X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/8ad349bb6ed4a0be06e34c92be0d98b92e078db4..3e170ce000f1506b7b5d2c5c7faec85ceabb573d:/bsd/hfs/hfs_cnode.h?ds=sidebyside diff --git a/bsd/hfs/hfs_cnode.h b/bsd/hfs/hfs_cnode.h index ed95c2ca8..d45b9d236 100644 --- a/bsd/hfs/hfs_cnode.h +++ b/bsd/hfs/hfs_cnode.h @@ -1,31 +1,29 @@ /* - * Copyright (c) 2002-2005 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2002-2014 Apple Inc. All rights reserved. * - * @APPLE_LICENSE_OSREFERENCE_HEADER_START@ + * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * - * 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. - * - * 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, QUIET ENJOYMENT OR NON-INFRINGEMENT. - * Please see the License for the specific language governing rights and + * 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. + * + * 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, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * Please see the License for the specific language governing rights and * limitations under the License. - * - * @APPLE_LICENSE_OSREFERENCE_HEADER_END@ + * + * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #ifndef _HFS_CNODE_H_ #define _HFS_CNODE_H_ @@ -34,6 +32,7 @@ #ifdef KERNEL #ifdef __APPLE_API_PRIVATE +#include #include #include #include @@ -44,7 +43,13 @@ #include #include - +#if HFS_COMPRESSION +#include +#endif +#if CONFIG_PROTECT +#include +#endif +#include /* * The filefork is used to represent an HFS file fork (data or resource). @@ -61,13 +66,48 @@ struct filefork { }; 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 @@ -79,7 +119,22 @@ typedef struct filefork filefork_t; #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. @@ -88,31 +143,60 @@ typedef u_int8_t atomicflag_t; */ 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; @@ -124,20 +208,19 @@ 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 @@ -151,23 +234,70 @@ typedef struct cnode cnode_t; #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 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) */ + +/* + * 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_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_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 */ -#define C_FORCEUPDATE 0x00100 /* force the catalog entry update */ -#define C_HASXATTRS 0x00200 /* cnode has extended attributes */ +/* + * 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 */ @@ -188,10 +318,24 @@ typedef struct cnode cnode_t; 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 @@ -200,9 +344,52 @@ typedef struct cnode cnode_t; #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 { @@ -211,61 +398,224 @@ 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. + * + */ + +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 */ -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 *); + // 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 */