From patchwork Mon Jul 22 01:23:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Simmons X-Patchwork-Id: 11051307 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A013D1398 for ; Mon, 22 Jul 2019 01:24:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8495826E4A for ; Mon, 22 Jul 2019 01:24:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 787D5284AA; Mon, 22 Jul 2019 01:24:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from pdx1-mailman02.dreamhost.com (pdx1-mailman02.dreamhost.com [64.90.62.194]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 618ED26E4A for ; Mon, 22 Jul 2019 01:24:34 +0000 (UTC) Received: from pdx1-mailman02.dreamhost.com (localhost [IPv6:::1]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id 7BEA621FD96; Sun, 21 Jul 2019 18:24:21 -0700 (PDT) X-Original-To: lustre-devel@lists.lustre.org Delivered-To: lustre-devel-lustre.org@pdx1-mailman02.dreamhost.com Received: from smtp3.ccs.ornl.gov (smtp3.ccs.ornl.gov [160.91.203.39]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id ED9ED21FD1F for ; Sun, 21 Jul 2019 18:24:01 -0700 (PDT) Received: from star.ccs.ornl.gov (star.ccs.ornl.gov [160.91.202.134]) by smtp3.ccs.ornl.gov (Postfix) with ESMTP id E57DF27E; Sun, 21 Jul 2019 21:23:55 -0400 (EDT) Received: by star.ccs.ornl.gov (Postfix, from userid 2004) id DD4651F3; Sun, 21 Jul 2019 21:23:55 -0400 (EDT) From: James Simmons To: Andreas Dilger , Oleg Drokin , NeilBrown , Shaun Tancheff , Li Dongyang , Artem Blagodarenko , Yang Sheng Date: Sun, 21 Jul 2019 21:23:41 -0400 Message-Id: <1563758631-29550-13-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1563758631-29550-1-git-send-email-jsimmons@infradead.org> References: <1563758631-29550-1-git-send-email-jsimmons@infradead.org> Subject: [lustre-devel] [PATCH 12/22] ext4: add htree lock implementation X-BeenThere: lustre-devel@lists.lustre.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "For discussing Lustre software development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lustre Development List MIME-Version: 1.0 Errors-To: lustre-devel-bounces@lists.lustre.org Sender: "lustre-devel" X-Virus-Scanned: ClamAV using ClamSMTP Used for parallel lookup Signed-off-by: James Simmons --- fs/ext4/Makefile | 4 +- fs/ext4/ext4.h | 80 +++++ fs/ext4/htree_lock.c | 891 +++++++++++++++++++++++++++++++++++++++++++++++++++ fs/ext4/htree_lock.h | 187 +++++++++++ fs/ext4/namei.c | 461 +++++++++++++++++++++++--- fs/ext4/super.c | 1 + 6 files changed, 1583 insertions(+), 41 deletions(-) create mode 100644 fs/ext4/htree_lock.c create mode 100644 fs/ext4/htree_lock.h diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile index 8fdfcd3..0d0a28f 100644 --- a/fs/ext4/Makefile +++ b/fs/ext4/Makefile @@ -6,8 +6,8 @@ obj-$(CONFIG_EXT4_FS) += ext4.o ext4-y := balloc.o bitmap.o block_validity.o dir.o ext4_jbd2.o extents.o \ - extents_status.o file.o fsmap.o fsync.o hash.o ialloc.o \ - indirect.o inline.o inode.o ioctl.o mballoc.o migrate.o \ + extents_status.o file.o fsmap.o fsync.o hash.o htree_lock.o \ + ialloc.o indirect.o inline.o inode.o ioctl.o mballoc.o migrate.o \ mmp.o move_extent.o namei.o page-io.o readpage.o resize.o \ super.o symlink.o sysfs.o xattr.o xattr_trusted.o xattr_user.o diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 80601a9..bf74c7c 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -44,6 +44,8 @@ #include +#include "htree_lock.h" + /* * The fourth extended filesystem constants/structures */ @@ -936,6 +938,9 @@ struct ext4_inode_info { __u32 i_dtime; ext4_fsblk_t i_file_acl; + /* following fields for parallel directory operations -bzzz */ + struct semaphore i_append_sem; + /* * i_block_group is the number of the block group which contains * this file's inode. Constant across the lifetime of the inode, @@ -2145,6 +2150,72 @@ struct dx_hash_info */ #define HASH_NB_ALWAYS 1 +/* assume name-hash is protected by upper layer */ +#define EXT4_HTREE_LOCK_HASH 0 + +enum ext4_pdo_lk_types { +#if EXT4_HTREE_LOCK_HASH + EXT4_LK_HASH, +#endif + EXT4_LK_DX, /* index block */ + EXT4_LK_DE, /* directory entry block */ + EXT4_LK_SPIN, /* spinlock */ + EXT4_LK_MAX, +}; + +/* read-only bit */ +#define EXT4_LB_RO(b) (1 << (b)) +/* read + write, high bits for writer */ +#define EXT4_LB_RW(b) ((1 << (b)) | (1 << (EXT4_LK_MAX + (b)))) + +enum ext4_pdo_lock_bits { + /* DX lock bits */ + EXT4_LB_DX_RO = EXT4_LB_RO(EXT4_LK_DX), + EXT4_LB_DX = EXT4_LB_RW(EXT4_LK_DX), + /* DE lock bits */ + EXT4_LB_DE_RO = EXT4_LB_RO(EXT4_LK_DE), + EXT4_LB_DE = EXT4_LB_RW(EXT4_LK_DE), + /* DX spinlock bits */ + EXT4_LB_SPIN_RO = EXT4_LB_RO(EXT4_LK_SPIN), + EXT4_LB_SPIN = EXT4_LB_RW(EXT4_LK_SPIN), + /* accurate searching */ + EXT4_LB_EXACT = EXT4_LB_RO(EXT4_LK_MAX << 1), +}; + +enum ext4_pdo_lock_opc { + /* external */ + EXT4_HLOCK_READDIR = (EXT4_LB_DE_RO | EXT4_LB_DX_RO), + EXT4_HLOCK_LOOKUP = (EXT4_LB_DE_RO | EXT4_LB_SPIN_RO | + EXT4_LB_EXACT), + EXT4_HLOCK_DEL = (EXT4_LB_DE | EXT4_LB_SPIN_RO | + EXT4_LB_EXACT), + EXT4_HLOCK_ADD = (EXT4_LB_DE | EXT4_LB_SPIN_RO), + + /* internal */ + EXT4_HLOCK_LOOKUP_SAFE = (EXT4_LB_DE_RO | EXT4_LB_DX_RO | + EXT4_LB_EXACT), + EXT4_HLOCK_DEL_SAFE = (EXT4_LB_DE | EXT4_LB_DX_RO | EXT4_LB_EXACT), + EXT4_HLOCK_SPLIT = (EXT4_LB_DE | EXT4_LB_DX | EXT4_LB_SPIN), +}; + +extern struct htree_lock_head *ext4_htree_lock_head_alloc(unsigned hbits); +#define ext4_htree_lock_head_free(lhead) htree_lock_head_free(lhead) + +extern struct htree_lock *ext4_htree_lock_alloc(void); +#define ext4_htree_lock_free(lck) htree_lock_free(lck) + +extern void ext4_htree_lock(struct htree_lock *lck, + struct htree_lock_head *lhead, + struct inode *dir, unsigned flags); +#define ext4_htree_unlock(lck) htree_unlock(lck) + +extern struct buffer_head *ext4_find_entry_locked(struct inode *dir, + const struct qstr *d_name, + struct ext4_dir_entry_2 **res_dir, + int *inlined, struct htree_lock *lck); +extern int ext4_add_entry_locked(handle_t *handle, struct dentry *dentry, + struct inode *inode, struct htree_lock *lck); + struct ext4_filename { const struct qstr *usr_fname; struct fscrypt_str disk_name; @@ -2479,8 +2550,17 @@ void ext4_insert_dentry(struct inode *inode, struct ext4_filename *fname, void *data); static inline void ext4_update_dx_flag(struct inode *inode) { + /* Disable it for ldiskfs, because going from a DX directory to + * a non-DX directory while it is in use will completely break + * the htree-locking. + * If we really want to support this operation in the future, + * we need to exclusively lock the directory at here which will + * increase complexity of code + */ +#if 0 if (!ext4_has_feature_dir_index(inode->i_sb)) ext4_clear_inode_flag(inode, EXT4_INODE_INDEX); +#endif } static const unsigned char ext4_filetype_table[] = { DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK diff --git a/fs/ext4/htree_lock.c b/fs/ext4/htree_lock.c new file mode 100644 index 0000000..9c1e8f0 --- /dev/null +++ b/fs/ext4/htree_lock.c @@ -0,0 +1,891 @@ +/* + * fs/ext4/htree_lock.c + * + * Copyright (c) 2011, 2012, Intel Corporation. + * + * Author: Liang Zhen + */ +#include +#include +#include +#include "htree_lock.h" + +enum { + HTREE_LOCK_BIT_EX = (1 << HTREE_LOCK_EX), + HTREE_LOCK_BIT_PW = (1 << HTREE_LOCK_PW), + HTREE_LOCK_BIT_PR = (1 << HTREE_LOCK_PR), + HTREE_LOCK_BIT_CW = (1 << HTREE_LOCK_CW), + HTREE_LOCK_BIT_CR = (1 << HTREE_LOCK_CR), +}; + +enum { + HTREE_LOCK_COMPAT_EX = 0, + HTREE_LOCK_COMPAT_PW = HTREE_LOCK_COMPAT_EX | HTREE_LOCK_BIT_CR, + HTREE_LOCK_COMPAT_PR = HTREE_LOCK_COMPAT_PW | HTREE_LOCK_BIT_PR, + HTREE_LOCK_COMPAT_CW = HTREE_LOCK_COMPAT_PW | HTREE_LOCK_BIT_CW, + HTREE_LOCK_COMPAT_CR = HTREE_LOCK_COMPAT_CW | HTREE_LOCK_BIT_PR | + HTREE_LOCK_BIT_PW, +}; + +static int htree_lock_compat[] = { + [HTREE_LOCK_EX] HTREE_LOCK_COMPAT_EX, + [HTREE_LOCK_PW] HTREE_LOCK_COMPAT_PW, + [HTREE_LOCK_PR] HTREE_LOCK_COMPAT_PR, + [HTREE_LOCK_CW] HTREE_LOCK_COMPAT_CW, + [HTREE_LOCK_CR] HTREE_LOCK_COMPAT_CR, +}; + +/* max allowed htree-lock depth. + * We only need depth=3 for ext4 although user can have higher value. */ +#define HTREE_LOCK_DEP_MAX 16 + +#ifdef HTREE_LOCK_DEBUG + +static char *hl_name[] = { + [HTREE_LOCK_EX] "EX", + [HTREE_LOCK_PW] "PW", + [HTREE_LOCK_PR] "PR", + [HTREE_LOCK_CW] "CW", + [HTREE_LOCK_CR] "CR", +}; + +/* lock stats */ +struct htree_lock_node_stats { + unsigned long long blocked[HTREE_LOCK_MAX]; + unsigned long long granted[HTREE_LOCK_MAX]; + unsigned long long retried[HTREE_LOCK_MAX]; + unsigned long long events; +}; + +struct htree_lock_stats { + struct htree_lock_node_stats nodes[HTREE_LOCK_DEP_MAX]; + unsigned long long granted[HTREE_LOCK_MAX]; + unsigned long long blocked[HTREE_LOCK_MAX]; +}; + +static struct htree_lock_stats hl_stats; + +void htree_lock_stat_reset(void) +{ + memset(&hl_stats, 0, sizeof(hl_stats)); +} + +void htree_lock_stat_print(int depth) +{ + int i; + int j; + + printk(KERN_DEBUG "HTREE LOCK STATS:\n"); + for (i = 0; i < HTREE_LOCK_MAX; i++) { + printk(KERN_DEBUG "[%s]: G [%10llu], B [%10llu]\n", + hl_name[i], hl_stats.granted[i], hl_stats.blocked[i]); + } + for (i = 0; i < depth; i++) { + printk(KERN_DEBUG "HTREE CHILD [%d] STATS:\n", i); + for (j = 0; j < HTREE_LOCK_MAX; j++) { + printk(KERN_DEBUG + "[%s]: G [%10llu], B [%10llu], R [%10llu]\n", + hl_name[j], hl_stats.nodes[i].granted[j], + hl_stats.nodes[i].blocked[j], + hl_stats.nodes[i].retried[j]); + } + } +} + +#define lk_grant_inc(m) do { hl_stats.granted[m]++; } while (0) +#define lk_block_inc(m) do { hl_stats.blocked[m]++; } while (0) +#define ln_grant_inc(d, m) do { hl_stats.nodes[d].granted[m]++; } while (0) +#define ln_block_inc(d, m) do { hl_stats.nodes[d].blocked[m]++; } while (0) +#define ln_retry_inc(d, m) do { hl_stats.nodes[d].retried[m]++; } while (0) +#define ln_event_inc(d) do { hl_stats.nodes[d].events++; } while (0) + +#else /* !DEBUG */ + +void htree_lock_stat_reset(void) {} +void htree_lock_stat_print(int depth) {} + +#define lk_grant_inc(m) do {} while (0) +#define lk_block_inc(m) do {} while (0) +#define ln_grant_inc(d, m) do {} while (0) +#define ln_block_inc(d, m) do {} while (0) +#define ln_retry_inc(d, m) do {} while (0) +#define ln_event_inc(d) do {} while (0) + +#endif /* DEBUG */ + +EXPORT_SYMBOL(htree_lock_stat_reset); +EXPORT_SYMBOL(htree_lock_stat_print); + +#define HTREE_DEP_ROOT (-1) + +#define htree_spin_lock(lhead, dep) \ + bit_spin_lock((dep) + 1, &(lhead)->lh_lock) +#define htree_spin_unlock(lhead, dep) \ + bit_spin_unlock((dep) + 1, &(lhead)->lh_lock) + +#define htree_key_event_ignore(child, ln) \ + (!((child)->lc_events & (1 << (ln)->ln_mode))) + +static int +htree_key_list_empty(struct htree_lock_node *ln) +{ + return list_empty(&ln->ln_major_list) && list_empty(&ln->ln_minor_list); +} + +static void +htree_key_list_del_init(struct htree_lock_node *ln) +{ + struct htree_lock_node *tmp = NULL; + + if (!list_empty(&ln->ln_minor_list)) { + tmp = list_entry(ln->ln_minor_list.next, + struct htree_lock_node, ln_minor_list); + list_del_init(&ln->ln_minor_list); + } + + if (list_empty(&ln->ln_major_list)) + return; + + if (tmp == NULL) { /* not on minor key list */ + list_del_init(&ln->ln_major_list); + } else { + BUG_ON(!list_empty(&tmp->ln_major_list)); + list_replace_init(&ln->ln_major_list, &tmp->ln_major_list); + } +} + +static void +htree_key_list_replace_init(struct htree_lock_node *old, + struct htree_lock_node *new) +{ + if (!list_empty(&old->ln_major_list)) + list_replace_init(&old->ln_major_list, &new->ln_major_list); + + if (!list_empty(&old->ln_minor_list)) + list_replace_init(&old->ln_minor_list, &new->ln_minor_list); +} + +static void +htree_key_event_enqueue(struct htree_lock_child *child, + struct htree_lock_node *ln, int dep, void *event) +{ + struct htree_lock_node *tmp; + + /* NB: ALWAYS called holding lhead::lh_lock(dep) */ + BUG_ON(ln->ln_mode == HTREE_LOCK_NL); + if (event == NULL || htree_key_event_ignore(child, ln)) + return; + + /* shouldn't be a very long list */ + list_for_each_entry(tmp, &ln->ln_alive_list, ln_alive_list) { + if (tmp->ln_mode == HTREE_LOCK_NL) { + ln_event_inc(dep); + if (child->lc_callback != NULL) + child->lc_callback(tmp->ln_ev_target, event); + } + } +} + +static int +htree_node_lock_enqueue(struct htree_lock *newlk, struct htree_lock *curlk, + unsigned dep, int wait, void *event) +{ + struct htree_lock_child *child = &newlk->lk_head->lh_children[dep]; + struct htree_lock_node *newln = &newlk->lk_nodes[dep]; + struct htree_lock_node *curln = &curlk->lk_nodes[dep]; + + /* NB: ALWAYS called holding lhead::lh_lock(dep) */ + /* NB: we only expect PR/PW lock mode at here, only these two modes are + * allowed for htree_node_lock(asserted in htree_node_lock_internal), + * NL is only used for listener, user can't directly require NL mode */ + if ((curln->ln_mode == HTREE_LOCK_NL) || + (curln->ln_mode != HTREE_LOCK_PW && + newln->ln_mode != HTREE_LOCK_PW)) { + /* no conflict, attach it on granted list of @curlk */ + if (curln->ln_mode != HTREE_LOCK_NL) { + list_add(&newln->ln_granted_list, + &curln->ln_granted_list); + } else { + /* replace key owner */ + htree_key_list_replace_init(curln, newln); + } + + list_add(&newln->ln_alive_list, &curln->ln_alive_list); + htree_key_event_enqueue(child, newln, dep, event); + ln_grant_inc(dep, newln->ln_mode); + return 1; /* still hold lh_lock */ + } + + if (!wait) { /* can't grant and don't want to wait */ + ln_retry_inc(dep, newln->ln_mode); + newln->ln_mode = HTREE_LOCK_INVAL; + return -1; /* don't wait and just return -1 */ + } + + newlk->lk_task = current; + set_current_state(TASK_UNINTERRUPTIBLE); + /* conflict, attach it on blocked list of curlk */ + list_add_tail(&newln->ln_blocked_list, &curln->ln_blocked_list); + list_add(&newln->ln_alive_list, &curln->ln_alive_list); + ln_block_inc(dep, newln->ln_mode); + + htree_spin_unlock(newlk->lk_head, dep); + /* wait to be given the lock */ + if (newlk->lk_task != NULL) + schedule(); + /* granted, no doubt, wake up will set me RUNNING */ + if (event == NULL || htree_key_event_ignore(child, newln)) + return 0; /* granted without lh_lock */ + + htree_spin_lock(newlk->lk_head, dep); + htree_key_event_enqueue(child, newln, dep, event); + return 1; /* still hold lh_lock */ +} + +/* + * get PR/PW access to particular tree-node according to @dep and @key, + * it will return -1 if @wait is false and can't immediately grant this lock. + * All listeners(HTREE_LOCK_NL) on @dep and with the same @key will get + * @event if it's not NULL. + * NB: ALWAYS called holding lhead::lh_lock + */ +static int +htree_node_lock_internal(struct htree_lock_head *lhead, struct htree_lock *lck, + htree_lock_mode_t mode, u32 key, unsigned dep, + int wait, void *event) +{ + LIST_HEAD(list); + struct htree_lock *tmp; + struct htree_lock *tmp2; + u16 major; + u16 minor; + u8 reverse; + u8 ma_bits; + u8 mi_bits; + + BUG_ON(mode != HTREE_LOCK_PW && mode != HTREE_LOCK_PR); + BUG_ON(htree_node_is_granted(lck, dep)); + + key = hash_long(key, lhead->lh_hbits); + + mi_bits = lhead->lh_hbits >> 1; + ma_bits = lhead->lh_hbits - mi_bits; + + lck->lk_nodes[dep].ln_major_key = major = key & ((1U << ma_bits) - 1); + lck->lk_nodes[dep].ln_minor_key = minor = key >> ma_bits; + lck->lk_nodes[dep].ln_mode = mode; + + /* + * The major key list is an ordered list, so searches are started + * at the end of the list that is numerically closer to major_key, + * so at most half of the list will be walked (for well-distributed + * keys). The list traversal aborts early if the expected key + * location is passed. + */ + reverse = (major >= (1 << (ma_bits - 1))); + + if (reverse) { + list_for_each_entry_reverse(tmp, + &lhead->lh_children[dep].lc_list, + lk_nodes[dep].ln_major_list) { + if (tmp->lk_nodes[dep].ln_major_key == major) { + goto search_minor; + + } else if (tmp->lk_nodes[dep].ln_major_key < major) { + /* attach _after_ @tmp */ + list_add(&lck->lk_nodes[dep].ln_major_list, + &tmp->lk_nodes[dep].ln_major_list); + goto out_grant_major; + } + } + + list_add(&lck->lk_nodes[dep].ln_major_list, + &lhead->lh_children[dep].lc_list); + goto out_grant_major; + + } else { + list_for_each_entry(tmp, &lhead->lh_children[dep].lc_list, + lk_nodes[dep].ln_major_list) { + if (tmp->lk_nodes[dep].ln_major_key == major) { + goto search_minor; + + } else if (tmp->lk_nodes[dep].ln_major_key > major) { + /* insert _before_ @tmp */ + list_add_tail(&lck->lk_nodes[dep].ln_major_list, + &tmp->lk_nodes[dep].ln_major_list); + goto out_grant_major; + } + } + + list_add_tail(&lck->lk_nodes[dep].ln_major_list, + &lhead->lh_children[dep].lc_list); + goto out_grant_major; + } + + search_minor: + /* + * NB: minor_key list doesn't have a "head", @list is just a + * temporary stub for helping list searching, make sure it's removed + * after searching. + * minor_key list is an ordered list too. + */ + list_add_tail(&list, &tmp->lk_nodes[dep].ln_minor_list); + + reverse = (minor >= (1 << (mi_bits - 1))); + + if (reverse) { + list_for_each_entry_reverse(tmp2, &list, + lk_nodes[dep].ln_minor_list) { + if (tmp2->lk_nodes[dep].ln_minor_key == minor) { + goto out_enqueue; + + } else if (tmp2->lk_nodes[dep].ln_minor_key < minor) { + /* attach _after_ @tmp2 */ + list_add(&lck->lk_nodes[dep].ln_minor_list, + &tmp2->lk_nodes[dep].ln_minor_list); + goto out_grant_minor; + } + } + + list_add(&lck->lk_nodes[dep].ln_minor_list, &list); + + } else { + list_for_each_entry(tmp2, &list, + lk_nodes[dep].ln_minor_list) { + if (tmp2->lk_nodes[dep].ln_minor_key == minor) { + goto out_enqueue; + + } else if (tmp2->lk_nodes[dep].ln_minor_key > minor) { + /* insert _before_ @tmp2 */ + list_add_tail(&lck->lk_nodes[dep].ln_minor_list, + &tmp2->lk_nodes[dep].ln_minor_list); + goto out_grant_minor; + } + } + + list_add_tail(&lck->lk_nodes[dep].ln_minor_list, &list); + } + + out_grant_minor: + if (list.next == &lck->lk_nodes[dep].ln_minor_list) { + /* new lock @lck is the first one on minor_key list, which + * means it has the smallest minor_key and it should + * replace @tmp as minor_key owner */ + list_replace_init(&tmp->lk_nodes[dep].ln_major_list, + &lck->lk_nodes[dep].ln_major_list); + } + /* remove the temporary head */ + list_del(&list); + + out_grant_major: + ln_grant_inc(dep, lck->lk_nodes[dep].ln_mode); + return 1; /* granted with holding lh_lock */ + + out_enqueue: + list_del(&list); /* remove temprary head */ + return htree_node_lock_enqueue(lck, tmp2, dep, wait, event); +} + +/* + * release the key of @lck at level @dep, and grant any blocked locks. + * caller will still listen on @key if @event is not NULL, which means + * caller can see a event (by event_cb) while granting any lock with + * the same key at level @dep. + * NB: ALWAYS called holding lhead::lh_lock + * NB: listener will not block anyone because listening mode is HTREE_LOCK_NL + */ +static void +htree_node_unlock_internal(struct htree_lock_head *lhead, + struct htree_lock *curlk, unsigned dep, void *event) +{ + struct htree_lock_node *curln = &curlk->lk_nodes[dep]; + struct htree_lock *grtlk = NULL; + struct htree_lock_node *grtln; + struct htree_lock *poslk; + struct htree_lock *tmplk; + + if (!htree_node_is_granted(curlk, dep)) + return; + + if (!list_empty(&curln->ln_granted_list)) { + /* there is another granted lock */ + grtlk = list_entry(curln->ln_granted_list.next, + struct htree_lock, + lk_nodes[dep].ln_granted_list); + list_del_init(&curln->ln_granted_list); + } + + if (grtlk == NULL && !list_empty(&curln->ln_blocked_list)) { + /* + * @curlk is the only granted lock, so we confirmed: + * a) curln is key owner (attached on major/minor_list), + * so if there is any blocked lock, it should be attached + * on curln->ln_blocked_list + * b) we always can grant the first blocked lock + */ + grtlk = list_entry(curln->ln_blocked_list.next, + struct htree_lock, + lk_nodes[dep].ln_blocked_list); + BUG_ON(grtlk->lk_task == NULL); + wake_up_process(grtlk->lk_task); + } + + if (event != NULL && + lhead->lh_children[dep].lc_events != HTREE_EVENT_DISABLE) { + curln->ln_ev_target = event; + curln->ln_mode = HTREE_LOCK_NL; /* listen! */ + } else { + curln->ln_mode = HTREE_LOCK_INVAL; + } + + if (grtlk == NULL) { /* I must be the only one locking this key */ + struct htree_lock_node *tmpln; + + BUG_ON(htree_key_list_empty(curln)); + + if (curln->ln_mode == HTREE_LOCK_NL) /* listening */ + return; + + /* not listening */ + if (list_empty(&curln->ln_alive_list)) { /* no more listener */ + htree_key_list_del_init(curln); + return; + } + + tmpln = list_entry(curln->ln_alive_list.next, + struct htree_lock_node, ln_alive_list); + + BUG_ON(tmpln->ln_mode != HTREE_LOCK_NL); + + htree_key_list_replace_init(curln, tmpln); + list_del_init(&curln->ln_alive_list); + + return; + } + + /* have a granted lock */ + grtln = &grtlk->lk_nodes[dep]; + if (!list_empty(&curln->ln_blocked_list)) { + /* only key owner can be on both lists */ + BUG_ON(htree_key_list_empty(curln)); + + if (list_empty(&grtln->ln_blocked_list)) { + list_add(&grtln->ln_blocked_list, + &curln->ln_blocked_list); + } + list_del_init(&curln->ln_blocked_list); + } + /* + * NB: this is the tricky part: + * We have only two modes for child-lock (PR and PW), also, + * only owner of the key (attached on major/minor_list) can be on + * both blocked_list and granted_list, so @grtlk must be one + * of these two cases: + * + * a) @grtlk is taken from granted_list, which means we've granted + * more than one lock so @grtlk has to be PR, the first blocked + * lock must be PW and we can't grant it at all. + * So even @grtlk is not owner of the key (empty blocked_list), + * we don't care because we can't grant any lock. + * b) we just grant a new lock which is taken from head of blocked + * list, and it should be the first granted lock, and it should + * be the first one linked on blocked_list. + * + * Either way, we can get correct result by iterating blocked_list + * of @grtlk, and don't have to bother on how to find out + * owner of current key. + */ + list_for_each_entry_safe(poslk, tmplk, &grtln->ln_blocked_list, + lk_nodes[dep].ln_blocked_list) { + if (grtlk->lk_nodes[dep].ln_mode == HTREE_LOCK_PW || + poslk->lk_nodes[dep].ln_mode == HTREE_LOCK_PW) + break; + /* grant all readers */ + list_del_init(&poslk->lk_nodes[dep].ln_blocked_list); + list_add(&poslk->lk_nodes[dep].ln_granted_list, + &grtln->ln_granted_list); + + BUG_ON(poslk->lk_task == NULL); + wake_up_process(poslk->lk_task); + } + + /* if @curln is the owner of this key, replace it with @grtln */ + if (!htree_key_list_empty(curln)) + htree_key_list_replace_init(curln, grtln); + + if (curln->ln_mode == HTREE_LOCK_INVAL) + list_del_init(&curln->ln_alive_list); +} + +/* + * it's just wrapper of htree_node_lock_internal, it returns 1 on granted + * and 0 only if @wait is false and can't grant it immediately + */ +int +htree_node_lock_try(struct htree_lock *lck, htree_lock_mode_t mode, + u32 key, unsigned dep, int wait, void *event) +{ + struct htree_lock_head *lhead = lck->lk_head; + int rc; + + BUG_ON(dep >= lck->lk_depth); + BUG_ON(lck->lk_mode == HTREE_LOCK_INVAL); + + htree_spin_lock(lhead, dep); + rc = htree_node_lock_internal(lhead, lck, mode, key, dep, wait, event); + if (rc != 0) + htree_spin_unlock(lhead, dep); + return rc >= 0; +} +EXPORT_SYMBOL(htree_node_lock_try); + +/* it's wrapper of htree_node_unlock_internal */ +void +htree_node_unlock(struct htree_lock *lck, unsigned dep, void *event) +{ + struct htree_lock_head *lhead = lck->lk_head; + + BUG_ON(dep >= lck->lk_depth); + BUG_ON(lck->lk_mode == HTREE_LOCK_INVAL); + + htree_spin_lock(lhead, dep); + htree_node_unlock_internal(lhead, lck, dep, event); + htree_spin_unlock(lhead, dep); +} +EXPORT_SYMBOL(htree_node_unlock); + +/* stop listening on child-lock level @dep */ +void +htree_node_stop_listen(struct htree_lock *lck, unsigned dep) +{ + struct htree_lock_node *ln = &lck->lk_nodes[dep]; + struct htree_lock_node *tmp; + + BUG_ON(htree_node_is_granted(lck, dep)); + BUG_ON(!list_empty(&ln->ln_blocked_list)); + BUG_ON(!list_empty(&ln->ln_granted_list)); + + if (!htree_node_is_listening(lck, dep)) + return; + + htree_spin_lock(lck->lk_head, dep); + ln->ln_mode = HTREE_LOCK_INVAL; + ln->ln_ev_target = NULL; + + if (htree_key_list_empty(ln)) { /* not owner */ + list_del_init(&ln->ln_alive_list); + goto out; + } + + /* I'm the owner... */ + if (list_empty(&ln->ln_alive_list)) { /* no more listener */ + htree_key_list_del_init(ln); + goto out; + } + + tmp = list_entry(ln->ln_alive_list.next, + struct htree_lock_node, ln_alive_list); + + BUG_ON(tmp->ln_mode != HTREE_LOCK_NL); + htree_key_list_replace_init(ln, tmp); + list_del_init(&ln->ln_alive_list); + out: + htree_spin_unlock(lck->lk_head, dep); +} +EXPORT_SYMBOL(htree_node_stop_listen); + +/* release all child-locks if we have any */ +static void +htree_node_release_all(struct htree_lock *lck) +{ + int i; + + for (i = 0; i < lck->lk_depth; i++) { + if (htree_node_is_granted(lck, i)) + htree_node_unlock(lck, i, NULL); + else if (htree_node_is_listening(lck, i)) + htree_node_stop_listen(lck, i); + } +} + +/* + * obtain htree lock, it could be blocked inside if there's conflict + * with any granted or blocked lock and @wait is true. + * NB: ALWAYS called holding lhead::lh_lock + */ +static int +htree_lock_internal(struct htree_lock *lck, int wait) +{ + struct htree_lock_head *lhead = lck->lk_head; + int granted = 0; + int blocked = 0; + int i; + + for (i = 0; i < HTREE_LOCK_MAX; i++) { + if (lhead->lh_ngranted[i] != 0) + granted |= 1 << i; + if (lhead->lh_nblocked[i] != 0) + blocked |= 1 << i; + } + if ((htree_lock_compat[lck->lk_mode] & granted) != granted || + (htree_lock_compat[lck->lk_mode] & blocked) != blocked) { + /* will block current lock even it just conflicts with any + * other blocked lock, so lock like EX wouldn't starve */ + if (!wait) + return -1; + lhead->lh_nblocked[lck->lk_mode]++; + lk_block_inc(lck->lk_mode); + + lck->lk_task = current; + list_add_tail(&lck->lk_blocked_list, &lhead->lh_blocked_list); + +retry: + set_current_state(TASK_UNINTERRUPTIBLE); + htree_spin_unlock(lhead, HTREE_DEP_ROOT); + /* wait to be given the lock */ + if (lck->lk_task != NULL) + schedule(); + /* granted, no doubt. wake up will set me RUNNING. + * Since thread would be waken up accidentally, + * so we need check lock whether granted or not again. */ + if (!list_empty(&lck->lk_blocked_list)) { + htree_spin_lock(lhead, HTREE_DEP_ROOT); + if (list_empty(&lck->lk_blocked_list)) { + htree_spin_unlock(lhead, HTREE_DEP_ROOT); + return 0; + } + goto retry; + } + return 0; /* without lh_lock */ + } + lhead->lh_ngranted[lck->lk_mode]++; + lk_grant_inc(lck->lk_mode); + return 1; +} + +/* release htree lock. NB: ALWAYS called holding lhead::lh_lock */ +static void +htree_unlock_internal(struct htree_lock *lck) +{ + struct htree_lock_head *lhead = lck->lk_head; + struct htree_lock *tmp; + struct htree_lock *tmp2; + int granted = 0; + int i; + + BUG_ON(lhead->lh_ngranted[lck->lk_mode] == 0); + + lhead->lh_ngranted[lck->lk_mode]--; + lck->lk_mode = HTREE_LOCK_INVAL; + + for (i = 0; i < HTREE_LOCK_MAX; i++) { + if (lhead->lh_ngranted[i] != 0) + granted |= 1 << i; + } + list_for_each_entry_safe(tmp, tmp2, + &lhead->lh_blocked_list, lk_blocked_list) { + /* conflict with any granted lock? */ + if ((htree_lock_compat[tmp->lk_mode] & granted) != granted) + break; + + list_del_init(&tmp->lk_blocked_list); + + BUG_ON(lhead->lh_nblocked[tmp->lk_mode] == 0); + + lhead->lh_nblocked[tmp->lk_mode]--; + lhead->lh_ngranted[tmp->lk_mode]++; + granted |= 1 << tmp->lk_mode; + + BUG_ON(tmp->lk_task == NULL); + wake_up_process(tmp->lk_task); + } +} + +/* it's wrapper of htree_lock_internal and exported interface. + * It always return 1 with granted lock if @wait is true, it can return 0 + * if @wait is false and locking request can't be granted immediately */ +int +htree_lock_try(struct htree_lock *lck, struct htree_lock_head *lhead, + htree_lock_mode_t mode, int wait) +{ + int rc; + + BUG_ON(lck->lk_depth > lhead->lh_depth); + BUG_ON(lck->lk_head != NULL); + BUG_ON(lck->lk_task != NULL); + + lck->lk_head = lhead; + lck->lk_mode = mode; + + htree_spin_lock(lhead, HTREE_DEP_ROOT); + rc = htree_lock_internal(lck, wait); + if (rc != 0) + htree_spin_unlock(lhead, HTREE_DEP_ROOT); + return rc >= 0; +} +EXPORT_SYMBOL(htree_lock_try); + +/* it's wrapper of htree_unlock_internal and exported interface. + * It will release all htree_node_locks and htree_lock */ +void +htree_unlock(struct htree_lock *lck) +{ + BUG_ON(lck->lk_head == NULL); + BUG_ON(lck->lk_mode == HTREE_LOCK_INVAL); + + htree_node_release_all(lck); + + htree_spin_lock(lck->lk_head, HTREE_DEP_ROOT); + htree_unlock_internal(lck); + htree_spin_unlock(lck->lk_head, HTREE_DEP_ROOT); + lck->lk_head = NULL; + lck->lk_task = NULL; +} +EXPORT_SYMBOL(htree_unlock); + +/* change lock mode */ +void +htree_change_mode(struct htree_lock *lck, htree_lock_mode_t mode) +{ + BUG_ON(lck->lk_mode == HTREE_LOCK_INVAL); + lck->lk_mode = mode; +} +EXPORT_SYMBOL(htree_change_mode); + +/* release htree lock, and lock it again with new mode. + * This function will first release all htree_node_locks and htree_lock, + * then try to gain htree_lock with new @mode. + * It always return 1 with granted lock if @wait is true, it can return 0 + * if @wait is false and locking request can't be granted immediately */ +int +htree_change_lock_try(struct htree_lock *lck, htree_lock_mode_t mode, int wait) +{ + struct htree_lock_head *lhead = lck->lk_head; + int rc; + + BUG_ON(lhead == NULL); + BUG_ON(lck->lk_mode == mode); + BUG_ON(lck->lk_mode == HTREE_LOCK_INVAL || mode == HTREE_LOCK_INVAL); + + htree_node_release_all(lck); + + htree_spin_lock(lhead, HTREE_DEP_ROOT); + htree_unlock_internal(lck); + lck->lk_mode = mode; + rc = htree_lock_internal(lck, wait); + if (rc != 0) + htree_spin_unlock(lhead, HTREE_DEP_ROOT); + return rc >= 0; +} +EXPORT_SYMBOL(htree_change_lock_try); + +/* create a htree_lock head with @depth levels (number of child-locks), + * it is a per resoruce structure */ +struct htree_lock_head * +htree_lock_head_alloc(unsigned depth, unsigned hbits, unsigned priv) +{ + struct htree_lock_head *lhead; + int i; + + if (depth > HTREE_LOCK_DEP_MAX) { + printk(KERN_ERR "%d is larger than max htree_lock depth %d\n", + depth, HTREE_LOCK_DEP_MAX); + return NULL; + } + + lhead = kzalloc(offsetof(struct htree_lock_head, + lh_children[depth]) + priv, GFP_NOFS); + if (lhead == NULL) + return NULL; + + if (hbits < HTREE_HBITS_MIN) + lhead->lh_hbits = HTREE_HBITS_MIN; + else if (hbits > HTREE_HBITS_MAX) + lhead->lh_hbits = HTREE_HBITS_MAX; + + lhead->lh_lock = 0; + lhead->lh_depth = depth; + INIT_LIST_HEAD(&lhead->lh_blocked_list); + if (priv > 0) { + lhead->lh_private = (void *)lhead + + offsetof(struct htree_lock_head, lh_children[depth]); + } + + for (i = 0; i < depth; i++) { + INIT_LIST_HEAD(&lhead->lh_children[i].lc_list); + lhead->lh_children[i].lc_events = HTREE_EVENT_DISABLE; + } + return lhead; +} +EXPORT_SYMBOL(htree_lock_head_alloc); + +/* free the htree_lock head */ +void +htree_lock_head_free(struct htree_lock_head *lhead) +{ + int i; + + BUG_ON(!list_empty(&lhead->lh_blocked_list)); + for (i = 0; i < lhead->lh_depth; i++) + BUG_ON(!list_empty(&lhead->lh_children[i].lc_list)); + kfree(lhead); +} +EXPORT_SYMBOL(htree_lock_head_free); + +/* register event callback for @events of child-lock at level @dep */ +void +htree_lock_event_attach(struct htree_lock_head *lhead, unsigned dep, + unsigned events, htree_event_cb_t callback) +{ + BUG_ON(lhead->lh_depth <= dep); + lhead->lh_children[dep].lc_events = events; + lhead->lh_children[dep].lc_callback = callback; +} +EXPORT_SYMBOL(htree_lock_event_attach); + +/* allocate a htree_lock, which is per-thread structure, @pbytes is some + * extra-bytes as private data for caller */ +struct htree_lock * +htree_lock_alloc(unsigned depth, unsigned pbytes) +{ + struct htree_lock *lck; + int i = offsetof(struct htree_lock, lk_nodes[depth]); + + if (depth > HTREE_LOCK_DEP_MAX) { + printk(KERN_ERR "%d is larger than max htree_lock depth %d\n", + depth, HTREE_LOCK_DEP_MAX); + return NULL; + } + lck = kzalloc(i + pbytes, GFP_NOFS); + if (lck == NULL) + return NULL; + + if (pbytes != 0) + lck->lk_private = (void *)lck + i; + lck->lk_mode = HTREE_LOCK_INVAL; + lck->lk_depth = depth; + INIT_LIST_HEAD(&lck->lk_blocked_list); + + for (i = 0; i < depth; i++) { + struct htree_lock_node *node = &lck->lk_nodes[i]; + + node->ln_mode = HTREE_LOCK_INVAL; + INIT_LIST_HEAD(&node->ln_major_list); + INIT_LIST_HEAD(&node->ln_minor_list); + INIT_LIST_HEAD(&node->ln_alive_list); + INIT_LIST_HEAD(&node->ln_blocked_list); + INIT_LIST_HEAD(&node->ln_granted_list); + } + + return lck; +} +EXPORT_SYMBOL(htree_lock_alloc); + +/* free htree_lock node */ +void +htree_lock_free(struct htree_lock *lck) +{ + BUG_ON(lck->lk_mode != HTREE_LOCK_INVAL); + kfree(lck); +} +EXPORT_SYMBOL(htree_lock_free); diff --git a/fs/ext4/htree_lock.h b/fs/ext4/htree_lock.h new file mode 100644 index 0000000..9dc7788 --- /dev/null +++ b/fs/ext4/htree_lock.h @@ -0,0 +1,187 @@ +/* + * include/linux/htree_lock.h + * + * Copyright (c) 2011, 2012, Intel Corporation. + * + * Author: Liang Zhen + */ + +/* + * htree lock + * + * htree_lock is an advanced lock, it can support five lock modes (concept is + * taken from DLM) and it's a sleeping lock. + * + * most common use case is: + * - create a htree_lock_head for data + * - each thread (contender) creates it's own htree_lock + * - contender needs to call htree_lock(lock_node, mode) to protect data and + * call htree_unlock to release lock + * + * Also, there is advanced use-case which is more complex, user can have + * PW/PR lock on particular key, it's mostly used while user holding shared + * lock on the htree (CW, CR) + * + * htree_lock(lock_node, HTREE_LOCK_CR); lock the htree with CR + * htree_node_lock(lock_node, HTREE_LOCK_PR, key...); lock @key with PR + * ... + * htree_node_unlock(lock_node);; unlock the key + * + * Another tip is, we can have N-levels of this kind of keys, all we need to + * do is specifying N-levels while creating htree_lock_head, then we can + * lock/unlock a specific level by: + * htree_node_lock(lock_node, mode1, key1, level1...); + * do something; + * htree_node_lock(lock_node, mode1, key2, level2...); + * do something; + * htree_node_unlock(lock_node, level2); + * htree_node_unlock(lock_node, level1); + * + * NB: for multi-level, should be careful about locking order to avoid deadlock + */ + +#ifndef _LINUX_HTREE_LOCK_H +#define _LINUX_HTREE_LOCK_H + +#include +#include +#include + +/* + * Lock Modes + * more details can be found here: + * http://en.wikipedia.org/wiki/Distributed_lock_manager + */ +typedef enum { + HTREE_LOCK_EX = 0, /* exclusive lock: incompatible with all others */ + HTREE_LOCK_PW, /* protected write: allows only CR users */ + HTREE_LOCK_PR, /* protected read: allow PR, CR users */ + HTREE_LOCK_CW, /* concurrent write: allow CR, CW users */ + HTREE_LOCK_CR, /* concurrent read: allow all but EX users */ + HTREE_LOCK_MAX, /* number of lock modes */ +} htree_lock_mode_t; + +#define HTREE_LOCK_NL HTREE_LOCK_MAX +#define HTREE_LOCK_INVAL 0xdead10c + +enum { + HTREE_HBITS_MIN = 2, + HTREE_HBITS_DEF = 14, + HTREE_HBITS_MAX = 32, +}; + +enum { + HTREE_EVENT_DISABLE = (0), + HTREE_EVENT_RD = (1 << HTREE_LOCK_PR), + HTREE_EVENT_WR = (1 << HTREE_LOCK_PW), + HTREE_EVENT_RDWR = (HTREE_EVENT_RD | HTREE_EVENT_WR), +}; + +struct htree_lock; + +typedef void (*htree_event_cb_t)(void *target, void *event); + +struct htree_lock_child { + struct list_head lc_list; /* granted list */ + htree_event_cb_t lc_callback; /* event callback */ + unsigned lc_events; /* event types */ +}; + +struct htree_lock_head { + unsigned long lh_lock; /* bits lock */ + /* blocked lock list (htree_lock) */ + struct list_head lh_blocked_list; + /* # key levels */ + u16 lh_depth; + /* hash bits for key and limit number of locks */ + u16 lh_hbits; + /* counters for blocked locks */ + u16 lh_nblocked[HTREE_LOCK_MAX]; + /* counters for granted locks */ + u16 lh_ngranted[HTREE_LOCK_MAX]; + /* private data */ + void *lh_private; + /* array of children locks */ + struct htree_lock_child lh_children[0]; +}; + +/* htree_lock_node_t is child-lock for a specific key (ln_value) */ +struct htree_lock_node { + htree_lock_mode_t ln_mode; + /* major hash key */ + u16 ln_major_key; + /* minor hash key */ + u16 ln_minor_key; + struct list_head ln_major_list; + struct list_head ln_minor_list; + /* alive list, all locks (granted, blocked, listening) are on it */ + struct list_head ln_alive_list; + /* blocked list */ + struct list_head ln_blocked_list; + /* granted list */ + struct list_head ln_granted_list; + void *ln_ev_target; +}; + +struct htree_lock { + struct task_struct *lk_task; + struct htree_lock_head *lk_head; + void *lk_private; + unsigned lk_depth; + htree_lock_mode_t lk_mode; + struct list_head lk_blocked_list; + struct htree_lock_node lk_nodes[0]; +}; + +/* create a lock head, which stands for a resource */ +struct htree_lock_head *htree_lock_head_alloc(unsigned depth, + unsigned hbits, unsigned priv); +/* free a lock head */ +void htree_lock_head_free(struct htree_lock_head *lhead); +/* register event callback for child lock at level @depth */ +void htree_lock_event_attach(struct htree_lock_head *lhead, unsigned depth, + unsigned events, htree_event_cb_t callback); +/* create a lock handle, which stands for a thread */ +struct htree_lock *htree_lock_alloc(unsigned depth, unsigned pbytes); +/* free a lock handle */ +void htree_lock_free(struct htree_lock *lck); +/* lock htree, when @wait is true, 0 is returned if the lock can't + * be granted immediately */ +int htree_lock_try(struct htree_lock *lck, struct htree_lock_head *lhead, + htree_lock_mode_t mode, int wait); +/* unlock htree */ +void htree_unlock(struct htree_lock *lck); +/* unlock and relock htree with @new_mode */ +int htree_change_lock_try(struct htree_lock *lck, + htree_lock_mode_t new_mode, int wait); +void htree_change_mode(struct htree_lock *lck, htree_lock_mode_t mode); +/* require child lock (key) of htree at level @dep, @event will be sent to all + * listeners on this @key while lock being granted */ +int htree_node_lock_try(struct htree_lock *lck, htree_lock_mode_t mode, + u32 key, unsigned dep, int wait, void *event); +/* release child lock at level @dep, this lock will listen on it's key + * if @event isn't NULL, event_cb will be called against @lck while granting + * any other lock at level @dep with the same key */ +void htree_node_unlock(struct htree_lock *lck, unsigned dep, void *event); +/* stop listening on child lock at level @dep */ +void htree_node_stop_listen(struct htree_lock *lck, unsigned dep); +/* for debug */ +void htree_lock_stat_print(int depth); +void htree_lock_stat_reset(void); + +#define htree_lock(lck, lh, mode) htree_lock_try(lck, lh, mode, 1) +#define htree_change_lock(lck, mode) htree_change_lock_try(lck, mode, 1) + +#define htree_lock_mode(lck) ((lck)->lk_mode) + +#define htree_node_lock(lck, mode, key, dep) \ + htree_node_lock_try(lck, mode, key, dep, 1, NULL) +/* this is only safe in thread context of lock owner */ +#define htree_node_is_granted(lck, dep) \ + ((lck)->lk_nodes[dep].ln_mode != HTREE_LOCK_INVAL && \ + (lck)->lk_nodes[dep].ln_mode != HTREE_LOCK_NL) +/* this is only safe in thread context of lock owner */ +#define htree_node_is_listening(lck, dep) \ + ((lck)->lk_nodes[dep].ln_mode == HTREE_LOCK_NL) + +#endif diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 9cb86e4..0153c4d 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -54,6 +54,7 @@ struct buffer_head *ext4_append(handle_t *handle, struct inode *inode, ext4_lblk_t *block) { + struct ext4_inode_info *ei = EXT4_I(inode); struct buffer_head *bh; int err; @@ -62,15 +63,24 @@ struct buffer_head *ext4_append(handle_t *handle, EXT4_SB(inode->i_sb)->s_max_dir_size_kb))) return ERR_PTR(-ENOSPC); + /* with parallel dir operations all appends + * have to be serialized -bzzz + */ + down(&ei->i_append_sem); + *block = inode->i_size >> inode->i_sb->s_blocksize_bits; bh = ext4_bread(handle, inode, *block, EXT4_GET_BLOCKS_CREATE); - if (IS_ERR(bh)) + if (IS_ERR(bh)) { + up(&ei->i_append_sem); return bh; + } + inode->i_size += inode->i_sb->s_blocksize; EXT4_I(inode)->i_disksize = inode->i_size; BUFFER_TRACE(bh, "get_write_access"); err = ext4_journal_get_write_access(handle, bh); + up(&ei->i_append_sem); if (err) { brelse(bh); ext4_std_error(inode->i_sb, err); @@ -250,7 +260,8 @@ static unsigned int inline dx_root_limit(struct inode *dir, static struct dx_frame *dx_probe(struct ext4_filename *fname, struct inode *dir, struct dx_hash_info *hinfo, - struct dx_frame *frame); + struct dx_frame *frame, + struct htree_lock *lck); static void dx_release(struct dx_frame *frames); static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de, unsigned blocksize, struct dx_hash_info *hinfo, @@ -264,12 +275,13 @@ static void dx_insert_block(struct dx_frame *frame, static int ext4_htree_next_block(struct inode *dir, __u32 hash, struct dx_frame *frame, struct dx_frame *frames, - __u32 *start_hash); + __u32 *start_hash, struct htree_lock *lck); static struct buffer_head * ext4_dx_find_entry(struct inode *dir, struct ext4_filename *fname, - struct ext4_dir_entry_2 **res_dir); + struct ext4_dir_entry_2 **res_dir, struct htree_lock *lck); static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname, - struct inode *dir, struct inode *inode); + struct inode *dir, struct inode *inode, + struct htree_lock *lck); /* checksumming functions */ void initialize_dirent_tail(struct ext4_dir_entry_tail *t, @@ -734,6 +746,226 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir, } #endif /* DX_DEBUG */ +/* private data for htree_lock */ +struct ext4_dir_lock_data { + unsigned int ld_flags; /* bits-map for lock types */ + unsigned int ld_count; /* # entries of the last DX block */ + struct dx_entry ld_at_entry; /* copy of leaf dx_entry */ + struct dx_entry *ld_at; /* position of leaf dx_entry */ +}; + +#define ext4_htree_lock_data(l) ((struct ext4_dir_lock_data *)(l)->lk_private) +#define ext4_find_entry(dir, name, dirent, inline) \ + ext4_find_entry_locked(dir, name, dirent, inline, NULL) +#define ext4_add_entry(handle, dentry, inode) \ + ext4_add_entry_locked(handle, dentry, inode, NULL) + +/* NB: ext4_lblk_t is 32 bits so we use high bits to identify invalid blk */ +#define EXT4_HTREE_NODE_CHANGED (0xcafeULL << 32) + +static void ext4_htree_event_cb(void *target, void *event) +{ + u64 *block = (u64 *)target; + + if (*block == dx_get_block((struct dx_entry *)event)) + *block = EXT4_HTREE_NODE_CHANGED; +} + +struct htree_lock_head *ext4_htree_lock_head_alloc(unsigned hbits) +{ + struct htree_lock_head *lhead; + + lhead = htree_lock_head_alloc(EXT4_LK_MAX, hbits, 0); + if (lhead) { + htree_lock_event_attach(lhead, EXT4_LK_SPIN, HTREE_EVENT_WR, + ext4_htree_event_cb); + } + return lhead; +} +EXPORT_SYMBOL(ext4_htree_lock_head_alloc); + +struct htree_lock *ext4_htree_lock_alloc(void) +{ + return htree_lock_alloc(EXT4_LK_MAX, + sizeof(struct ext4_dir_lock_data)); +} +EXPORT_SYMBOL(ext4_htree_lock_alloc); + +static htree_lock_mode_t ext4_htree_mode(unsigned flags) +{ + switch (flags) { + default: /* 0 or unknown flags require EX lock */ + return HTREE_LOCK_EX; + case EXT4_HLOCK_READDIR: + return HTREE_LOCK_PR; + case EXT4_HLOCK_LOOKUP: + return HTREE_LOCK_CR; + case EXT4_HLOCK_DEL: + case EXT4_HLOCK_ADD: + return HTREE_LOCK_CW; + } +} + +/* return PR for read-only operations, otherwise return EX */ +static inline htree_lock_mode_t ext4_htree_safe_mode(unsigned flags) +{ + int writer = (flags & EXT4_LB_DE) == EXT4_LB_DE; + + /* 0 requires EX lock */ + return (flags == 0 || writer) ? HTREE_LOCK_EX : HTREE_LOCK_PR; +} + +static int ext4_htree_safe_locked(struct htree_lock *lck) +{ + int writer; + + if (!lck || lck->lk_mode == HTREE_LOCK_EX) + return 1; + + writer = (ext4_htree_lock_data(lck)->ld_flags & EXT4_LB_DE) == + EXT4_LB_DE; + if (writer) /* all readers & writers are excluded? */ + return lck->lk_mode == HTREE_LOCK_EX; + + /* all writers are excluded? */ + return lck->lk_mode == HTREE_LOCK_PR || + lck->lk_mode == HTREE_LOCK_PW || + lck->lk_mode == HTREE_LOCK_EX; +} + +/* relock htree_lock with EX mode if it's change operation, otherwise + * relock it with PR mode. It's noop if PDO is disabled. + */ +static void ext4_htree_safe_relock(struct htree_lock *lck) +{ + if (!ext4_htree_safe_locked(lck)) { + unsigned int flags = ext4_htree_lock_data(lck)->ld_flags; + + htree_change_lock(lck, ext4_htree_safe_mode(flags)); + } +} + +void ext4_htree_lock(struct htree_lock *lck, struct htree_lock_head *lhead, + struct inode *dir, unsigned flags) +{ + htree_lock_mode_t mode = is_dx(dir) ? ext4_htree_mode(flags) : + ext4_htree_safe_mode(flags); + + ext4_htree_lock_data(lck)->ld_flags = flags; + htree_lock(lck, lhead, mode); + if (!is_dx(dir)) + ext4_htree_safe_relock(lck); /* make sure it's safe locked */ +} +EXPORT_SYMBOL(ext4_htree_lock); + +static int ext4_htree_node_lock(struct htree_lock *lck, struct dx_entry *at, + unsigned int lmask, int wait, void *ev) +{ + u32 key = (at == NULL) ? 0 : dx_get_block(at); + u32 mode; + + /* NOOP if htree is well protected or caller doesn't require the lock */ + if (ext4_htree_safe_locked(lck) || + !(ext4_htree_lock_data(lck)->ld_flags & lmask)) + return 1; + + mode = (ext4_htree_lock_data(lck)->ld_flags & lmask) == lmask ? + HTREE_LOCK_PW : HTREE_LOCK_PR; + while (1) { + if (htree_node_lock_try(lck, mode, key, ffz(~lmask), wait, ev)) + return 1; + if (!(lmask & EXT4_LB_SPIN)) /* not a spinlock */ + return 0; + cpu_relax(); /* spin until granted */ + } +} + +static int ext4_htree_node_locked(struct htree_lock *lck, unsigned lmask) +{ + return ext4_htree_safe_locked(lck) || + htree_node_is_granted(lck, ffz(~lmask)); +} + +static void ext4_htree_node_unlock(struct htree_lock *lck, + unsigned int lmask, void *buf) +{ + /* NB: it's safe to call mutiple times or even it's not locked */ + if (!ext4_htree_safe_locked(lck) && + htree_node_is_granted(lck, ffz(~lmask))) + htree_node_unlock(lck, ffz(~lmask), buf); +} + +#define ext4_htree_dx_lock(lck, key) \ + ext4_htree_node_lock(lck, key, EXT4_LB_DX, 1, NULL) +#define ext4_htree_dx_lock_try(lck, key) \ + ext4_htree_node_lock(lck, key, EXT4_LB_DX, 0, NULL) +#define ext4_htree_dx_unlock(lck) \ + ext4_htree_node_unlock(lck, EXT4_LB_DX, NULL) +#define ext4_htree_dx_locked(lck) \ + ext4_htree_node_locked(lck, EXT4_LB_DX) + +static void ext4_htree_dx_need_lock(struct htree_lock *lck) +{ + struct ext4_dir_lock_data *ld; + + if (ext4_htree_safe_locked(lck)) + return; + + ld = ext4_htree_lock_data(lck); + switch (ld->ld_flags) { + default: + return; + case EXT4_HLOCK_LOOKUP: + ld->ld_flags = EXT4_HLOCK_LOOKUP_SAFE; + return; + case EXT4_HLOCK_DEL: + ld->ld_flags = EXT4_HLOCK_DEL_SAFE; + return; + case EXT4_HLOCK_ADD: + ld->ld_flags = EXT4_HLOCK_SPLIT; + return; + } +} + +#define ext4_htree_de_lock(lck, key) \ + ext4_htree_node_lock(lck, key, EXT4_LB_DE, 1, NULL) +#define ext4_htree_de_unlock(lck) \ + ext4_htree_node_unlock(lck, EXT4_LB_DE, NULL) + +#define ext4_htree_spin_lock(lck, key, event) \ + ext4_htree_node_lock(lck, key, EXT4_LB_SPIN, 0, event) +#define ext4_htree_spin_unlock(lck) \ + ext4_htree_node_unlock(lck, EXT4_LB_SPIN, NULL) +#define ext4_htree_spin_unlock_listen(lck, p) \ + ext4_htree_node_unlock(lck, EXT4_LB_SPIN, p) + +static void ext4_htree_spin_stop_listen(struct htree_lock *lck) +{ + if (!ext4_htree_safe_locked(lck) && + htree_node_is_listening(lck, ffz(~EXT4_LB_SPIN))) + htree_node_stop_listen(lck, ffz(~EXT4_LB_SPIN)); +} + +enum { + DX_HASH_COL_IGNORE, /* ignore collision while probing frames */ + DX_HASH_COL_YES, /* there is collision and it does matter */ + DX_HASH_COL_NO, /* there is no collision */ +}; + +static int dx_probe_hash_collision(struct htree_lock *lck, + struct dx_entry *entries, + struct dx_entry *at, u32 hash) +{ + if (!(lck && ext4_htree_lock_data(lck)->ld_flags & EXT4_LB_EXACT)) { + return DX_HASH_COL_IGNORE; /* don't care about collision */ + } else if (at == entries + dx_get_count(entries) - 1) { + return DX_HASH_COL_IGNORE; /* not in any leaf of this DX */ + } else { /* hash collision? */ + return ((dx_get_hash(at + 1) & ~1) == hash) ? + DX_HASH_COL_YES : DX_HASH_COL_NO; + } +} + /* * Probe for a directory leaf block to search. * @@ -745,10 +977,11 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir, */ static struct dx_frame * dx_probe(struct ext4_filename *fname, struct inode *dir, - struct dx_hash_info *hinfo, struct dx_frame *frame_in) + struct dx_hash_info *hinfo, struct dx_frame *frame_in, + struct htree_lock *lck) { unsigned count, indirect; - struct dx_entry *at, *entries, *p, *q, *m; + struct dx_entry *at, *entries, *p, *q, *m, *dx = NULL; struct dx_root_info *info; struct dx_frame *frame = frame_in; struct dx_frame *ret_err = ERR_PTR(ERR_BAD_DX_DIR); @@ -811,6 +1044,13 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir, dxtrace(printk("Look up %x", hash)); while (1) { + if (indirect == 0) { /* the last index level */ + /* NB: ext4_htree_dx_lock() could be noop if + * DX-lock flag is not set for current operation + */ + ext4_htree_dx_lock(lck, dx); + ext4_htree_spin_lock(lck, dx, NULL); + } count = dx_get_count(entries); if (!count || count > dx_get_limit(entries)) { ext4_warning_inode(dir, @@ -851,8 +1091,75 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir, dx_get_block(at))); frame->entries = entries; frame->at = at; - if (!indirect--) + + if (indirect == 0) { /* the last index level */ + struct ext4_dir_lock_data *ld; + u64 myblock; + + /* By default we only lock DE-block, however, we will + * also lock the last level DX-block if: + * a) there is hash collision + * we will set DX-lock flag (a few lines below) + * and redo to lock DX-block + * see detail in dx_probe_hash_collision() + * b) it's a retry from splitting + * we need to lock the last level DX-block so nobody + * else can split any leaf blocks under the same + * DX-block, see detail in ext4_dx_add_entry() + */ + if (ext4_htree_dx_locked(lck)) { + /* DX-block is locked, just lock DE-block + * and return + */ + ext4_htree_spin_unlock(lck); + if (!ext4_htree_safe_locked(lck)) + ext4_htree_de_lock(lck, frame->at); + return frame; + } + /* it's pdirop and no DX lock */ + if (dx_probe_hash_collision(lck, entries, at, hash) == + DX_HASH_COL_YES) { + /* found hash collision, set DX-lock flag + * and retry to abtain DX-lock + */ + ext4_htree_spin_unlock(lck); + ext4_htree_dx_need_lock(lck); + continue; + } + ld = ext4_htree_lock_data(lck); + /* because I don't lock DX, so @at can't be trusted + * after I release spinlock so I have to save it + */ + ld->ld_at = at; + ld->ld_at_entry = *at; + ld->ld_count = dx_get_count(entries); + + frame->at = &ld->ld_at_entry; + myblock = dx_get_block(at); + + /* NB: ordering locking */ + ext4_htree_spin_unlock_listen(lck, &myblock); + /* other thread can split this DE-block because: + * a) I don't have lock for the DE-block yet + * b) I released spinlock on DX-block + * if it happened I can detect it by listening + * splitting event on this DE-block + */ + ext4_htree_de_lock(lck, frame->at); + ext4_htree_spin_stop_listen(lck); + + if (myblock == EXT4_HTREE_NODE_CHANGED) { + /* someone split this DE-block before + * I locked it, I need to retry and lock + * valid DE-block + */ + ext4_htree_de_unlock(lck); + continue; + } return frame; + } + dx = at; + indirect--; frame++; frame->bh = ext4_read_dirblock(dir, dx_get_block(at), INDEX); if (IS_ERR(frame->bh)) { @@ -921,7 +1228,7 @@ static void dx_release(struct dx_frame *frames) static int ext4_htree_next_block(struct inode *dir, __u32 hash, struct dx_frame *frame, struct dx_frame *frames, - __u32 *start_hash) + u32 *start_hash, struct htree_lock *lck) { struct dx_frame *p; struct buffer_head *bh; @@ -936,12 +1243,23 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash, * this loop, num_frames indicates the number of interior * nodes need to be read. */ + ext4_htree_de_unlock(lck); while (1) { - if (++(p->at) < p->entries + dx_get_count(p->entries)) - break; + if (num_frames > 0 || ext4_htree_dx_locked(lck)) { + /* num_frames > 0 : + * DX block + * ext4_htree_dx_locked: + * frame->at is reliable pointer returned by dx_probe, + * otherwise dx_probe already knew no collision + */ + if (++(p->at) < p->entries + dx_get_count(p->entries)) + break; + } if (p == frames) return 0; num_frames++; + if (num_frames == 1) + ext4_htree_dx_unlock(lck); p--; } @@ -964,6 +1282,14 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash, * block so no check is necessary */ while (num_frames--) { + if (num_frames == 0) { + /* it's not always necessary, we just don't want to + * detect hash collision again + */ + ext4_htree_dx_need_lock(lck); + ext4_htree_dx_lock(lck, p->at); + } + bh = ext4_read_dirblock(dir, dx_get_block(p->at), INDEX); if (IS_ERR(bh)) return PTR_ERR(bh); @@ -972,10 +1298,10 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash, p->bh = bh; p->at = p->entries = ((struct dx_node *) bh->b_data)->entries; } + ext4_htree_de_lock(lck, p->at); return 1; } - /* * This function fills a red-black tree with information from a * directory block. It returns the number directory entries loaded @@ -1119,7 +1445,8 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash, } hinfo.hash = start_hash; hinfo.minor_hash = 0; - frame = dx_probe(NULL, dir, &hinfo, frames); + /* assume it's PR locked */ + frame = dx_probe(NULL, dir, &hinfo, frames, NULL); if (IS_ERR(frame)) return PTR_ERR(frame); @@ -1162,7 +1489,7 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash, count += ret; hashval = ~0; ret = ext4_htree_next_block(dir, HASH_NB_ALWAYS, - frame, frames, &hashval); + frame, frames, &hashval, NULL); *next_hash = hashval; if (ret < 0) { err = ret; @@ -1400,7 +1727,7 @@ static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block, static struct buffer_head *__ext4_find_entry(struct inode *dir, struct ext4_filename *fname, struct ext4_dir_entry_2 **res_dir, - int *inlined) + int *inlined, struct htree_lock *lck) { struct super_block *sb; struct buffer_head *bh_use[NAMEI_RA_SIZE]; @@ -1442,7 +1769,7 @@ static struct buffer_head *__ext4_find_entry(struct inode *dir, goto restart; } if (is_dx(dir)) { - ret = ext4_dx_find_entry(dir, fname, res_dir); + ret = ext4_dx_find_entry(dir, fname, res_dir, lck); /* * On success, or if the error was file not found, * return. Otherwise, fall back to doing a search the @@ -1452,6 +1779,7 @@ static struct buffer_head *__ext4_find_entry(struct inode *dir, goto cleanup_and_exit; dxtrace(printk(KERN_DEBUG "ext4_find_entry: dx failed, " "falling back\n")); + ext4_htree_safe_relock(lck); ret = NULL; } nblocks = dir->i_size >> EXT4_BLOCK_SIZE_BITS(sb); @@ -1540,10 +1868,10 @@ static struct buffer_head *__ext4_find_entry(struct inode *dir, return ret; } -static struct buffer_head *ext4_find_entry(struct inode *dir, +struct buffer_head *ext4_find_entry_locked(struct inode *dir, const struct qstr *d_name, struct ext4_dir_entry_2 **res_dir, - int *inlined) + int *inlined, struct htree_lock *lck) { int err; struct ext4_filename fname; @@ -1555,11 +1883,12 @@ static struct buffer_head *ext4_find_entry(struct inode *dir, if (err) return ERR_PTR(err); - bh = __ext4_find_entry(dir, &fname, res_dir, inlined); + bh = __ext4_find_entry(dir, &fname, res_dir, inlined, lck); ext4_fname_free_filename(&fname); return bh; } +EXPORT_SYMBOL(ext4_find_entry_locked); static struct buffer_head *ext4_lookup_entry(struct inode *dir, struct dentry *dentry, @@ -1575,7 +1904,7 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir, if (err) return ERR_PTR(err); - bh = __ext4_find_entry(dir, &fname, res_dir, NULL); + bh = __ext4_find_entry(dir, &fname, res_dir, NULL, NULL); ext4_fname_free_filename(&fname); return bh; @@ -1583,7 +1912,8 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir, static struct buffer_head * ext4_dx_find_entry(struct inode *dir, struct ext4_filename *fname, - struct ext4_dir_entry_2 **res_dir) + struct ext4_dir_entry_2 **res_dir, + struct htree_lock *lck) { struct super_block * sb = dir->i_sb; struct dx_frame frames[EXT4_HTREE_LEVEL], *frame; @@ -1594,7 +1924,7 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir, #ifdef CONFIG_FS_ENCRYPTION *res_dir = NULL; #endif - frame = dx_probe(fname, dir, NULL, frames); + frame = dx_probe(fname, dir, NULL, frames, lck); if (IS_ERR(frame)) return (struct buffer_head *) frame; do { @@ -1616,7 +1946,7 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir, /* Check to see if we should continue to search */ retval = ext4_htree_next_block(dir, fname->hinfo.hash, frame, - frames, NULL); + frames, NULL, lck); if (retval < 0) { ext4_warning_inode(dir, "error %d reading directory index block", @@ -1799,8 +2129,9 @@ static struct ext4_dir_entry_2* dx_pack_dirents(char *base, unsigned blocksize) * Returns pointer to de in block into which the new entry will be inserted. */ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir, - struct buffer_head **bh,struct dx_frame *frame, - struct dx_hash_info *hinfo) + struct buffer_head **bh, struct dx_frame *frames, + struct dx_frame *frame, struct dx_hash_info *hinfo, + struct htree_lock *lck) { unsigned blocksize = dir->i_sb->s_blocksize; unsigned count, continued; @@ -1862,8 +2193,15 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir, hash2, split, count-split)); /* Fancy dance to stay within two buffers */ - de2 = dx_move_dirents(data1, data2, map + split, count - split, - blocksize); + if (hinfo->hash < hash2) { + de2 = dx_move_dirents(data1, data2, map + split, + count - split, blocksize); + } else { + /* make sure we will add entry to the same block which + * we have already locked + */ + de2 = dx_move_dirents(data1, data2, map, split, blocksize); + } de = dx_pack_dirents(data1, blocksize); de->rec_len = ext4_rec_len_to_disk(data1 + (blocksize - csum_size) - (char *) de, @@ -1884,12 +2222,20 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir, dxtrace(dx_show_leaf(dir, hinfo, (struct ext4_dir_entry_2 *) data2, blocksize, 1)); - /* Which block gets the new entry? */ - if (hinfo->hash >= hash2) { - swap(*bh, bh2); - de = de2; + ext4_htree_spin_lock(lck, frame > frames ? (frame - 1)->at : NULL, + frame->at); /* notify block is being split */ + if (hinfo->hash < hash2) { + dx_insert_block(frame, hash2 + continued, newblock); + } else { + /* switch block number */ + dx_insert_block(frame, hash2 + continued, + dx_get_block(frame->at)); + dx_set_block(frame->at, newblock); + (frame->at)++; } - dx_insert_block(frame, hash2 + continued, newblock); + ext4_htree_spin_unlock(lck); + ext4_htree_dx_unlock(lck); + err = ext4_handle_dirty_dirent_node(handle, dir, bh2); if (err) goto journal_error; @@ -2167,7 +2513,7 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname, if (retval) goto out_frames; - de = do_split(handle,dir, &bh2, frame, &fname->hinfo); + de = do_split(handle, dir, &bh2, frames, frame, &fname->hinfo, NULL); if (IS_ERR(de)) { retval = PTR_ERR(de); goto out_frames; @@ -2276,8 +2622,8 @@ static int ext4_update_dotdot(handle_t *handle, struct dentry *dentry, * may not sleep between calling this and putting something into * the entry, as someone else might have used it while you slept. */ -static int ext4_add_entry(handle_t *handle, struct dentry *dentry, - struct inode *inode) +int ext4_add_entry_locked(handle_t *handle, struct dentry *dentry, + struct inode *inode, struct htree_lock *lck) { struct inode *dir = d_inode(dentry->d_parent); struct buffer_head *bh = NULL; @@ -2326,9 +2672,10 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry, if (dentry->d_name.len == 2 && memcmp(dentry->d_name.name, "..", 2) == 0) return ext4_update_dotdot(handle, dentry, inode); - retval = ext4_dx_add_entry(handle, &fname, dir, inode); + retval = ext4_dx_add_entry(handle, &fname, dir, inode, lck); if (!retval || (retval != ERR_BAD_DX_DIR)) goto out; + ext4_htree_safe_relock(lck); ext4_clear_inode_flag(dir, EXT4_INODE_INDEX); dx_fallback++; ext4_mark_inode_dirty(handle, dir); @@ -2378,12 +2725,14 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry, ext4_set_inode_state(inode, EXT4_STATE_NEWENTRY); return retval; } +EXPORT_SYMBOL(ext4_add_entry_locked); /* * Returns 0 for success, or a negative error value */ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname, - struct inode *dir, struct inode *inode) + struct inode *dir, struct inode *inode, + struct htree_lock *lck) { struct dx_frame frames[EXT4_HTREE_LEVEL], *frame; struct dx_entry *entries, *at; @@ -2395,7 +2744,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname, again: restart = 0; - frame = dx_probe(fname, dir, NULL, frames); + frame = dx_probe(fname, dir, NULL, frames, lck); if (IS_ERR(frame)) return PTR_ERR(frame); entries = frame->entries; @@ -2430,6 +2779,12 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname, struct dx_node *node2; struct buffer_head *bh2; + if (!ext4_htree_safe_locked(lck)) { /* retry with EX lock */ + ext4_htree_safe_relock(lck); + restart = 1; + goto cleanup; + } + while (frame > frames) { if (dx_get_count((frame - 1)->entries) < dx_get_limit((frame - 1)->entries)) { @@ -2533,8 +2888,34 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname, restart = 1; goto journal_error; } + } else if (!ext4_htree_dx_locked(lck)) { + struct ext4_dir_lock_data *ld = ext4_htree_lock_data(lck); + + /* not well protected, require DX lock */ + ext4_htree_dx_need_lock(lck); + at = frame > frames ? (frame - 1)->at : NULL; + + /* NB: no risk of deadlock because it's just a try. + * + * NB: we check ld_count for twice, the first time before + * having DX lock, the second time after holding DX lock. + * + * NB: We never free blocks for directory so far, which + * means value returned by dx_get_count() should equal to + * ld->ld_count if nobody split any DE-block under @at, + * and ld->ld_at still points to valid dx_entry. + */ + if ((ld->ld_count != dx_get_count(entries)) || + !ext4_htree_dx_lock_try(lck, at) || + (ld->ld_count != dx_get_count(entries))) { + restart = 1; + goto cleanup; + } + /* OK, I've got DX lock and nothing changed */ + frame->at = ld->ld_at; } - de = do_split(handle, dir, &bh, frame, &fname->hinfo); + + de = do_split(handle, dir, &bh, frames, frame, &fname->hinfo, lck); if (IS_ERR(de)) { err = PTR_ERR(de); goto cleanup; @@ -2545,6 +2926,8 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname, journal_error: ext4_std_error(dir->i_sb, err); /* this is a no-op if err == 0 */ cleanup: + ext4_htree_dx_unlock(lck); + ext4_htree_de_unlock(lck); brelse(bh); dx_release(frames); /* @restart is true means htree-path has been changed, we need to diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 564eb35..07242d7 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1077,6 +1077,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb) return NULL; inode_set_iversion(&ei->vfs_inode, 1); + sema_init(&ei->i_append_sem, 1); spin_lock_init(&ei->i_raw_lock); INIT_LIST_HEAD(&ei->i_prealloc_list); spin_lock_init(&ei->i_prealloc_lock);