs_unmount_sb(sb);
orangefs_unmount_sb(sb);
/* remove the sb from our list of orangefs specific sb's */
remove_orangefs_sb(sb);
spin_lock(&orangefs_superblocks_lock);
__list_del_entry(&ORANGEFS_SB(sb)->list); /* not list_del_init */
ORANGEFS_SB(sb)->list.prev = NULL;
spin_unlock(&orangefs_superblocks_lock);
/*
* make sure that ORANGEFS_DEV_REMOUNT_ALL loop that might've seen us
* gets completed before we free the dang thing.
*/
mutex_lock(&request_mutex);
mutex_unlock(&request_mutex);
/* free the orangefs superblock private data */
kfree(ORANGEFS_SB(sb));