2ca99501fa
This fixes a race between the glock and the page lock encountered during truncate in gfs2_readpage and gfs2_prepare_write. The gfs2_readpages function doesn't need the same fix since it only uses a try lock anyway, so it will fail back to gfs2_readpage in the case of a potential deadlock. This bug was spotted by Russell Cattelan. Cc: Russell Cattelan <cattelan@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
152 lines
4.2 KiB
C
152 lines
4.2 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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#ifndef __GLOCK_DOT_H__
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#define __GLOCK_DOT_H__
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#include "incore.h"
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/* Flags for lock requests; used in gfs2_holder gh_flag field.
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From lm_interface.h:
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#define LM_FLAG_TRY 0x00000001
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#define LM_FLAG_TRY_1CB 0x00000002
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#define LM_FLAG_NOEXP 0x00000004
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#define LM_FLAG_ANY 0x00000008
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#define LM_FLAG_PRIORITY 0x00000010 */
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#define GL_LOCAL_EXCL 0x00000020
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#define GL_ASYNC 0x00000040
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#define GL_EXACT 0x00000080
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#define GL_SKIP 0x00000100
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#define GL_ATIME 0x00000200
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#define GL_NOCACHE 0x00000400
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#define GL_NOCANCEL 0x00001000
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#define GLR_TRYFAILED 13
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#define GLR_CANCELED 14
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static inline int gfs2_glock_is_locked_by_me(struct gfs2_glock *gl)
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{
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struct gfs2_holder *gh;
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int locked = 0;
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/* Look in glock's list of holders for one with current task as owner */
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spin_lock(&gl->gl_spin);
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list_for_each_entry(gh, &gl->gl_holders, gh_list) {
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if (gh->gh_owner == current) {
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locked = 1;
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break;
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}
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}
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spin_unlock(&gl->gl_spin);
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return locked;
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}
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static inline int gfs2_glock_is_held_excl(struct gfs2_glock *gl)
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{
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return gl->gl_state == LM_ST_EXCLUSIVE;
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}
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static inline int gfs2_glock_is_held_dfrd(struct gfs2_glock *gl)
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{
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return gl->gl_state == LM_ST_DEFERRED;
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}
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static inline int gfs2_glock_is_held_shrd(struct gfs2_glock *gl)
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{
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return gl->gl_state == LM_ST_SHARED;
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}
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static inline int gfs2_glock_is_blocking(struct gfs2_glock *gl)
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{
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int ret;
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spin_lock(&gl->gl_spin);
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ret = !list_empty(&gl->gl_waiters2) || !list_empty(&gl->gl_waiters3);
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spin_unlock(&gl->gl_spin);
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return ret;
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}
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int gfs2_glock_get(struct gfs2_sbd *sdp,
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u64 number, const struct gfs2_glock_operations *glops,
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int create, struct gfs2_glock **glp);
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void gfs2_glock_hold(struct gfs2_glock *gl);
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int gfs2_glock_put(struct gfs2_glock *gl);
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void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
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struct gfs2_holder *gh);
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void gfs2_holder_reinit(unsigned int state, unsigned flags,
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struct gfs2_holder *gh);
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void gfs2_holder_uninit(struct gfs2_holder *gh);
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void gfs2_glock_xmote_th(struct gfs2_glock *gl, unsigned int state, int flags);
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void gfs2_glock_drop_th(struct gfs2_glock *gl);
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int gfs2_glock_nq(struct gfs2_holder *gh);
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int gfs2_glock_poll(struct gfs2_holder *gh);
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int gfs2_glock_wait(struct gfs2_holder *gh);
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void gfs2_glock_dq(struct gfs2_holder *gh);
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int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time);
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void gfs2_glock_dq_uninit(struct gfs2_holder *gh);
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int gfs2_glock_nq_num(struct gfs2_sbd *sdp,
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u64 number, const struct gfs2_glock_operations *glops,
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unsigned int state, int flags, struct gfs2_holder *gh);
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int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs);
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void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs);
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void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs);
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void gfs2_glock_prefetch_num(struct gfs2_sbd *sdp, u64 number,
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const struct gfs2_glock_operations *glops,
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unsigned int state, int flags);
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void gfs2_glock_inode_squish(struct inode *inode);
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/**
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* gfs2_glock_nq_init - intialize a holder and enqueue it on a glock
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* @gl: the glock
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* @state: the state we're requesting
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* @flags: the modifier flags
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* @gh: the holder structure
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*
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* Returns: 0, GLR_*, or errno
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*/
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static inline int gfs2_glock_nq_init(struct gfs2_glock *gl,
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unsigned int state, int flags,
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struct gfs2_holder *gh)
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{
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int error;
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gfs2_holder_init(gl, state, flags, gh);
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error = gfs2_glock_nq(gh);
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if (error)
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gfs2_holder_uninit(gh);
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return error;
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}
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/* Lock Value Block functions */
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int gfs2_lvb_hold(struct gfs2_glock *gl);
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void gfs2_lvb_unhold(struct gfs2_glock *gl);
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void gfs2_glock_cb(void *cb_data, unsigned int type, void *data);
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void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl);
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void gfs2_reclaim_glock(struct gfs2_sbd *sdp);
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void gfs2_scand_internal(struct gfs2_sbd *sdp);
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void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait);
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int __init gfs2_glock_init(void);
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#endif /* __GLOCK_DOT_H__ */
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