diff options
Diffstat (limited to 'fs/ocfs2/dcache.c')
-rw-r--r-- | fs/ocfs2/dcache.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c new file mode 100644 index 000000000..42a61eecd --- /dev/null +++ b/fs/ocfs2/dcache.c @@ -0,0 +1,472 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* -*- mode: c; c-basic-offset: 8; -*- + * vim: noexpandtab sw=8 ts=8 sts=0: + * + * dcache.c + * + * dentry cache handling code + * + * Copyright (C) 2002, 2004 Oracle. All rights reserved. + */ + +#include <linux/fs.h> +#include <linux/types.h> +#include <linux/slab.h> +#include <linux/namei.h> + +#include <cluster/masklog.h> + +#include "ocfs2.h" + +#include "alloc.h" +#include "dcache.h" +#include "dlmglue.h" +#include "file.h" +#include "inode.h" +#include "ocfs2_trace.h" + +void ocfs2_dentry_attach_gen(struct dentry *dentry) +{ + unsigned long gen = + OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen; + BUG_ON(d_inode(dentry)); + dentry->d_fsdata = (void *)gen; +} + + +static int ocfs2_dentry_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct inode *inode; + int ret = 0; /* if all else fails, just return false */ + struct ocfs2_super *osb; + + if (flags & LOOKUP_RCU) + return -ECHILD; + + inode = d_inode(dentry); + osb = OCFS2_SB(dentry->d_sb); + + trace_ocfs2_dentry_revalidate(dentry, dentry->d_name.len, + dentry->d_name.name); + + /* For a negative dentry - + * check the generation number of the parent and compare with the + * one stored in the inode. + */ + if (inode == NULL) { + unsigned long gen = (unsigned long) dentry->d_fsdata; + unsigned long pgen; + spin_lock(&dentry->d_lock); + pgen = OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen; + spin_unlock(&dentry->d_lock); + trace_ocfs2_dentry_revalidate_negative(dentry->d_name.len, + dentry->d_name.name, + pgen, gen); + if (gen != pgen) + goto bail; + goto valid; + } + + BUG_ON(!osb); + + if (inode == osb->root_inode || is_bad_inode(inode)) + goto bail; + + spin_lock(&OCFS2_I(inode)->ip_lock); + /* did we or someone else delete this inode? */ + if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) { + spin_unlock(&OCFS2_I(inode)->ip_lock); + trace_ocfs2_dentry_revalidate_delete( + (unsigned long long)OCFS2_I(inode)->ip_blkno); + goto bail; + } + spin_unlock(&OCFS2_I(inode)->ip_lock); + + /* + * We don't need a cluster lock to test this because once an + * inode nlink hits zero, it never goes back. + */ + if (inode->i_nlink == 0) { + trace_ocfs2_dentry_revalidate_orphaned( + (unsigned long long)OCFS2_I(inode)->ip_blkno, + S_ISDIR(inode->i_mode)); + goto bail; + } + + /* + * If the last lookup failed to create dentry lock, let us + * redo it. + */ + if (!dentry->d_fsdata) { + trace_ocfs2_dentry_revalidate_nofsdata( + (unsigned long long)OCFS2_I(inode)->ip_blkno); + goto bail; + } + +valid: + ret = 1; + +bail: + trace_ocfs2_dentry_revalidate_ret(ret); + return ret; +} + +static int ocfs2_match_dentry(struct dentry *dentry, + u64 parent_blkno, + int skip_unhashed) +{ + struct inode *parent; + + /* + * ocfs2_lookup() does a d_splice_alias() _before_ attaching + * to the lock data, so we skip those here, otherwise + * ocfs2_dentry_attach_lock() will get its original dentry + * back. + */ + if (!dentry->d_fsdata) + return 0; + + if (!dentry->d_parent) + return 0; + + if (skip_unhashed && d_unhashed(dentry)) + return 0; + + parent = d_inode(dentry->d_parent); + /* Negative parent dentry? */ + if (!parent) + return 0; + + /* Name is in a different directory. */ + if (OCFS2_I(parent)->ip_blkno != parent_blkno) + return 0; + + return 1; +} + +/* + * Walk the inode alias list, and find a dentry which has a given + * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it + * is looking for a dentry_lock reference. The downconvert thread is + * looking to unhash aliases, so we allow it to skip any that already + * have that property. + */ +struct dentry *ocfs2_find_local_alias(struct inode *inode, + u64 parent_blkno, + int skip_unhashed) +{ + struct dentry *dentry; + + spin_lock(&inode->i_lock); + hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { + spin_lock(&dentry->d_lock); + if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) { + trace_ocfs2_find_local_alias(dentry->d_name.len, + dentry->d_name.name); + + dget_dlock(dentry); + spin_unlock(&dentry->d_lock); + spin_unlock(&inode->i_lock); + return dentry; + } + spin_unlock(&dentry->d_lock); + } + spin_unlock(&inode->i_lock); + return NULL; +} + +DEFINE_SPINLOCK(dentry_attach_lock); + +/* + * Attach this dentry to a cluster lock. + * + * Dentry locks cover all links in a given directory to a particular + * inode. We do this so that ocfs2 can build a lock name which all + * nodes in the cluster can agree on at all times. Shoving full names + * in the cluster lock won't work due to size restrictions. Covering + * links inside of a directory is a good compromise because it still + * allows us to use the parent directory lock to synchronize + * operations. + * + * Call this function with the parent dir semaphore and the parent dir + * cluster lock held. + * + * The dir semaphore will protect us from having to worry about + * concurrent processes on our node trying to attach a lock at the + * same time. + * + * The dir cluster lock (held at either PR or EX mode) protects us + * from unlink and rename on other nodes. + * + * A dput() can happen asynchronously due to pruning, so we cover + * attaching and detaching the dentry lock with a + * dentry_attach_lock. + * + * A node which has done lookup on a name retains a protected read + * lock until final dput. If the user requests and unlink or rename, + * the protected read is upgraded to an exclusive lock. Other nodes + * who have seen the dentry will then be informed that they need to + * downgrade their lock, which will involve d_delete on the + * dentry. This happens in ocfs2_dentry_convert_worker(). + */ +int ocfs2_dentry_attach_lock(struct dentry *dentry, + struct inode *inode, + u64 parent_blkno) +{ + int ret; + struct dentry *alias; + struct ocfs2_dentry_lock *dl = dentry->d_fsdata; + + trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name, + (unsigned long long)parent_blkno, dl); + + /* + * Negative dentry. We ignore these for now. + * + * XXX: Could we can improve ocfs2_dentry_revalidate() by + * tracking these? + */ + if (!inode) + return 0; + + if (d_really_is_negative(dentry) && dentry->d_fsdata) { + /* Converting a negative dentry to positive + Clear dentry->d_fsdata */ + dentry->d_fsdata = dl = NULL; + } + + if (dl) { + mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, + " \"%pd\": old parent: %llu, new: %llu\n", + dentry, + (unsigned long long)parent_blkno, + (unsigned long long)dl->dl_parent_blkno); + return 0; + } + + alias = ocfs2_find_local_alias(inode, parent_blkno, 0); + if (alias) { + /* + * Great, an alias exists, which means we must have a + * dentry lock already. We can just grab the lock off + * the alias and add it to the list. + * + * We're depending here on the fact that this dentry + * was found and exists in the dcache and so must have + * a reference to the dentry_lock because we can't + * race creates. Final dput() cannot happen on it + * since we have it pinned, so our reference is safe. + */ + dl = alias->d_fsdata; + mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n", + (unsigned long long)parent_blkno, + (unsigned long long)OCFS2_I(inode)->ip_blkno); + + mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, + " \"%pd\": old parent: %llu, new: %llu\n", + dentry, + (unsigned long long)parent_blkno, + (unsigned long long)dl->dl_parent_blkno); + + trace_ocfs2_dentry_attach_lock_found(dl->dl_lockres.l_name, + (unsigned long long)parent_blkno, + (unsigned long long)OCFS2_I(inode)->ip_blkno); + + goto out_attach; + } + + /* + * There are no other aliases + */ + dl = kmalloc(sizeof(*dl), GFP_NOFS); + if (!dl) { + ret = -ENOMEM; + mlog_errno(ret); + return ret; + } + + dl->dl_count = 0; + /* + * Does this have to happen below, for all attaches, in case + * the struct inode gets blown away by the downconvert thread? + */ + dl->dl_inode = igrab(inode); + dl->dl_parent_blkno = parent_blkno; + ocfs2_dentry_lock_res_init(dl, parent_blkno, inode); + +out_attach: + spin_lock(&dentry_attach_lock); + if (unlikely(dentry->d_fsdata && !alias)) { + /* d_fsdata is set by a racing thread which is doing + * the same thing as this thread is doing. Leave the racing + * thread going ahead and we return here. + */ + spin_unlock(&dentry_attach_lock); + iput(dl->dl_inode); + ocfs2_lock_res_free(&dl->dl_lockres); + kfree(dl); + return 0; + } + + dentry->d_fsdata = dl; + dl->dl_count++; + spin_unlock(&dentry_attach_lock); + + /* + * This actually gets us our PRMODE level lock. From now on, + * we'll have a notification if one of these names is + * destroyed on another node. + */ + ret = ocfs2_dentry_lock(dentry, 0); + if (!ret) + ocfs2_dentry_unlock(dentry, 0); + else + mlog_errno(ret); + + /* + * In case of error, manually free the allocation and do the iput(). + * We need to do this because error here means no d_instantiate(), + * which means iput() will not be called during dput(dentry). + */ + if (ret < 0 && !alias) { + ocfs2_lock_res_free(&dl->dl_lockres); + BUG_ON(dl->dl_count != 1); + spin_lock(&dentry_attach_lock); + dentry->d_fsdata = NULL; + spin_unlock(&dentry_attach_lock); + kfree(dl); + iput(inode); + } + + dput(alias); + + return ret; +} + +/* + * ocfs2_dentry_iput() and friends. + * + * At this point, our particular dentry is detached from the inodes + * alias list, so there's no way that the locking code can find it. + * + * The interesting stuff happens when we determine that our lock needs + * to go away because this is the last subdir alias in the + * system. This function needs to handle a couple things: + * + * 1) Synchronizing lock shutdown with the downconvert threads. This + * is already handled for us via the lockres release drop function + * called in ocfs2_release_dentry_lock() + * + * 2) A race may occur when we're doing our lock shutdown and + * another process wants to create a new dentry lock. Right now we + * let them race, which means that for a very short while, this + * node might have two locks on a lock resource. This should be a + * problem though because one of them is in the process of being + * thrown out. + */ +static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb, + struct ocfs2_dentry_lock *dl) +{ + iput(dl->dl_inode); + ocfs2_simple_drop_lockres(osb, &dl->dl_lockres); + ocfs2_lock_res_free(&dl->dl_lockres); + kfree(dl); +} + +void ocfs2_dentry_lock_put(struct ocfs2_super *osb, + struct ocfs2_dentry_lock *dl) +{ + int unlock = 0; + + BUG_ON(dl->dl_count == 0); + + spin_lock(&dentry_attach_lock); + dl->dl_count--; + unlock = !dl->dl_count; + spin_unlock(&dentry_attach_lock); + + if (unlock) + ocfs2_drop_dentry_lock(osb, dl); +} + +static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode) +{ + struct ocfs2_dentry_lock *dl = dentry->d_fsdata; + + if (!dl) { + /* + * No dentry lock is ok if we're disconnected or + * unhashed. + */ + if (!(dentry->d_flags & DCACHE_DISCONNECTED) && + !d_unhashed(dentry)) { + unsigned long long ino = 0ULL; + if (inode) + ino = (unsigned long long)OCFS2_I(inode)->ip_blkno; + mlog(ML_ERROR, "Dentry is missing cluster lock. " + "inode: %llu, d_flags: 0x%x, d_name: %pd\n", + ino, dentry->d_flags, dentry); + } + + goto out; + } + + mlog_bug_on_msg(dl->dl_count == 0, "dentry: %pd, count: %u\n", + dentry, dl->dl_count); + + ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl); + +out: + iput(inode); +} + +/* + * d_move(), but keep the locks in sync. + * + * When we are done, "dentry" will have the parent dir and name of + * "target", which will be thrown away. + * + * We manually update the lock of "dentry" if need be. + * + * "target" doesn't have it's dentry lock touched - we allow the later + * dput() to handle this for us. + * + * This is called during ocfs2_rename(), while holding parent + * directory locks. The dentries have already been deleted on other + * nodes via ocfs2_remote_dentry_delete(). + * + * Normally, the VFS handles the d_move() for the file system, after + * the ->rename() callback. OCFS2 wants to handle this internally, so + * the new lock can be created atomically with respect to the cluster. + */ +void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target, + struct inode *old_dir, struct inode *new_dir) +{ + int ret; + struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb); + struct inode *inode = d_inode(dentry); + + /* + * Move within the same directory, so the actual lock info won't + * change. + * + * XXX: Is there any advantage to dropping the lock here? + */ + if (old_dir == new_dir) + goto out_move; + + ocfs2_dentry_lock_put(osb, dentry->d_fsdata); + + dentry->d_fsdata = NULL; + ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno); + if (ret) + mlog_errno(ret); + +out_move: + d_move(dentry, target); +} + +const struct dentry_operations ocfs2_dentry_ops = { + .d_revalidate = ocfs2_dentry_revalidate, + .d_iput = ocfs2_dentry_iput, +}; |