From b647c35f77af9c07d336247b23014596e9f0a593 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 28 Oct 2010 11:16:44 -0400 Subject: [PATCH] cifs: convert tlink_tree to a rbtree Radix trees are ideal when you want to track a bunch of pointers and can't embed a tracking structure within the target of those pointers. The tradeoff is an increase in memory, particularly if the tree is sparse. In CIFS, we use the tlink_tree to track tcon_link structs. A tcon_link can never be in more than one tlink_tree, so there's no impediment to using a rb_tree here instead of a radix tree. Convert the new multiuser mount code to use a rb_tree instead. This should reduce the memory required to manage the tlink_tree. Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/cifs_fs_sb.h | 4 +- fs/cifs/cifsfs.c | 2 +- fs/cifs/cifsglob.h | 3 +- fs/cifs/connect.c | 177 +++++++++++++++++++++++-------------------- 4 files changed, 101 insertions(+), 85 deletions(-) diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h index 79576dac336f..e9a393c9c2ca 100644 --- a/fs/cifs/cifs_fs_sb.h +++ b/fs/cifs/cifs_fs_sb.h @@ -15,7 +15,7 @@ * the GNU Lesser General Public License for more details. * */ -#include +#include #ifndef _CIFS_FS_SB_H #define _CIFS_FS_SB_H @@ -42,7 +42,7 @@ #define CIFS_MOUNT_MULTIUSER 0x20000 /* multiuser mount */ struct cifs_sb_info { - struct radix_tree_root tlink_tree; + struct rb_root tlink_tree; spinlock_t tlink_tree_lock; struct tcon_link *master_tlink; struct nls_table *local_nls; diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 75c4eaa79588..38526a6c4acf 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -116,7 +116,7 @@ cifs_read_super(struct super_block *sb, void *data, return -ENOMEM; spin_lock_init(&cifs_sb->tlink_tree_lock); - INIT_RADIX_TREE(&cifs_sb->tlink_tree, GFP_KERNEL); + cifs_sb->tlink_tree = RB_ROOT; rc = bdi_setup_and_register(&cifs_sb->bdi, "cifs", BDI_CAP_MAP_COPY); if (rc) { diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index f259e4d7612d..b577bf0a1bb3 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -336,7 +336,8 @@ struct cifsTconInfo { * "get" on the container. */ struct tcon_link { - unsigned long tl_index; + struct rb_node tl_rbnode; + uid_t tl_uid; unsigned long tl_flags; #define TCON_LINK_MASTER 0 #define TCON_LINK_PENDING 1 diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 197ac579a70b..c9699ce767b6 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -116,6 +116,7 @@ struct smb_vol { static int ipv4_connect(struct TCP_Server_Info *server); static int ipv6_connect(struct TCP_Server_Info *server); +static void tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink); static void cifs_prune_tlinks(struct work_struct *work); /* @@ -2900,24 +2901,16 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, goto mount_fail_check; } - tlink->tl_index = pSesInfo->linux_uid; + tlink->tl_uid = pSesInfo->linux_uid; tlink->tl_tcon = tcon; tlink->tl_time = jiffies; set_bit(TCON_LINK_MASTER, &tlink->tl_flags); set_bit(TCON_LINK_IN_TREE, &tlink->tl_flags); - rc = radix_tree_preload(GFP_KERNEL); - if (rc == -ENOMEM) { - kfree(tlink); - goto mount_fail_check; - } - + cifs_sb->master_tlink = tlink; spin_lock(&cifs_sb->tlink_tree_lock); - radix_tree_insert(&cifs_sb->tlink_tree, pSesInfo->linux_uid, tlink); + tlink_rb_insert(&cifs_sb->tlink_tree, tlink); spin_unlock(&cifs_sb->tlink_tree_lock); - radix_tree_preload_end(); - - cifs_sb->master_tlink = tlink; queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks, TLINK_IDLE_EXPIRE); @@ -3107,32 +3100,25 @@ CIFSTCon(unsigned int xid, struct cifsSesInfo *ses, int cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb) { - int i, ret; + struct rb_root *root = &cifs_sb->tlink_tree; + struct rb_node *node; + struct tcon_link *tlink; char *tmp; - struct tcon_link *tlink[8]; - unsigned long index = 0; cancel_delayed_work_sync(&cifs_sb->prune_tlinks); - do { - spin_lock(&cifs_sb->tlink_tree_lock); - ret = radix_tree_gang_lookup(&cifs_sb->tlink_tree, - (void **)tlink, index, - ARRAY_SIZE(tlink)); - /* increment index for next pass */ - if (ret > 0) - index = tlink[ret - 1]->tl_index + 1; - for (i = 0; i < ret; i++) { - cifs_get_tlink(tlink[i]); - clear_bit(TCON_LINK_IN_TREE, &tlink[i]->tl_flags); - radix_tree_delete(&cifs_sb->tlink_tree, - tlink[i]->tl_index); - } - spin_unlock(&cifs_sb->tlink_tree_lock); + spin_lock(&cifs_sb->tlink_tree_lock); + while ((node = rb_first(root))) { + tlink = rb_entry(node, struct tcon_link, tl_rbnode); + cifs_get_tlink(tlink); + clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags); + rb_erase(node, root); - for (i = 0; i < ret; i++) - cifs_put_tlink(tlink[i]); - } while (ret != 0); + spin_unlock(&cifs_sb->tlink_tree_lock); + cifs_put_tlink(tlink); + spin_lock(&cifs_sb->tlink_tree_lock); + } + spin_unlock(&cifs_sb->tlink_tree_lock); tmp = cifs_sb->prepath; cifs_sb->prepathlen = 0; @@ -3290,6 +3276,47 @@ cifs_sb_tcon_pending_wait(void *unused) return signal_pending(current) ? -ERESTARTSYS : 0; } +/* find and return a tlink with given uid */ +static struct tcon_link * +tlink_rb_search(struct rb_root *root, uid_t uid) +{ + struct rb_node *node = root->rb_node; + struct tcon_link *tlink; + + while (node) { + tlink = rb_entry(node, struct tcon_link, tl_rbnode); + + if (tlink->tl_uid > uid) + node = node->rb_left; + else if (tlink->tl_uid < uid) + node = node->rb_right; + else + return tlink; + } + return NULL; +} + +/* insert a tcon_link into the tree */ +static void +tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink) +{ + struct rb_node **new = &(root->rb_node), *parent = NULL; + struct tcon_link *tlink; + + while (*new) { + tlink = rb_entry(*new, struct tcon_link, tl_rbnode); + parent = *new; + + if (tlink->tl_uid > new_tlink->tl_uid) + new = &((*new)->rb_left); + else + new = &((*new)->rb_right); + } + + rb_link_node(&new_tlink->tl_rbnode, parent, new); + rb_insert_color(&new_tlink->tl_rbnode, root); +} + /* * Find or construct an appropriate tcon given a cifs_sb and the fsuid of the * current task. @@ -3310,14 +3337,14 @@ struct tcon_link * cifs_sb_tlink(struct cifs_sb_info *cifs_sb) { int ret; - unsigned long fsuid = (unsigned long) current_fsuid(); + uid_t fsuid = current_fsuid(); struct tcon_link *tlink, *newtlink; if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER)) return cifs_get_tlink(cifs_sb_master_tlink(cifs_sb)); spin_lock(&cifs_sb->tlink_tree_lock); - tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid); + tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid); if (tlink) cifs_get_tlink(tlink); spin_unlock(&cifs_sb->tlink_tree_lock); @@ -3326,36 +3353,24 @@ cifs_sb_tlink(struct cifs_sb_info *cifs_sb) newtlink = kzalloc(sizeof(*tlink), GFP_KERNEL); if (newtlink == NULL) return ERR_PTR(-ENOMEM); - newtlink->tl_index = fsuid; + newtlink->tl_uid = fsuid; newtlink->tl_tcon = ERR_PTR(-EACCES); set_bit(TCON_LINK_PENDING, &newtlink->tl_flags); set_bit(TCON_LINK_IN_TREE, &newtlink->tl_flags); cifs_get_tlink(newtlink); - ret = radix_tree_preload(GFP_KERNEL); - if (ret != 0) { - kfree(newtlink); - return ERR_PTR(ret); - } - spin_lock(&cifs_sb->tlink_tree_lock); /* was one inserted after previous search? */ - tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid); + tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid); if (tlink) { cifs_get_tlink(tlink); spin_unlock(&cifs_sb->tlink_tree_lock); - radix_tree_preload_end(); kfree(newtlink); goto wait_for_construction; } - ret = radix_tree_insert(&cifs_sb->tlink_tree, fsuid, newtlink); - spin_unlock(&cifs_sb->tlink_tree_lock); - radix_tree_preload_end(); - if (ret) { - kfree(newtlink); - return ERR_PTR(ret); - } tlink = newtlink; + tlink_rb_insert(&cifs_sb->tlink_tree, tlink); + spin_unlock(&cifs_sb->tlink_tree_lock); } else { wait_for_construction: ret = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING, @@ -3401,39 +3416,39 @@ cifs_prune_tlinks(struct work_struct *work) { struct cifs_sb_info *cifs_sb = container_of(work, struct cifs_sb_info, prune_tlinks.work); - struct tcon_link *tlink[8]; - unsigned long now = jiffies; - unsigned long index = 0; - int i, ret; + struct rb_root *root = &cifs_sb->tlink_tree; + struct rb_node *node = rb_first(root); + struct rb_node *tmp; + struct tcon_link *tlink; - do { - spin_lock(&cifs_sb->tlink_tree_lock); - ret = radix_tree_gang_lookup(&cifs_sb->tlink_tree, - (void **)tlink, index, - ARRAY_SIZE(tlink)); - /* increment index for next pass */ - if (ret > 0) - index = tlink[ret - 1]->tl_index + 1; - for (i = 0; i < ret; i++) { - if (test_bit(TCON_LINK_MASTER, &tlink[i]->tl_flags) || - atomic_read(&tlink[i]->tl_count) != 0 || - time_after(tlink[i]->tl_time + TLINK_IDLE_EXPIRE, - now)) { - tlink[i] = NULL; - continue; - } - cifs_get_tlink(tlink[i]); - clear_bit(TCON_LINK_IN_TREE, &tlink[i]->tl_flags); - radix_tree_delete(&cifs_sb->tlink_tree, - tlink[i]->tl_index); - } - spin_unlock(&cifs_sb->tlink_tree_lock); + /* + * Because we drop the spinlock in the loop in order to put the tlink + * it's not guarded against removal of links from the tree. The only + * places that remove entries from the tree are this function and + * umounts. Because this function is non-reentrant and is canceled + * before umount can proceed, this is safe. + */ + spin_lock(&cifs_sb->tlink_tree_lock); + node = rb_first(root); + while (node != NULL) { + tmp = node; + node = rb_next(tmp); + tlink = rb_entry(tmp, struct tcon_link, tl_rbnode); + + if (test_bit(TCON_LINK_MASTER, &tlink->tl_flags) || + atomic_read(&tlink->tl_count) != 0 || + time_after(tlink->tl_time + TLINK_IDLE_EXPIRE, jiffies)) + continue; - for (i = 0; i < ret; i++) { - if (tlink[i] != NULL) - cifs_put_tlink(tlink[i]); - } - } while (ret != 0); + cifs_get_tlink(tlink); + clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags); + rb_erase(tmp, root); + + spin_unlock(&cifs_sb->tlink_tree_lock); + cifs_put_tlink(tlink); + spin_lock(&cifs_sb->tlink_tree_lock); + } + spin_unlock(&cifs_sb->tlink_tree_lock); queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks, TLINK_IDLE_EXPIRE); -- GitLab