linux/fs/xfs/libxfs/xfs_attr.h
Darrick J. Wong e53bcffad0 xfs: don't hold xattr leaf buffers across transaction rolls
Now that we've established (again!) that empty xattr leaf buffers are
ok, we no longer need to bhold them to transactions when we're creating
new leaf blocks.  Get rid of the entire mechanism, which should simplify
the xattr code quite a bit.

The original justification for using bhold here was to prevent the AIL
from trying to write the empty leaf block into the fs during the brief
time that we release the buffer lock.  The reason for /that/ was to
prevent recovery from tripping over the empty ondisk block.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2022-06-29 08:47:56 -07:00

622 lines
23 KiB
C

/* 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_afp->if_format == XFS_DINODE_FMT_LOCAL ||
(ip->i_afp->if_format == XFS_DINODE_FMT_EXTENTS &&
ip->i_afp->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_afp 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 (!args->dp->i_afp)
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__ */