7afd88d916
We've previously been using a "try lock" in readpage on the basis that it would prevent deadlocks due to the inverted lock ordering (our normal lock ordering is glock first and then page lock). Unfortunately tests have shown that this isn't enough. If the glock has a demote request queued such that run_queue() in the glock code tries to do a demote when its called under readpage then it will try and write out all the dirty pages which requires locking them. This then deadlocks with the page locked by readpage. The solution is to always require two calls into readpage. The first unlocks the page, gets the glock and returns AOP_TRUNCATED_PAGE, the second does the actual readpage and unlocks the glock & page as required. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
115 lines
2.4 KiB
C
115 lines
2.4 KiB
C
/*
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* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
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* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License version 2.
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*/
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/completion.h>
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#include <linux/buffer_head.h>
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#include <linux/gfs2_ondisk.h>
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#include <linux/crc32.h>
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#include <linux/lm_interface.h>
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#include "gfs2.h"
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#include "incore.h"
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#include "dir.h"
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#include "glock.h"
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#include "ops_dentry.h"
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#include "util.h"
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#include "inode.h"
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/**
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* gfs2_drevalidate - Check directory lookup consistency
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* @dentry: the mapping to check
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* @nd:
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*
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* Check to make sure the lookup necessary to arrive at this inode from its
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* parent is still good.
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*
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* Returns: 1 if the dentry is ok, 0 if it isn't
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*/
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static int gfs2_drevalidate(struct dentry *dentry, struct nameidata *nd)
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{
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struct dentry *parent = dget_parent(dentry);
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struct gfs2_sbd *sdp = GFS2_SB(parent->d_inode);
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struct gfs2_inode *dip = GFS2_I(parent->d_inode);
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struct inode *inode = dentry->d_inode;
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struct gfs2_holder d_gh;
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struct gfs2_inode *ip = NULL;
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int error;
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int had_lock = 0;
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if (inode) {
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if (is_bad_inode(inode))
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goto invalid;
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ip = GFS2_I(inode);
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}
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if (sdp->sd_args.ar_localcaching)
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goto valid;
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had_lock = (gfs2_glock_is_locked_by_me(dip->i_gl) != NULL);
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if (!had_lock) {
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error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &d_gh);
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if (error)
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goto fail;
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}
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error = gfs2_dir_check(parent->d_inode, &dentry->d_name, ip);
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switch (error) {
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case 0:
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if (!inode)
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goto invalid_gunlock;
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break;
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case -ENOENT:
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if (!inode)
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goto valid_gunlock;
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goto invalid_gunlock;
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default:
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goto fail_gunlock;
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}
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valid_gunlock:
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if (!had_lock)
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gfs2_glock_dq_uninit(&d_gh);
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valid:
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dput(parent);
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return 1;
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invalid_gunlock:
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if (!had_lock)
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gfs2_glock_dq_uninit(&d_gh);
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invalid:
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if (inode && S_ISDIR(inode->i_mode)) {
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if (have_submounts(dentry))
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goto valid;
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shrink_dcache_parent(dentry);
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}
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d_drop(dentry);
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dput(parent);
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return 0;
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fail_gunlock:
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gfs2_glock_dq_uninit(&d_gh);
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fail:
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dput(parent);
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return 0;
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}
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static int gfs2_dhash(struct dentry *dentry, struct qstr *str)
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{
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str->hash = gfs2_disk_hash(str->name, str->len);
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return 0;
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}
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struct dentry_operations gfs2_dops = {
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.d_revalidate = gfs2_drevalidate,
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.d_hash = gfs2_dhash,
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};
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