Commit 7b06a826 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: use empty snap context for uninline_data and get_pool_perm 



Cached_context in ceph_snap_realm is directly accessed by
uninline_data() and get_pool_perm(). This is racy in theory.
both uninline_data() and get_pool_perm() do not modify existing
object, they only create new object. So we can pass the empty
snap context to them.  Unlike cached_context in ceph_snap_realm,
we do not need to protect the empty snap context.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent b01da6a0

fs/ceph/addr.c

+4 −5
Original line number Diff line number Diff line
@@ -1510,8 +1510,7 @@ int ceph_uninline_data(struct file *filp, struct page *locked_page) 
				    ceph_vino(inode), 0, &len, 0, 1,

				    CEPH_OSD_OP_CREATE,

				    CEPH_OSD_FLAG_ONDISK | CEPH_OSD_FLAG_WRITE,

				    ci->i_snap_realm->cached_context,

				    0, 0, false);

				    ceph_empty_snapc, 0, 0, false);

	if (IS_ERR(req)) {

		err = PTR_ERR(req);

		goto out;
@@ -1529,7 +1528,7 @@ int ceph_uninline_data(struct file *filp, struct page *locked_page) 
				    ceph_vino(inode), 0, &len, 1, 3,

				    CEPH_OSD_OP_WRITE,

				    CEPH_OSD_FLAG_ONDISK | CEPH_OSD_FLAG_WRITE,

				    ci->i_snap_realm->cached_context,

				    ceph_empty_snapc,

				    ci->i_truncate_seq, ci->i_truncate_size,

				    false);

	if (IS_ERR(req)) {
@@ -1653,7 +1652,7 @@ static int __ceph_pool_perm_get(struct ceph_inode_info *ci, u32 pool) 
	}



	rd_req = ceph_osdc_alloc_request(&fsc->client->osdc,

					 ci->i_snap_realm->cached_context,

					 ceph_empty_snapc,

					 1, false, GFP_NOFS);

	if (!rd_req) {

		err = -ENOMEM;
@@ -1668,7 +1667,7 @@ static int __ceph_pool_perm_get(struct ceph_inode_info *ci, u32 pool) 
	rd_req->r_base_oid.name_len = strlen(rd_req->r_base_oid.name);



	wr_req = ceph_osdc_alloc_request(&fsc->client->osdc,

					 ci->i_snap_realm->cached_context,

					 ceph_empty_snapc,

					 1, false, GFP_NOFS);

	if (!wr_req) {

		err = -ENOMEM;

fs/ceph/snap.c

+9 −9
Original line number Diff line number Diff line
@@ -296,7 +296,7 @@ static int cmpu64_rev(const void *a, const void *b) 
}





static struct ceph_snap_context *empty_snapc;

struct ceph_snap_context *ceph_empty_snapc;



/*

 * build the snap context for a given realm.
@@ -338,9 +338,9 @@ static int build_snap_context(struct ceph_snap_realm *realm) 
		return 0;

	}



	if (num == 0 && realm->seq == empty_snapc->seq) {

		ceph_get_snap_context(empty_snapc);

		snapc = empty_snapc;

	if (num == 0 && realm->seq == ceph_empty_snapc->seq) {

		ceph_get_snap_context(ceph_empty_snapc);

		snapc = ceph_empty_snapc;

		goto done;

	}
@@ -482,7 +482,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci) 
		   cap_snap.  lucky us. */

		dout("queue_cap_snap %p already pending\n", inode);

		kfree(capsnap);

	} else if (ci->i_snap_realm->cached_context == empty_snapc) {

	} else if (ci->i_snap_realm->cached_context == ceph_empty_snapc) {

		dout("queue_cap_snap %p empty snapc\n", inode);

		kfree(capsnap);

	} else if (dirty & (CEPH_CAP_AUTH_EXCL|CEPH_CAP_XATTR_EXCL|
@@ -964,14 +964,14 @@ out: 


int __init ceph_snap_init(void)

{

	empty_snapc = ceph_create_snap_context(0, GFP_NOFS);

	if (!empty_snapc)

	ceph_empty_snapc = ceph_create_snap_context(0, GFP_NOFS);

	if (!ceph_empty_snapc)

		return -ENOMEM;

	empty_snapc->seq = 1;

	ceph_empty_snapc->seq = 1;

	return 0;

}



void ceph_snap_exit(void)

{

	ceph_put_snap_context(empty_snapc);

	ceph_put_snap_context(ceph_empty_snapc);

}

fs/ceph/super.h

+1 −0
Original line number Diff line number Diff line
@@ -692,6 +692,7 @@ static inline int default_congestion_kb(void) 




/* snap.c */

extern struct ceph_snap_context *ceph_empty_snapc;

struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,

					       u64 ino);

extern void ceph_get_snap_realm(struct ceph_mds_client *mdsc,

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