/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/quotaops.h>

#define DEBUG_SUBSYSTEM S_LLITE

#include <obd_support.h>
#include <lustre_lite.h>
#include <lustre/lustre_idl.h>
#include <lustre_dlm.h>

#include "llite_internal.h"

static void free_dentry_data(struct rcu_head *head)
{
	struct ll_dentry_data *lld;

	lld = container_of(head, struct ll_dentry_data, lld_rcu_head);
	OBD_FREE_PTR(lld);
}

/* should NOT be called with the dcache lock, see fs/dcache.c */
static void ll_release(struct dentry *de)
{
	struct ll_dentry_data *lld;

	LASSERT(de != NULL);
	lld = ll_d2d(de);
	if (lld == NULL) /* NFS copies the de->d_op methods (bug 4655) */
		return;

	if (lld->lld_it) {
		ll_intent_release(lld->lld_it);
		OBD_FREE(lld->lld_it, sizeof(*lld->lld_it));
	}
	LASSERT(lld->lld_cwd_count == 0);
	LASSERT(lld->lld_mnt_count == 0);
	de->d_fsdata = NULL;
	call_rcu(&lld->lld_rcu_head, free_dentry_data);
}

/* Compare if two dentries are the same.  Don't match if the existing dentry
 * is marked invalid.  Returns 1 if different, 0 if the same.
 *
 * This avoids a race where ll_lookup_it() instantiates a dentry, but we get
 * an AST before calling d_revalidate_it().  The dentry still exists (marked
 * INVALID) so d_lookup() matches it, but we have no lock on it (so
 * lock_match() fails) and we spin around real_lookup(). */
int ll_dcompare(const struct dentry *parent, const struct dentry *dentry,
		unsigned int len, const char *str, const struct qstr *name)
{
	if (len != name->len)
		return 1;

	if (memcmp(str, name->name, len))
		return 1;

	CDEBUG(D_DENTRY, "found name %.*s(%p) flags %#x refc %d\n",
	       name->len, name->name, dentry, dentry->d_flags,
	       d_count(dentry));

	/* mountpoint is always valid */
	if (d_mountpoint((struct dentry *)dentry))
		return 0;

	if (d_lustre_invalid(dentry))
		return 1;

	return 0;
}

static inline int return_if_equal(struct ldlm_lock *lock, void *data)
{
	if ((lock->l_flags &
	     (LDLM_FL_CANCELING | LDLM_FL_DISCARD_DATA)) ==
	    (LDLM_FL_CANCELING | LDLM_FL_DISCARD_DATA))
		return LDLM_ITER_CONTINUE;
	return LDLM_ITER_STOP;
}

/* find any ldlm lock of the inode in mdc and lov
 * return 0    not find
 *	1    find one
 *      < 0    error */
static int find_cbdata(struct inode *inode)
{
	struct ll_sb_info *sbi = ll_i2sbi(inode);
	struct lov_stripe_md *lsm;
	int rc = 0;

	LASSERT(inode);
	rc = md_find_cbdata(sbi->ll_md_exp, ll_inode2fid(inode),
			    return_if_equal, NULL);
	if (rc != 0)
		 return rc;

	lsm = ccc_inode_lsm_get(inode);
	if (lsm == NULL)
		return rc;

	rc = obd_find_cbdata(sbi->ll_dt_exp, lsm, return_if_equal, NULL);
	ccc_inode_lsm_put(inode, lsm);

	return rc;
}

/**
 * Called when last reference to a dentry is dropped and dcache wants to know
 * whether or not it should cache it:
 * - return 1 to delete the dentry immediately
 * - return 0 to cache the dentry
 * Should NOT be called with the dcache lock, see fs/dcache.c
 */
static int ll_ddelete(const struct dentry *de)
{
	LASSERT(de);

	CDEBUG(D_DENTRY, "%s dentry %.*s (%p, parent %p, inode %p) %s%s\n",
	       d_lustre_invalid((struct dentry *)de) ? "deleting" : "keeping",
	       de->d_name.len, de->d_name.name, de, de->d_parent, de->d_inode,
	       d_unhashed((struct dentry *)de) ? "" : "hashed,",
	       list_empty(&de->d_subdirs) ? "" : "subdirs");

	/* kernel >= 2.6.38 last refcount is decreased after this function. */
	LASSERT(d_count(de) == 1);

	/* Disable this piece of code temproarily because this is called
	 * inside dcache_lock so it's not appropriate to do lots of work
	 * here. ATTENTION: Before this piece of code enabling, LU-2487 must be
	 * resolved. */
#if 0
	/* if not ldlm lock for this inode, set i_nlink to 0 so that
	 * this inode can be recycled later b=20433 */
	if (de->d_inode && !find_cbdata(de->d_inode))
		clear_nlink(de->d_inode);
#endif

	if (d_lustre_invalid((struct dentry *)de))
		return 1;
	return 0;
}

static int ll_set_dd(struct dentry *de)
{
	LASSERT(de != NULL);

	CDEBUG(D_DENTRY, "ldd on dentry %.*s (%p) parent %p inode %p refc %d\n",
		de->d_name.len, de->d_name.name, de, de->d_parent, de->d_inode,
		d_count(de));

	if (de->d_fsdata == NULL) {
		struct ll_dentry_data *lld;

		OBD_ALLOC_PTR(lld);
		if (likely(lld != NULL)) {
			spin_lock(&de->d_lock);
			if (likely(de->d_fsdata == NULL))
				de->d_fsdata = lld;
			else
				OBD_FREE_PTR(lld);
			spin_unlock(&de->d_lock);
		} else {
			return -ENOMEM;
		}
	}

	return 0;
}

int ll_dops_init(struct dentry *de, int block, int init_sa)
{
	struct ll_dentry_data *lld = ll_d2d(de);
	int rc = 0;

	if (lld == NULL && block != 0) {
		rc = ll_set_dd(de);
		if (rc)
			return rc;

		lld = ll_d2d(de);
	}

	if (lld != NULL && init_sa != 0)
		lld->lld_sa_generation = 0;

	/* kernel >= 2.6.38 d_op is set in d_alloc() */
	LASSERT(de->d_op == &ll_d_ops);
	return rc;
}

void ll_intent_drop_lock(struct lookup_intent *it)
{
	if (it->it_op && it->d.lustre.it_lock_mode) {
		struct lustre_handle handle;

		handle.cookie = it->d.lustre.it_lock_handle;

		CDEBUG(D_DLMTRACE, "releasing lock with cookie "LPX64
		       " from it %p\n", handle.cookie, it);
		ldlm_lock_decref(&handle, it->d.lustre.it_lock_mode);

		/* bug 494: intent_release may be called multiple times, from
		 * this thread and we don't want to double-decref this lock */
		it->d.lustre.it_lock_mode = 0;
		if (it->d.lustre.it_remote_lock_mode != 0) {
			handle.cookie = it->d.lustre.it_remote_lock_handle;

			CDEBUG(D_DLMTRACE, "releasing remote lock with cookie"
			       LPX64" from it %p\n", handle.cookie, it);
			ldlm_lock_decref(&handle,
					 it->d.lustre.it_remote_lock_mode);
			it->d.lustre.it_remote_lock_mode = 0;
		}
	}
}

void ll_intent_release(struct lookup_intent *it)
{
	CDEBUG(D_INFO, "intent %p released\n", it);
	ll_intent_drop_lock(it);
	/* We are still holding extra reference on a request, need to free it */
	if (it_disposition(it, DISP_ENQ_OPEN_REF))
		 ptlrpc_req_finished(it->d.lustre.it_data); /* ll_file_open */
	if (it_disposition(it, DISP_ENQ_CREATE_REF)) /* create rec */
		ptlrpc_req_finished(it->d.lustre.it_data);
	if (it_disposition(it, DISP_ENQ_COMPLETE)) /* saved req from revalidate
						    * to lookup */
		ptlrpc_req_finished(it->d.lustre.it_data);

	it->d.lustre.it_disposition = 0;
	it->d.lustre.it_data = NULL;
}

void ll_invalidate_aliases(struct inode *inode)
{
	struct dentry *dentry;
	struct ll_d_hlist_node *p;

	LASSERT(inode != NULL);

	CDEBUG(D_INODE, "marking dentries for ino %lu/%u(%p) invalid\n",
	       inode->i_ino, inode->i_generation, inode);

	ll_lock_dcache(inode);
	ll_d_hlist_for_each_entry(dentry, p, &inode->i_dentry, d_alias) {
		CDEBUG(D_DENTRY, "dentry in drop %.*s (%p) parent %p "
		       "inode %p flags %d\n", dentry->d_name.len,
		       dentry->d_name.name, dentry, dentry->d_parent,
		       dentry->d_inode, dentry->d_flags);

		if (unlikely(dentry == dentry->d_sb->s_root)) {
			CERROR("%s: called on root dentry=%p, fid="DFID"\n",
			       ll_get_fsname(dentry->d_sb, NULL, 0),
			       dentry, PFID(ll_inode2fid(inode)));
			lustre_dump_dentry(dentry, 1);
			dump_stack();
		}

		d_lustre_invalidate(dentry, 0);
	}
	ll_unlock_dcache(inode);
}

int ll_revalidate_it_finish(struct ptlrpc_request *request,
			    struct lookup_intent *it,
			    struct dentry *de)
{
	int rc = 0;

	if (!request)
		return 0;

	if (it_disposition(it, DISP_LOOKUP_NEG))
		return -ENOENT;

	rc = ll_prep_inode(&de->d_inode, request, NULL, it);

	return rc;
}

void ll_lookup_finish_locks(struct lookup_intent *it, struct dentry *dentry)
{
	LASSERT(it != NULL);
	LASSERT(dentry != NULL);

	if (it->d.lustre.it_lock_mode && dentry->d_inode != NULL) {
		struct inode *inode = dentry->d_inode;
		struct ll_sb_info *sbi = ll_i2sbi(dentry->d_inode);

		CDEBUG(D_DLMTRACE, "setting l_data to inode %p (%lu/%u)\n",
		       inode, inode->i_ino, inode->i_generation);
		ll_set_lock_data(sbi->ll_md_exp, inode, it, NULL);
	}

	/* drop lookup or getattr locks immediately */
	if (it->it_op == IT_LOOKUP || it->it_op == IT_GETATTR) {
		/* on 2.6 there are situation when several lookups and
		 * revalidations may be requested during single operation.
		 * therefore, we don't release intent here -bzzz */
		ll_intent_drop_lock(it);
	}
}

void ll_frob_intent(struct lookup_intent **itp, struct lookup_intent *deft)
{
	struct lookup_intent *it = *itp;

	if (!it || it->it_op == IT_GETXATTR)
		it = *itp = deft;

}

int ll_revalidate_it(struct dentry *de, int lookup_flags,
		     struct lookup_intent *it)
{
	struct md_op_data *op_data;
	struct ptlrpc_request *req = NULL;
	struct lookup_intent lookup_it = { .it_op = IT_LOOKUP };
	struct obd_export *exp;
	struct inode *parent = de->d_parent->d_inode;
	int rc;

	CDEBUG(D_VFSTRACE, "VFS Op:name=%s,intent=%s\n", de->d_name.name,
	       LL_IT2STR(it));

	if (de->d_inode == NULL) {
		__u64 ibits;

		/* We can only use negative dentries if this is stat or lookup,
		   for opens and stuff we do need to query server. */
		/* If there is IT_CREAT in intent op set, then we must throw
		   away this negative dentry and actually do the request to
		   kernel to create whatever needs to be created (if possible)*/
		if (it && (it->it_op & IT_CREAT))
			return 0;

		if (d_lustre_invalid(de))
			return 0;

		ibits = MDS_INODELOCK_UPDATE;
		rc = ll_have_md_lock(parent, &ibits, LCK_MINMODE);
		GOTO(out_sa, rc);
	}

	/* Never execute intents for mount points.
	 * Attributes will be fixed up in ll_inode_revalidate_it */
	if (d_mountpoint(de))
		GOTO(out_sa, rc = 1);

	/* need to get attributes in case root got changed from other client */
	if (de == de->d_sb->s_root) {
		rc = __ll_inode_revalidate_it(de, it, MDS_INODELOCK_LOOKUP);
		if (rc == 0)
			rc = 1;
		GOTO(out_sa, rc);
	}

	exp = ll_i2mdexp(de->d_inode);

	OBD_FAIL_TIMEOUT(OBD_FAIL_MDC_REVALIDATE_PAUSE, 5);
	ll_frob_intent(&it, &lookup_it);
	LASSERT(it);

	if (it->it_op == IT_LOOKUP && !d_lustre_invalid(de))
		return 1;

	if (it->it_op == IT_OPEN) {
		struct inode *inode = de->d_inode;
		struct ll_inode_info *lli = ll_i2info(inode);
		struct obd_client_handle **och_p;
		__u64 ibits;

		/*
		 * We used to check for MDS_INODELOCK_OPEN here, but in fact
		 * just having LOOKUP lock is enough to justify inode is the
		 * same. And if inode is the same and we have suitable
		 * openhandle, then there is no point in doing another OPEN RPC
		 * just to throw away newly received openhandle.  There are no
		 * security implications too, if file owner or access mode is
		 * change, LOOKUP lock is revoked.
		 */


		if (it->it_flags & FMODE_WRITE)
			och_p = &lli->lli_mds_write_och;
		else if (it->it_flags & FMODE_EXEC)
			och_p = &lli->lli_mds_exec_och;
		else
			och_p = &lli->lli_mds_read_och;

		/* Check for the proper lock. */
		ibits = MDS_INODELOCK_LOOKUP;
		if (!ll_have_md_lock(inode, &ibits, LCK_MINMODE))
			goto do_lock;
		mutex_lock(&lli->lli_och_mutex);
		if (*och_p) { /* Everything is open already, do nothing */
			/* Originally it was idea to do not let them steal our
			 * open handle from under us by (*och_usecount)++ here.
			 * But in case we have the handle, but we cannot use it
			 * due to later checks (e.g. O_CREAT|O_EXCL flags set),
			 * nobody would decrement counter increased here. So we
			 * just hope the lock won't be invalidated in between.
			 * But if it would be, we'll reopen the open request to
			 * MDS later during file open path.
			 */
			mutex_unlock(&lli->lli_och_mutex);
			return 1;
		}
		mutex_unlock(&lli->lli_och_mutex);
	}

	if (it->it_op == IT_GETATTR) {
		rc = ll_statahead_enter(parent, &de, 0);
		if (rc == 1)
			goto mark;
		else if (rc != -EAGAIN && rc != 0)
			GOTO(out, rc = 0);
	}

do_lock:
	op_data = ll_prep_md_op_data(NULL, parent, de->d_inode,
				     de->d_name.name, de->d_name.len,
				     0, LUSTRE_OPC_ANY, NULL);
	if (IS_ERR(op_data))
		return PTR_ERR(op_data);

	if (!IS_POSIXACL(parent) || !exp_connect_umask(exp))
		it->it_create_mode &= ~current_umask();
	it->it_create_mode |= M_CHECK_STALE;
	rc = md_intent_lock(exp, op_data, NULL, 0, it,
			    lookup_flags,
			    &req, ll_md_blocking_ast, 0);
	it->it_create_mode &= ~M_CHECK_STALE;
	ll_finish_md_op_data(op_data);

	/* If req is NULL, then md_intent_lock only tried to do a lock match;
	 * if all was well, it will return 1 if it found locks, 0 otherwise. */
	if (req == NULL && rc >= 0) {
		if (!rc)
			goto do_lookup;
		GOTO(out, rc);
	}

	if (rc < 0) {
		if (rc != -ESTALE) {
			CDEBUG(D_INFO, "ll_intent_lock: rc %d : it->it_status "
			       "%d\n", rc, it->d.lustre.it_status);
		}
		GOTO(out, rc = 0);
	}

revalidate_finish:
	rc = ll_revalidate_it_finish(req, it, de);
	if (rc != 0) {
		if (rc != -ESTALE && rc != -ENOENT)
			ll_intent_release(it);
		GOTO(out, rc = 0);
	}

	if ((it->it_op & IT_OPEN) && de->d_inode &&
	    !S_ISREG(de->d_inode->i_mode) &&
	    !S_ISDIR(de->d_inode->i_mode)) {
		ll_release_openhandle(de, it);
	}
	rc = 1;

out:
	/* We do not free request as it may be reused during following lookup
	 * (see comment in mdc/mdc_locks.c::mdc_intent_lock()), request will
	 * be freed in ll_lookup_it or in ll_intent_release. But if
	 * request was not completed, we need to free it. (bug 5154, 9903) */
	if (req != NULL && !it_disposition(it, DISP_ENQ_COMPLETE))
		ptlrpc_req_finished(req);
	if (rc == 0) {
		/* mdt may grant layout lock for the newly created file, so
		 * release the lock to avoid leaking */
		ll_intent_drop_lock(it);
		ll_invalidate_aliases(de->d_inode);
	} else {
		__u64 bits = 0;
		__u64 matched_bits = 0;

		CDEBUG(D_DENTRY, "revalidated dentry %.*s (%p) parent %p "
		       "inode %p refc %d\n", de->d_name.len,
		       de->d_name.name, de, de->d_parent, de->d_inode,
		       d_count(de));

		ll_set_lock_data(exp, de->d_inode, it, &bits);

		/* Note: We have to match both LOOKUP and PERM lock
		 * here to make sure the dentry is valid and no one
		 * changing the permission.
		 * But if the client connects < 2.4 server, which will
		 * only grant LOOKUP lock, so we can only Match LOOKUP
		 * lock for old server */
		if (exp_connect_flags(ll_i2mdexp(de->d_inode)) &&
							OBD_CONNECT_LVB_TYPE)
			matched_bits =
				MDS_INODELOCK_LOOKUP | MDS_INODELOCK_PERM;
		else
			matched_bits = MDS_INODELOCK_LOOKUP;

		if (((bits & matched_bits) == matched_bits) &&
		    d_lustre_invalid(de))
			d_lustre_revalidate(de);
		ll_lookup_finish_locks(it, de);
	}

mark:
	if (it != NULL && it->it_op == IT_GETATTR && rc > 0)
		ll_statahead_mark(parent, de);
	return rc;

	/*
	 * This part is here to combat evil-evil race in real_lookup on 2.6
	 * kernels.  The race details are: We enter do_lookup() looking for some
	 * name, there is nothing in dcache for this name yet and d_lookup()
	 * returns NULL.  We proceed to real_lookup(), and while we do this,
	 * another process does open on the same file we looking up (most simple
	 * reproducer), open succeeds and the dentry is added. Now back to
	 * us. In real_lookup() we do d_lookup() again and suddenly find the
	 * dentry, so we call d_revalidate on it, but there is no lock, so
	 * without this code we would return 0, but unpatched real_lookup just
	 * returns -ENOENT in such a case instead of retrying the lookup. Once
	 * this is dealt with in real_lookup(), all of this ugly mess can go and
	 * we can just check locks in ->d_revalidate without doing any RPCs
	 * ever.
	 */
do_lookup:
	if (it != &lookup_it) {
		/* MDS_INODELOCK_UPDATE needed for IT_GETATTR case. */
		if (it->it_op == IT_GETATTR)
			lookup_it.it_op = IT_GETATTR;
		ll_lookup_finish_locks(it, de);
		it = &lookup_it;
	}

	/* Do real lookup here. */
	op_data = ll_prep_md_op_data(NULL, parent, NULL, de->d_name.name,
				     de->d_name.len, 0, (it->it_op & IT_CREAT ?
							 LUSTRE_OPC_CREATE :
							 LUSTRE_OPC_ANY), NULL);
	if (IS_ERR(op_data))
		return PTR_ERR(op_data);

	rc = md_intent_lock(exp, op_data, NULL, 0,  it, 0, &req,
			    ll_md_blocking_ast, 0);
	if (rc >= 0) {
		struct mdt_body *mdt_body;
		struct lu_fid fid = {.f_seq = 0, .f_oid = 0, .f_ver = 0};
		mdt_body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);

		if (de->d_inode)
			fid = *ll_inode2fid(de->d_inode);

		/* see if we got same inode, if not - return error */
		if (lu_fid_eq(&fid, &mdt_body->fid1)) {
			ll_finish_md_op_data(op_data);
			op_data = NULL;
			goto revalidate_finish;
		}
		ll_intent_release(it);
	}
	ll_finish_md_op_data(op_data);
	GOTO(out, rc = 0);

out_sa:
	/*
	 * For rc == 1 case, should not return directly to prevent losing
	 * statahead windows; for rc == 0 case, the "lookup" will be done later.
	 */
	if (it != NULL && it->it_op == IT_GETATTR && rc == 1)
		ll_statahead_enter(parent, &de, 1);
	goto mark;
}

/*
 * Always trust cached dentries. Update statahead window if necessary.
 */
int ll_revalidate_nd(struct dentry *dentry, unsigned int flags)
{
	struct inode *parent = dentry->d_parent->d_inode;
	int unplug = 0;

	CDEBUG(D_VFSTRACE, "VFS Op:name=%s,flags=%u\n",
	       dentry->d_name.name, flags);

	if (!(flags & (LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE)) &&
	    ll_need_statahead(parent, dentry) > 0) {
		if (flags & LOOKUP_RCU)
			return -ECHILD;

		if (dentry->d_inode == NULL)
			unplug = 1;
		do_statahead_enter(parent, &dentry, unplug);
		ll_statahead_mark(parent, dentry);
	}

	return 1;
}


void ll_d_iput(struct dentry *de, struct inode *inode)
{
	LASSERT(inode);
	if (!find_cbdata(inode))
		clear_nlink(inode);
	iput(inode);
}

struct dentry_operations ll_d_ops = {
	.d_revalidate = ll_revalidate_nd,
	.d_release = ll_release,
	.d_delete  = ll_ddelete,
	.d_iput    = ll_d_iput,
	.d_compare = ll_dcompare,
};