linux-zen-server/fs/xfs/libxfs/xfs_attr.h

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2023-08-30 17:53:23 +02:00
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#ifndef __XFS_ATTR_H__
#define __XFS_ATTR_H__
struct xfs_inode;
struct xfs_da_args;
struct xfs_attr_list_context;
/*
* Large attribute lists are structured around Btrees where all the data
* elements are in the leaf nodes. Attribute names are hashed into an int,
* then that int is used as the index into the Btree. Since the hashval
* of an attribute name may not be unique, we may have duplicate keys.
* The internal links in the Btree are logical block offsets into the file.
*
* Small attribute lists use a different format and are packed as tightly
* as possible so as to fit into the literal area of the inode.
*/
/*
* The maximum size (into the kernel or returned from the kernel) of an
* attribute value or the buffer used for an attr_list() call. Larger
* sizes will result in an ERANGE return code.
*/
#define ATTR_MAX_VALUELEN (64*1024) /* max length of a value */
/*
* Kernel-internal version of the attrlist cursor.
*/
struct xfs_attrlist_cursor_kern {
__u32 hashval; /* hash value of next entry to add */
__u32 blkno; /* block containing entry (suggestion) */
__u32 offset; /* offset in list of equal-hashvals */
__u16 pad1; /* padding to match user-level */
__u8 pad2; /* padding to match user-level */
__u8 initted; /* T/F: cursor has been initialized */
};
/*========================================================================
* Structure used to pass context around among the routines.
*========================================================================*/
/* void; state communicated via *context */
typedef void (*put_listent_func_t)(struct xfs_attr_list_context *, int,
unsigned char *, int, int);
struct xfs_attr_list_context {
struct xfs_trans *tp;
struct xfs_inode *dp; /* inode */
struct xfs_attrlist_cursor_kern cursor; /* position in list */
void *buffer; /* output buffer */
/*
* Abort attribute list iteration if non-zero. Can be used to pass
* error values to the xfs_attr_list caller.
*/
int seen_enough;
bool allow_incomplete;
ssize_t count; /* num used entries */
int dupcnt; /* count dup hashvals seen */
int bufsize; /* total buffer size */
int firstu; /* first used byte in buffer */
unsigned int attr_filter; /* XFS_ATTR_{ROOT,SECURE} */
int resynch; /* T/F: resynch with cursor */
put_listent_func_t put_listent; /* list output fmt function */
int index; /* index into output buffer */
};
/*
* ========================================================================
* Structure used to pass context around among the delayed routines.
* ========================================================================
*/
/*
* Below is a state machine diagram for attr remove operations. The XFS_DAS_*
* states indicate places where the function would return -EAGAIN, and then
* immediately resume from after being called by the calling function. States
* marked as a "subroutine state" indicate that they belong to a subroutine, and
* so the calling function needs to pass them back to that subroutine to allow
* it to finish where it left off. But they otherwise do not have a role in the
* calling function other than just passing through.
*
* xfs_attr_remove_iter()
*
* v
* have attr to remove? n> done
*
* y
*
* v
* are we short form? y> xfs_attr_shortform_remove > done
*
* n
*
* V
* are we leaf form? y> xfs_attr_leaf_removename > done
*
* n
*
* V
* need to setup state?
*
* n y
*
* v
* find attr and get state
* attr has remote blks? n
* v
* find and invalidate
* y the remote blocks.
* mark attr incomplete
*
*
*
* v
* Have remote blks to remove? y
* ^ remove the blks
*
* v
* XFS_DAS_RMTBLK <n done?
* re-enter with
* one less blk to y
* remove
* V
* refill the state
* n
* v
* XFS_DAS_RM_NAME
*
*
*
* v
* remove leaf and
* update hash with
* xfs_attr_node_remove_cleanup
*
* v
* need to
* shrink tree? n
*
* y
*
* v
* join leaf
*
* v
* XFS_DAS_RM_SHRINK
*
* v
* do the shrink
*
* v
* free state <
*
* v
* done
*
*
* Below is a state machine diagram for attr set operations.
*
* It seems the challenge with understanding this system comes from trying to
* absorb the state machine all at once, when really one should only be looking
* at it with in the context of a single function. Once a state sensitive
* function is called, the idea is that it "takes ownership" of the
* state machine. It isn't concerned with the states that may have belonged to
* it's calling parent. Only the states relevant to itself or any other
* subroutines there in. Once a calling function hands off the state machine to
* a subroutine, it needs to respect the simple rule that it doesn't "own" the
* state machine anymore, and it's the responsibility of that calling function
* to propagate the -EAGAIN back up the call stack. Upon reentry, it is
* committed to re-calling that subroutine until it returns something other than
* -EAGAIN. Once that subroutine signals completion (by returning anything other
* than -EAGAIN), the calling function can resume using the state machine.
*
* xfs_attr_set_iter()
*
* v
* y has an attr fork?
* |
* n
* |
* V
* add a fork
*
*
*
* V
* is shortform?
*
* y
*
* V
* xfs_attr_set_fmt
* |
* V
* xfs_attr_try_sf_addname
*
* V
* had enough y> done
* space?
* n
* n
*
* V
* transform to leaf
*
* V
* hold the leaf buffer
*
* V
* return -EAGAIN
* Re-enter in
* leaf form
*
* > release leaf buffer
* if needed
*
* V
* n fork has
* only 1 blk?
*
* y
*
* v
* xfs_attr_leaf_try_add()
*
* v
* had enough y
* space?
*
* n
*
* v
* return -EAGAIN
* re-enter in
* node form
*
*
*
* V
* xfs_attr_node_addname_find_attr
* determines if this
* is create or rename
* find space to store attr
*
* v
* xfs_attr_node_addname
*
* v
* fits in a node leaf? n
* ^ v
* single leaf node?
*
* y y n
*
* v v v
* update grow the leaf split if
* hashvals return -EAGAIN needed
* retry leaf add
* on reentry
*
*
* v
* need to alloc
* y or flip flag?
*
* n
*
* v
* done
*
*
* XFS_DAS_FOUND_LBLK <
*
* V
* xfs_attr_leaf_addname()
*
* v
* first time through?
*
* y
*
* n v
* if we have rmt blks
* find space for them
*
*
*
* v
* still have
* n blks to alloc? <
*
* y
*
* v
* alloc one blk
* return -EAGAIN
* re-enter with one
* less blk to alloc
*
*
* > set the rmt
* value
*
* v
* was this
* a rename? n
*
* y
*
* v
* flip incomplete
* flag
*
* v
* XFS_DAS_FLIP_LFLAG
*
* v
* need to remove
* old bks? n
*
* y
*
* V
* remove
* > old blks
*
* XFS_DAS_RM_LBLK
* ^
* v
* y more to
* remove?
*
* n
*
* v
* XFS_DAS_RD_LEAF
*
* v
* remove leaf
*
* v
* shrink to sf
* if needed
*
* v
* done <
*
* > XFS_DAS_FOUND_NBLK
*
* v
* n need to
* alloc blks?
*
* y
*
* v
* find space
*
* v
* >XFS_DAS_ALLOC_NODE
*
* v
* alloc blk
*
* v
* y need to alloc
* more blocks?
*
* n
*
* v
* set the rmt value
*
* v
* was this
* > a rename? n
*
* y
*
* v
* flip incomplete
* flag
*
* v
* XFS_DAS_FLIP_NFLAG
*
* v
* need to
* remove blks? n
*
* y
*
* v
* remove
* > old blks
*
* XFS_DAS_RM_NBLK
* ^
* v
* y more to
* remove
*
* n
*
* v
* XFS_DAS_CLR_FLAG
*
* v
* clear flags
*
*
*
* v
* done
*/
/*
* Enum values for xfs_attr_intent.xattri_da_state
*
* These values are used by delayed attribute operations to keep track of where
* they were before they returned -EAGAIN. A return code of -EAGAIN signals the
* calling function to roll the transaction, and then call the subroutine to
* finish the operation. The enum is then used by the subroutine to jump back
* to where it was and resume executing where it left off.
*/
enum xfs_delattr_state {
XFS_DAS_UNINIT = 0, /* No state has been set yet */
/*
* Initial sequence states. The replace setup code relies on the
* ADD and REMOVE states for a specific format to be sequential so
* that we can transform the initial operation to be performed
* according to the xfs_has_larp() state easily.
*/
XFS_DAS_SF_ADD, /* Initial sf add state */
XFS_DAS_SF_REMOVE, /* Initial sf replace/remove state */
XFS_DAS_LEAF_ADD, /* Initial leaf add state */
XFS_DAS_LEAF_REMOVE, /* Initial leaf replace/remove state */
XFS_DAS_NODE_ADD, /* Initial node add state */
XFS_DAS_NODE_REMOVE, /* Initial node replace/remove state */
/* Leaf state set/replace/remove sequence */
XFS_DAS_LEAF_SET_RMT, /* set a remote xattr from a leaf */
XFS_DAS_LEAF_ALLOC_RMT, /* We are allocating remote blocks */
XFS_DAS_LEAF_REPLACE, /* Perform replace ops on a leaf */
XFS_DAS_LEAF_REMOVE_OLD, /* Start removing old attr from leaf */
XFS_DAS_LEAF_REMOVE_RMT, /* A rename is removing remote blocks */
XFS_DAS_LEAF_REMOVE_ATTR, /* Remove the old attr from a leaf */
/* Node state sequence, must match leaf state above */
XFS_DAS_NODE_SET_RMT, /* set a remote xattr from a node */
XFS_DAS_NODE_ALLOC_RMT, /* We are allocating remote blocks */
XFS_DAS_NODE_REPLACE, /* Perform replace ops on a node */
XFS_DAS_NODE_REMOVE_OLD, /* Start removing old attr from node */
XFS_DAS_NODE_REMOVE_RMT, /* A rename is removing remote blocks */
XFS_DAS_NODE_REMOVE_ATTR, /* Remove the old attr from a node */
XFS_DAS_DONE, /* finished operation */
};
#define XFS_DAS_STRINGS \
{ XFS_DAS_UNINIT, "XFS_DAS_UNINIT" }, \
{ XFS_DAS_SF_ADD, "XFS_DAS_SF_ADD" }, \
{ XFS_DAS_SF_REMOVE, "XFS_DAS_SF_REMOVE" }, \
{ XFS_DAS_LEAF_ADD, "XFS_DAS_LEAF_ADD" }, \
{ XFS_DAS_LEAF_REMOVE, "XFS_DAS_LEAF_REMOVE" }, \
{ XFS_DAS_NODE_ADD, "XFS_DAS_NODE_ADD" }, \
{ XFS_DAS_NODE_REMOVE, "XFS_DAS_NODE_REMOVE" }, \
{ XFS_DAS_LEAF_SET_RMT, "XFS_DAS_LEAF_SET_RMT" }, \
{ XFS_DAS_LEAF_ALLOC_RMT, "XFS_DAS_LEAF_ALLOC_RMT" }, \
{ XFS_DAS_LEAF_REPLACE, "XFS_DAS_LEAF_REPLACE" }, \
{ XFS_DAS_LEAF_REMOVE_OLD, "XFS_DAS_LEAF_REMOVE_OLD" }, \
{ XFS_DAS_LEAF_REMOVE_RMT, "XFS_DAS_LEAF_REMOVE_RMT" }, \
{ XFS_DAS_LEAF_REMOVE_ATTR, "XFS_DAS_LEAF_REMOVE_ATTR" }, \
{ XFS_DAS_NODE_SET_RMT, "XFS_DAS_NODE_SET_RMT" }, \
{ XFS_DAS_NODE_ALLOC_RMT, "XFS_DAS_NODE_ALLOC_RMT" }, \
{ XFS_DAS_NODE_REPLACE, "XFS_DAS_NODE_REPLACE" }, \
{ XFS_DAS_NODE_REMOVE_OLD, "XFS_DAS_NODE_REMOVE_OLD" }, \
{ XFS_DAS_NODE_REMOVE_RMT, "XFS_DAS_NODE_REMOVE_RMT" }, \
{ XFS_DAS_NODE_REMOVE_ATTR, "XFS_DAS_NODE_REMOVE_ATTR" }, \
{ XFS_DAS_DONE, "XFS_DAS_DONE" }
struct xfs_attri_log_nameval;
/*
* Context used for keeping track of delayed attribute operations
*/
struct xfs_attr_intent {
/*
* used to log this item to an intent containing a list of attrs to
* commit later
*/
struct list_head xattri_list;
/* Used in xfs_attr_node_removename to roll through removing blocks */
struct xfs_da_state *xattri_da_state;
struct xfs_da_args *xattri_da_args;
/*
* Shared buffer containing the attr name and value so that the logging
* code can share large memory buffers between log items.
*/
struct xfs_attri_log_nameval *xattri_nameval;
/* Used to keep track of current state of delayed operation */
enum xfs_delattr_state xattri_dela_state;
/*
* Attr operation being performed - XFS_ATTRI_OP_FLAGS_*
*/
unsigned int xattri_op_flags;
/* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
xfs_dablk_t xattri_lblkno;
int xattri_blkcnt;
struct xfs_bmbt_irec xattri_map;
};
/*========================================================================
* Function prototypes for the kernel.
*========================================================================*/
/*
* Overall external interface routines.
*/
int xfs_attr_inactive(struct xfs_inode *dp);
int xfs_attr_list_ilocked(struct xfs_attr_list_context *);
int xfs_attr_list(struct xfs_attr_list_context *);
int xfs_inode_hasattr(struct xfs_inode *ip);
bool xfs_attr_is_leaf(struct xfs_inode *ip);
int xfs_attr_get_ilocked(struct xfs_da_args *args);
int xfs_attr_get(struct xfs_da_args *args);
int xfs_attr_set(struct xfs_da_args *args);
int xfs_attr_set_iter(struct xfs_attr_intent *attr);
int xfs_attr_remove_iter(struct xfs_attr_intent *attr);
bool xfs_attr_namecheck(const void *name, size_t length);
int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
void xfs_init_attr_trans(struct xfs_da_args *args, struct xfs_trans_res *tres,
unsigned int *total);
/*
* Check to see if the attr should be upgraded from non-existent or shortform to
* single-leaf-block attribute list.
*/
static inline bool
xfs_attr_is_shortform(
struct xfs_inode *ip)
{
return ip->i_af.if_format == XFS_DINODE_FMT_LOCAL ||
(ip->i_af.if_format == XFS_DINODE_FMT_EXTENTS &&
ip->i_af.if_nextents == 0);
}
static inline enum xfs_delattr_state
xfs_attr_init_add_state(struct xfs_da_args *args)
{
/*
* When called from the completion of a attr remove to determine the
* next state, the attribute fork may be null. This can occur only occur
* on a pure remove, but we grab the next state before we check if a
* replace operation is being performed. If we are called from any other
* context, i_af is guaranteed to exist. Hence if the attr fork is
* null, we were called from a pure remove operation and so we are done.
*/
if (!xfs_inode_has_attr_fork(args->dp))
return XFS_DAS_DONE;
args->op_flags |= XFS_DA_OP_ADDNAME;
if (xfs_attr_is_shortform(args->dp))
return XFS_DAS_SF_ADD;
if (xfs_attr_is_leaf(args->dp))
return XFS_DAS_LEAF_ADD;
return XFS_DAS_NODE_ADD;
}
static inline enum xfs_delattr_state
xfs_attr_init_remove_state(struct xfs_da_args *args)
{
args->op_flags |= XFS_DA_OP_REMOVE;
if (xfs_attr_is_shortform(args->dp))
return XFS_DAS_SF_REMOVE;
if (xfs_attr_is_leaf(args->dp))
return XFS_DAS_LEAF_REMOVE;
return XFS_DAS_NODE_REMOVE;
}
/*
* If we are logging the attributes, then we have to start with removal of the
* old attribute so that there is always consistent state that we can recover
* from if the system goes down part way through. We always log the new attr
* value, so even when we remove the attr first we still have the information in
* the log to finish the replace operation atomically.
*/
static inline enum xfs_delattr_state
xfs_attr_init_replace_state(struct xfs_da_args *args)
{
args->op_flags |= XFS_DA_OP_ADDNAME | XFS_DA_OP_REPLACE;
if (args->op_flags & XFS_DA_OP_LOGGED)
return xfs_attr_init_remove_state(args);
return xfs_attr_init_add_state(args);
}
extern struct kmem_cache *xfs_attr_intent_cache;
int __init xfs_attr_intent_init_cache(void);
void xfs_attr_intent_destroy_cache(void);
#endif /* __XFS_ATTR_H__ */