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afs: Make vnode->cb_interest RCU safe

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Use RCU-based freeing for afs_cb_interest struct objects and use RCU on
vnode->cb_interest.  Use that change to allow afs_check_validity() to use
read_seqbegin_or_lock() instead of read_seqlock_excl().

This also requires the caller of afs_check_validity() to hold the RCU read
lock across the call.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
2019-05-13 16:14:32 +01:00
parent c925bd0ac4
commit f642404a04
7 changed files with 99 additions and 58 deletions
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12
fs/afs/internal.h
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@@ -554,7 +554,10 @@ struct afs_server {
struct afs_vol_interest {
struct hlist_node srv_link; /* Link in server->cb_volumes */
struct hlist_head cb_interests; /* List of callback interests on the server */
afs_volid_t vid; /* Volume ID to match */
union {
struct rcu_head rcu;
afs_volid_t vid; /* Volume ID to match */
};
unsigned int usage;
};
@@ -566,7 +569,10 @@ struct afs_cb_interest {
struct afs_vol_interest *vol_interest;
struct afs_server *server; /* Server on which this interest resides */
struct super_block *sb; /* Superblock on which inodes reside */
afs_volid_t vid; /* Volume ID to match */
union {
struct rcu_head rcu;
afs_volid_t vid; /* Volume ID to match */
};
refcount_t usage;
};
@@ -676,7 +682,7 @@ struct afs_vnode {
afs_lock_type_t lock_type : 8;
/* outstanding callback notification on this file */
struct afs_cb_interest *cb_interest; /* Server on which this resides */
struct afs_cb_interest __rcu *cb_interest; /* Server on which this resides */
unsigned int cb_s_break; /* Mass break counter on ->server */
unsigned int cb_v_break; /* Mass break counter on ->volume */
unsigned int cb_break; /* Break counter on vnode */