/*
- * Copyright (c) 2002-2005 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2002-2014 Apple Inc. All rights reserved.
*
- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License"). You may not use this file except in compliance with the
- * License. Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
*
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
*
- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#ifndef _HFS_CNODE_H_
#define _HFS_CNODE_H_
#ifdef KERNEL
#ifdef __APPLE_API_PRIVATE
+#include <stdbool.h>
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <hfs/hfs_catalog.h>
#include <hfs/rangelist.h>
-
+#if HFS_COMPRESSION
+#include <sys/decmpfs.h>
+#endif
+#if CONFIG_PROTECT
+#include <sys/cprotect.h>
+#endif
+#include <kern/assert.h>
/*
* The filefork is used to represent an HFS file fork (data or resource).
};
typedef struct filefork filefork_t;
+
+#define HFS_TEMPLOOKUP_NAMELEN 32
+
+/*
+ * Catalog Lookup struct (runtime)
+ *
+ * This is used so that when we need to malloc a container for a catalog
+ * lookup operation, we can acquire memory for everything in one fell swoop
+ * as opposed to putting many of these objects on the stack. The cat_fork
+ * data structure can take up 100+bytes easily, and that can add to stack
+ * overhead.
+ *
+ * As a result, we use this to easily pass around the memory needed for a
+ * lookup operation.
+ */
+struct cat_lookup_buffer {
+ struct cat_desc lookup_desc;
+ struct cat_attr lookup_attr;
+ struct filefork lookup_fork;
+ struct componentname lookup_cn;
+ char lookup_name[HFS_TEMPLOOKUP_NAMELEN]; /* for open-unlinked paths only */
+};
+
+
/* Aliases for common fields */
#define ff_size ff_data.cf_size
+#define ff_new_size ff_data.cf_new_size
#define ff_clumpsize ff_data.cf_clump
#define ff_bytesread ff_data.cf_bytesread
-#define ff_blocks ff_data.cf_blocks
#define ff_extents ff_data.cf_extents
+
+/*
+ * Note that the blocks fields are protected by the cnode lock, *not*
+ * the truncate lock.
+ */
+#define ff_blocks ff_data.cf_blocks
#define ff_unallocblocks ff_data.cf_vblocks
+static inline uint32_t ff_allocblocks(filefork_t *ff)
+{
+ assert(ff->ff_blocks >= ff->ff_unallocblocks);
+ return ff->ff_blocks - ff->ff_unallocblocks;
+}
#define ff_symlinkptr ff_union.ffu_symlinkptr
#define ff_sysfileinfo ff_union.ffu_sysfileinfo
#define fcbBTCBPtr ff_sysfileinfo
typedef u_int8_t atomicflag_t;
-
+
+
+/*
+ * Hardlink Origin (for hardlinked directories).
+ */
+struct linkorigin {
+ TAILQ_ENTRY(linkorigin) lo_link; /* chain */
+ void * lo_thread; /* thread that performed the lookup */
+ cnid_t lo_cnid; /* hardlink's cnid */
+ cnid_t lo_parentcnid; /* hardlink's parent cnid */
+};
+typedef struct linkorigin linkorigin_t;
+
+#define MAX_CACHED_ORIGINS 10
+#define MAX_CACHED_FILE_ORIGINS 8
+
/*
* The cnode is used to represent each active (or recently active)
* file or directory in the HFS filesystem.
*/
struct cnode {
lck_rw_t c_rwlock; /* cnode's lock */
- void * c_lockowner; /* cnode's lock owner (exclusive case only) */
+ thread_t c_lockowner; /* cnode's lock owner (exclusive case only) */
lck_rw_t c_truncatelock; /* protects file from truncation during read/write */
+ thread_t c_truncatelockowner; /* truncate lock owner (exclusive case only) */
LIST_ENTRY(cnode) c_hash; /* cnode's hash chain */
u_int32_t c_flag; /* cnode's runtime flags */
u_int32_t c_hflag; /* cnode's flags for maintaining hash - protected by global hash lock */
struct vnode *c_vp; /* vnode for data fork or dir */
struct vnode *c_rsrc_vp; /* vnode for resource fork */
- struct vnode *c_devvp; /* vnode for block I/O */
- dev_t c_dev; /* cnode's device */
- struct dquot *c_dquot[MAXQUOTAS]; /* cnode's quota info */
- struct klist c_knotes; /* knotes attached to this vnode */
- u_long c_childhint; /* catalog hint for children */
+ struct dquot *c_dquot[MAXQUOTAS]; /* cnode's quota info */
+ u_int32_t c_childhint; /* catalog hint for children (small dirs only) */
+ u_int32_t c_dirthreadhint; /* catalog hint for directory's thread rec */
struct cat_desc c_desc; /* cnode's descriptor */
struct cat_attr c_attr; /* cnode's attributes */
- TAILQ_HEAD(hfs_hinthead, directoryhint) c_hintlist; /* directory hint list */
+ TAILQ_HEAD(hfs_originhead, linkorigin) c_originlist; /* hardlink origin cache */
+ TAILQ_HEAD(hfs_hinthead, directoryhint) c_hintlist; /* readdir directory hint list */
int16_t c_dirhinttag; /* directory hint tag */
union {
int16_t cu_dirhintcnt; /* directory hint count */
int16_t cu_syslockcount; /* system file use only */
} c_union;
+ u_int32_t c_dirchangecnt; /* changes each insert/delete (in-core only) */
struct filefork *c_datafork; /* cnode's data fork */
struct filefork *c_rsrcfork; /* cnode's rsrc fork */
atomicflag_t c_touch_acctime;
atomicflag_t c_touch_chgtime;
atomicflag_t c_touch_modtime;
+
+ // The following flags are protected by the truncate lock
+ union {
+ struct {
+ bool c_need_dvnode_put_after_truncate_unlock : 1;
+ bool c_need_rvnode_put_after_truncate_unlock : 1;
+#if HFS_COMPRESSION
+ bool c_need_decmpfs_reset : 1;
+#endif
+ };
+ uint8_t c_tflags;
+ };
+
+ /*
+ * Where we're using a journal, we keep track of the last
+ * transaction that we did an update in. If a minor modification
+ * is made, we'll still push it if we're still on the same
+ * transaction.
+ */
+ uint32_t c_update_txn;
+
+#if HFS_COMPRESSION
+ decmpfs_cnode *c_decmp;
+#endif /* HFS_COMPRESSION */
+#if CONFIG_PROTECT
+ cprotect_t c_cpentry; /* content protection data */
+#endif
+
};
typedef struct cnode cnode_t;
#define c_fileid c_attr.ca_fileid
#define c_mode c_attr.ca_mode
-#define c_nlink c_attr.ca_nlink
+#define c_linkcount c_attr.ca_linkcount
#define c_uid c_attr.ca_uid
#define c_gid c_attr.ca_gid
-#define c_rdev c_attr.ca_rdev
+#define c_rdev c_attr.ca_union1.cau_rdev
#define c_atime c_attr.ca_atime
#define c_mtime c_attr.ca_mtime
#define c_ctime c_attr.ca_ctime
#define c_itime c_attr.ca_itime
#define c_btime c_attr.ca_btime
-#define c_flags c_attr.ca_flags
+#define c_bsdflags c_attr.ca_flags
#define c_finderinfo c_attr.ca_finderinfo
-#define c_blocks c_attr.ca_blocks
-#define c_attrblks c_attr.ca_attrblks
-#define c_entries c_attr.ca_entries
+#define c_blocks c_attr.ca_union2.cau_blocks
+#define c_entries c_attr.ca_union2.cau_entries
#define c_zftimeout c_childhint
#define c_dirhintcnt c_union.cu_dirhintcnt
#define H_WAITING 0x00008 /* CNode is being waited for */
-/* Runtime cnode flags (kept in c_flag) */
-#define C_NEED_RVNODE_PUT 0x00001 /* Need to do a vnode_put on c_rsrc_vp after the unlock */
-#define C_NEED_DVNODE_PUT 0x00002 /* Need to do a vnode_put on c_vp after the unlock */
-#define C_ZFWANTSYNC 0x00004 /* fsync requested and file has holes */
-#define C_FROMSYNC 0x00008 /* fsync was called from sync */
+/*
+ * Runtime cnode flags (kept in c_flag)
+ */
+#define C_NEED_RVNODE_PUT 0x0000001 /* Need to do a vnode_put on c_rsrc_vp after the unlock */
+#define C_NEED_DVNODE_PUT 0x0000002 /* Need to do a vnode_put on c_vp after the unlock */
+#define C_ZFWANTSYNC 0x0000004 /* fsync requested and file has holes */
+#define C_FROMSYNC 0x0000008 /* fsync was called from sync */
-#define C_MODIFIED 0x00010 /* CNode has been modified */
-#define C_NOEXISTS 0x00020 /* CNode has been deleted, catalog entry is gone */
-#define C_DELETED 0x00040 /* CNode has been marked to be deleted */
-#define C_HARDLINK 0x00080 /* CNode is a hard link */
+#define C_MODIFIED 0x0000010 /* CNode has been modified */
+#define C_NOEXISTS 0x0000020 /* CNode has been deleted, catalog entry is gone */
+#define C_DELETED 0x0000040 /* CNode has been marked to be deleted */
+#define C_HARDLINK 0x0000080 /* CNode is a hard link (file or dir) */
-#define C_FORCEUPDATE 0x00100 /* force the catalog entry update */
-#define C_HASXATTRS 0x00200 /* cnode has extended attributes */
+/*
+ * A minor modification is one where the volume would not be inconsistent if
+ * the change was not pushed to disk. For example, changes to times.
+ */
+#define C_MINOR_MOD 0x0000100 /* CNode has a minor modification */
+
+#define C_HASXATTRS 0x0000200 /* cnode has extended attributes */
+#define C_NEG_ENTRIES 0x0000400 /* directory has negative name entries */
+/*
+ * For C_SSD_STATIC: SSDs may want to deal with the file payload data in a
+ * different manner knowing that the content is not likely to be modified. This is
+ * purely advisory at the HFS level, and is not maintained after the cnode goes out of core.
+ */
+#define C_SSD_STATIC 0x0000800 /* Assume future writes contain static content */
+
+#define C_NEED_DATA_SETSIZE 0x0001000 /* Do a ubc_setsize(0) on c_rsrc_vp after the unlock */
+#define C_NEED_RSRC_SETSIZE 0x0002000 /* Do a ubc_setsize(0) on c_vp after the unlock */
+#define C_DIR_MODIFICATION 0x0004000 /* Directory is being modified, wait for lookups */
+#define C_ALWAYS_ZEROFILL 0x0008000 /* Always zero-fill the file on an fsync */
+
+#define C_RENAMED 0x0010000 /* cnode was deleted as part of rename; C_DELETED should also be set */
+#define C_NEEDS_DATEADDED 0x0020000 /* cnode needs date-added written to the finderinfo bit */
+#define C_BACKINGSTORE 0x0040000 /* cnode is a backing store for an existing or currently-mounting filesystem */
+/*
+ * This flag indicates the cnode might be dirty because it
+ * was mapped writable so if we get any page-outs, update
+ * the modification and change times.
+ */
+#define C_MIGHT_BE_DIRTY_FROM_MAPPING 0x0080000
+
+/*
+ * For C_SSD_GREEDY_MODE: SSDs may want to write the file payload data using the greedy mode knowing
+ * that the content needs to be written out to the disk quicker than normal at the expense of storage efficiency.
+ * This is purely advisory at the HFS level, and is not maintained after the cnode goes out of core.
+ */
+#define C_SSD_GREEDY_MODE 0x0100000 /* Assume future writes are recommended to be written in SLC mode */
+
+/* 0x0200000 is currently unused */
+
+#define C_IO_ISOCHRONOUS 0x0400000 /* device-specific isochronous throughput I/O */
#define ZFTIMELIMIT (5 * 60)
+/*
+ * The following is the "invisible" bit from the fdFlags field
+ * in the FndrFileInfo.
+ */
+enum { kFinderInvisibleMask = 1 << 14 };
+
+
/*
* Convert between cnode pointers and vnode pointers
*/
VTOC((vp))->c_rsrcfork : \
VTOC((vp))->c_datafork)
+#define VCTOF(vp, cp) ((vp) == (cp)->c_rsrc_vp ? \
+ (cp)->c_rsrcfork : \
+ (cp)->c_datafork)
+
#define FTOV(fp) ((fp) == FTOC(fp)->c_rsrcfork ? \
FTOC(fp)->c_rsrc_vp : \
FTOC(fp)->c_vp)
+/*
+ * This is a helper function used for determining whether or not a cnode has become open
+ * unlinked in between the time we acquired its vnode and the time we acquire the cnode lock
+ * to start manipulating it. Due to the SMP nature of VFS, it is probably necessary to
+ * use this macro every time we acquire a cnode lock, as the content of the Cnode may have
+ * been modified in betweeen the lookup and a VNOP. Whether or not to call this is dependent
+ * upon the VNOP in question. Sometimes it is OK to use an open-unlinked file, for example, in,
+ * reading. But other times, such as on the source of a VNOP_RENAME, it should be disallowed.
+ */
+int hfs_checkdeleted(struct cnode *cp);
/*
* Test for a resource fork
#define VNODE_IS_RSRC(vp) ((vp) == VTOC((vp))->c_rsrc_vp)
+#if HFS_COMPRESSION
+/*
+ * VTOCMP(vp) returns a pointer to vp's decmpfs_cnode; this could be NULL
+ * if the file is not compressed or if hfs_file_is_compressed() hasn't
+ * yet been called on this file.
+ */
+#define VTOCMP(vp) (VTOC((vp))->c_decmp)
+int hfs_file_is_compressed(struct cnode *cp, int skiplock);
+int hfs_uncompressed_size_of_compressed_file(struct hfsmount *hfsmp, struct vnode *vp, cnid_t fid, off_t *size, int skiplock);
+int hfs_hides_rsrc(vfs_context_t ctx, struct cnode *cp, int skiplock);
+int hfs_hides_xattr(vfs_context_t ctx, struct cnode *cp, const char *name, int skiplock);
+#endif
#define ATIME_ONDISK_ACCURACY 300
+static inline bool hfs_should_save_atime(cnode_t *cp)
+{
+ /*
+ * We only write atime updates to disk if the delta is greater
+ * than ATIME_ONDISK_ACCURACY.
+ */
+ return (cp->c_atime < cp->c_attr.ca_atimeondisk
+ || cp->c_atime - cp->c_attr.ca_atimeondisk > ATIME_ONDISK_ACCURACY);
+}
+
+typedef enum {
+ HFS_NOT_DIRTY = 0,
+ HFS_DIRTY = 1,
+ HFS_DIRTY_ATIME = 2
+} hfs_dirty_t;
+
+static inline hfs_dirty_t hfs_is_dirty(cnode_t *cp)
+{
+ if (ISSET(cp->c_flag, C_NOEXISTS))
+ return HFS_NOT_DIRTY;
+
+ if (ISSET(cp->c_flag, C_MODIFIED | C_MINOR_MOD | C_NEEDS_DATEADDED)
+ || cp->c_touch_chgtime || cp->c_touch_modtime) {
+ return HFS_DIRTY;
+ }
+
+ if (cp->c_touch_acctime || hfs_should_save_atime(cp))
+ return HFS_DIRTY_ATIME;
+
+ return HFS_NOT_DIRTY;
+}
/* This overlays the FileID portion of NFS file handles. */
struct hfsfid {
};
+/* Get new default vnode */
+extern int hfs_getnewvnode(struct hfsmount *hfsmp, struct vnode *dvp, struct componentname *cnp,
+ struct cat_desc *descp, int flags, struct cat_attr *attrp,
+ struct cat_fork *forkp, struct vnode **vpp, int *out_flags);
+
+/* Input flags for hfs_getnewvnode */
+
+#define GNV_WANTRSRC 0x01 /* Request the resource fork vnode. */
+#define GNV_SKIPLOCK 0x02 /* Skip taking the cnode lock (when getting resource fork). */
+#define GNV_CREATE 0x04 /* The vnode is for a newly created item. */
+#define GNV_NOCACHE 0x08 /* Delay entering this item in the name cache */
+#define GNV_USE_VP 0x10 /* Use the vnode provided in *vpp instead of creating a new one */
+
+/* Output flags for hfs_getnewvnode */
+#define GNV_CHASH_RENAMED 0x01 /* The cnode was renamed in-flight */
+#define GNV_CAT_DELETED 0x02 /* The cnode was deleted from the catalog */
+#define GNV_NEW_CNODE 0x04 /* We are vending out a newly initialized cnode */
+#define GNV_CAT_ATTRCHANGED 0x08 /* Something in struct cat_attr changed in between cat_lookups */
+
+
+/* Touch cnode times based on c_touch_xxx flags */
extern void hfs_touchtimes(struct hfsmount *, struct cnode *);
+extern void hfs_write_dateadded (struct cat_attr *cattrp, u_int32_t dateadded);
+extern u_int32_t hfs_get_dateadded (struct cnode *cp);
+extern u_int32_t hfs_get_dateadded_from_blob(const uint8_t * /* finderinfo */, mode_t /* mode */);
+
+/* Gen counter methods */
+extern void hfs_write_gencount(struct cat_attr *cattrp, uint32_t gencount);
+extern uint32_t hfs_get_gencount(struct cnode *cp);
+extern uint32_t hfs_incr_gencount (struct cnode *cp);
+extern uint32_t hfs_get_gencount_from_blob(const uint8_t * /* finderinfo */, mode_t /* mode */);
+
+/* Document id methods */
+extern uint32_t hfs_get_document_id(struct cnode * /* cp */);
+extern uint32_t hfs_get_document_id_from_blob(const uint8_t * /* finderinfo */, mode_t /* mode */);
+
+/* Zero-fill file and push regions out to disk */
+enum {
+ // Use this flag if you're going to sync later
+ HFS_FILE_DONE_NO_SYNC = 1,
+};
+typedef uint32_t hfs_file_done_opts_t;
+extern int hfs_filedone(struct vnode *vp, vfs_context_t context,
+ hfs_file_done_opts_t opts);
/*
* HFS cnode hash functions.
*/
extern void hfs_chashinit(void);
-extern void hfs_chashinsert(struct cnode *cp);
-extern int hfs_chashremove(struct cnode *cp);
-extern void hfs_chash_abort(struct cnode *cp);
-extern void hfs_chash_rehash(struct cnode *cp1, struct cnode *cp2);
-extern void hfs_chashwakeup(struct cnode *cp, int flags);
-extern void hfs_chash_mark_in_transit(struct cnode *cp);
-
-extern struct vnode * hfs_chash_getvnode(dev_t dev, ino_t inum, int wantrsrc, int skiplock);
-extern struct cnode * hfs_chash_getcnode(dev_t dev, ino_t inum, struct vnode **vpp, int wantrsrc, int skiplock);
-extern int hfs_chash_snoop(dev_t, ino_t, int (*)(const struct cat_desc *,
- const struct cat_attr *, void *), void *);
-
-/*
- * HFS directory hint functions.
- */
-extern directoryhint_t * hfs_getdirhint(struct cnode *, int);
-extern void hfs_reldirhint(struct cnode *, directoryhint_t *);
-extern void hfs_reldirhints(struct cnode *, int);
+extern void hfs_chashinit_finish(struct hfsmount *hfsmp);
+extern void hfs_delete_chash(struct hfsmount *hfsmp);
+extern int hfs_chashremove(struct hfsmount *hfsmp, struct cnode *cp);
+extern void hfs_chash_abort(struct hfsmount *hfsmp, struct cnode *cp);
+extern void hfs_chash_rehash(struct hfsmount *hfsmp, struct cnode *cp1, struct cnode *cp2);
+extern void hfs_chashwakeup(struct hfsmount *hfsmp, struct cnode *cp, int flags);
+extern void hfs_chash_mark_in_transit(struct hfsmount *hfsmp, struct cnode *cp);
+
+extern struct vnode * hfs_chash_getvnode(struct hfsmount *hfsmp, ino_t inum, int wantrsrc,
+ int skiplock, int allow_deleted);
+extern struct cnode * hfs_chash_getcnode(struct hfsmount *hfsmp, ino_t inum, struct vnode **vpp,
+ int wantrsrc, int skiplock, int *out_flags, int *hflags);
+extern int hfs_chash_snoop(struct hfsmount *, ino_t, int, int (*)(const cnode_t *, void *), void *);
+extern int hfs_valid_cnode(struct hfsmount *hfsmp, struct vnode *dvp, struct componentname *cnp,
+ cnid_t cnid, struct cat_attr *cattr, int *error);
+
+extern int hfs_chash_set_childlinkbit(struct hfsmount *hfsmp, cnid_t cnid);
/*
* HFS cnode lock functions.
*
* HFS Locking Order:
*
- * 1. cnode truncate lock (if needed)
- * 2. cnode lock (in parent-child order if related, otherwise by address order)
- * 3. journal (if needed)
- * 4. system files (as needed)
+ * 1. cnode truncate lock (if needed) -- see below for more on this
+ *
+ * + hfs_vnop_pagein/out handles recursive use of this lock (by
+ * using flag option HFS_LOCK_SKIP_IF_EXCLUSIVE) although there
+ * are issues with this (see #16620278).
+ *
+ * + If locking multiple cnodes then the truncate lock must be taken on
+ * all (in address order), before taking the cnode locks.
+ *
+ * 2. Hot Files stage mutex (grabbed before manipulating individual vnodes/cnodes)
+ *
+ * 3. cnode locks in address order (if needed)
+ *
+ * 4. journal (if needed)
+ *
+ * 5. Hot Files B-Tree lock (not treated as a system file)
+ *
+ * 6. system files (as needed)
+ *
* A. Catalog B-tree file
* B. Attributes B-tree file
- * C. Allocation Bitmap file (always exclusive, supports recursion)
- * D. Overflow Extents B-tree file (always exclusive, supports recursion)
- * 5. hfs mount point (always last)
+ * C. Startup file (if there is one)
+ * D. Allocation Bitmap file (always exclusive, supports recursion)
+ * E. Overflow Extents B-tree file (always exclusive, supports recursion)
+ *
+ * 7. hfs mount point (always last)
+ *
*
+ * I. HFS cnode hash lock (must not acquire any new locks while holding this lock, always taken last)
*/
-enum hfslocktype {HFS_SHARED_LOCK = 1, HFS_EXCLUSIVE_LOCK = 2, HFS_FORCE_LOCK = 3};
-#define HFS_SHARED_OWNER (void *)0xffffffff
-extern int hfs_lock(struct cnode *, enum hfslocktype);
-extern int hfs_lockpair(struct cnode *, struct cnode *, enum hfslocktype);
-extern int hfs_lockfour(struct cnode *, struct cnode *, struct cnode *, struct cnode *,
- enum hfslocktype);
+/*
+ * -- The Truncate Lock --
+ *
+ * The truncate lock is used for a few purposes (more than its name
+ * might suggest). The first thing to note is that the cnode lock
+ * cannot be held whilst issuing any I/O other than metadata changes,
+ * so the truncate lock, in either shared or exclusive form, must
+ * usually be held in these cases. This includes calls to ubc_setsize
+ * where the new size is less than the current size known to the VM
+ * subsystem (for two reasons: a) because reaping pages can block
+ * (e.g. on pages that are busy or being cleaned); b) reaping pages
+ * might require page-in for tasks that have that region mapped
+ * privately). The same applies to other calls into the VM subsystem.
+ *
+ * Here are some (but not necessarily all) cases that the truncate
+ * lock protects for:
+ *
+ * + When reading and writing a file, we hold the truncate lock
+ * shared to ensure that the underlying blocks cannot be deleted
+ * and on systems that use content protection, this also ensures
+ * the keys remain valid (which might be being used by the
+ * underlying layers).
+ *
+ * + We need to protect against the following sequence of events:
+ *
+ * A file is initially size X. A thread issues an append to that
+ * file. Another thread truncates the file and then extends it
+ * to a a new size Y. Now the append can be applied at offset X
+ * and then the data is lost when the file is truncated; or it
+ * could be applied after the truncate, i.e. at offset 0; or it
+ * can be applied at offset Y. What we *cannot* do is apply the
+ * append at offset X and for the data to be visible at the end.
+ * (Note that we are free to choose when we apply the append
+ * operation.)
+ *
+ * To solve this, we keep things simple and take the truncate lock
+ * exclusively in order to sequence the append with other size
+ * changes. Therefore any size change must take the truncate lock
+ * exclusively.
+ *
+ * (N.B. we could do better and allow readers to run concurrently
+ * during the append and other size changes.)
+ *
+ * So here are the rules:
+ *
+ * + If you plan to change ff_size, you must take the truncate lock
+ * exclusively, *but* be careful what I/O you do whilst you have
+ * the truncate lock exclusively and try and avoid it if you can:
+ * if the VM subsystem tries to do something with some pages on a
+ * different thread and you try and do some I/O with those same
+ * pages, we will deadlock. (See #16620278.)
+ *
+ * + If you do anything that requires blocks to not be deleted or
+ * encryption keys to remain valid, you must take the truncate lock
+ * shared.
+ *
+ * + And it follows therefore, that if you want to delete blocks or
+ * delete keys, you must take the truncate lock exclusively. Note
+ * that for asynchronous writes, the truncate lock will be dropped
+ * after issuing I/O but before the I/O has completed which means
+ * that before manipulating keys, you *must* issue
+ * vnode_wait_for_writes in addition to holding the truncate lock.
+ *
+ * N.B. ff_size is actually protected by the cnode lock and so you
+ * must hold the cnode lock exclusively to change it and shared to
+ * read it.
+ *
+ */
-extern void hfs_unlock(struct cnode *);
-extern void hfs_unlockpair(struct cnode *, struct cnode *);
-extern void hfs_unlockfour(struct cnode *, struct cnode *, struct cnode *, struct cnode *);
+enum hfs_locktype {
+ HFS_SHARED_LOCK = 1,
+ HFS_EXCLUSIVE_LOCK = 2
+};
+
+/* Option flags for cnode and truncate lock functions */
+enum hfs_lockflags {
+ HFS_LOCK_DEFAULT = 0x0, /* Default flag, no options provided */
+ HFS_LOCK_ALLOW_NOEXISTS = 0x1, /* Allow locking of all cnodes, including cnode marked deleted with no catalog entry */
+ HFS_LOCK_SKIP_IF_EXCLUSIVE = 0x2, /* Skip locking if the current thread already holds the lock exclusive */
+
+ // Used when you do not want to check return from hfs_lock
+ HFS_LOCK_ALWAYS = HFS_LOCK_ALLOW_NOEXISTS,
+};
+#define HFS_SHARED_OWNER (void *)0xffffffff
-extern void hfs_lock_truncate(struct cnode *, int);
-extern void hfs_unlock_truncate(struct cnode *);
+void hfs_lock_always(cnode_t *cnode, enum hfs_locktype);
+int hfs_lock(struct cnode *, enum hfs_locktype, enum hfs_lockflags);
+bool hfs_lock_upgrade(cnode_t *cp);
+int hfs_lockpair(struct cnode *, struct cnode *, enum hfs_locktype);
+int hfs_lockfour(struct cnode *, struct cnode *, struct cnode *, struct cnode *,
+ enum hfs_locktype, struct cnode **);
+void hfs_unlock(struct cnode *);
+void hfs_unlockpair(struct cnode *, struct cnode *);
+void hfs_unlockfour(struct cnode *, struct cnode *, struct cnode *, struct cnode *);
+
+void hfs_lock_truncate(struct cnode *, enum hfs_locktype, enum hfs_lockflags);
+bool hfs_truncate_lock_upgrade(struct cnode *cp);
+void hfs_truncate_lock_downgrade(struct cnode *cp);
+void hfs_unlock_truncate(struct cnode *, enum hfs_lockflags);
+int hfs_try_trunclock(struct cnode *, enum hfs_locktype, enum hfs_lockflags);
+
+extern int hfs_systemfile_lock(struct hfsmount *, int, enum hfs_locktype);
+extern void hfs_systemfile_unlock(struct hfsmount *, int);
+
+void hfs_clear_might_be_dirty_flag(cnode_t *cp);
+
+// cnode must be locked
+static inline __attribute__((pure))
+bool hfs_has_rsrc(const cnode_t *cp)
+{
+ if (cp->c_rsrcfork)
+ return cp->c_rsrcfork->ff_blocks > 0;
+ else
+ return cp->c_datafork && cp->c_blocks > cp->c_datafork->ff_blocks;
+}
#endif /* __APPLE_API_PRIVATE */
#endif /* KERNEL */
projects / apple / xnu.git / blobdiff