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8f502a4009
This patch modifies the attr set routines to be delay ready. This means they no longer roll or commit transactions, but instead return -EAGAIN to have the calling routine roll and refresh the transaction. In this series, xfs_attr_set_args has become xfs_attr_set_iter, which uses a state machine like switch to keep track of where it was when EAGAIN was returned. See xfs_attr.h for a more detailed diagram of the states. Two new helper functions have been added: xfs_attr_rmtval_find_space and xfs_attr_rmtval_set_blk. They provide a subset of logic similar to xfs_attr_rmtval_set, but they store the current block in the delay attr context to allow the caller to roll the transaction between allocations. This helps to simplify and consolidate code used by xfs_attr_leaf_addname and xfs_attr_node_addname. xfs_attr_set_args has now become a simple loop to refresh the transaction until the operation is completed. Lastly, xfs_attr_rmtval_remove is no longer used, and is removed. Signed-off-by: Allison Henderson <allison.henderson@oracle.com> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Brian Foster <bfoster@redhat.com>
500 lines
19 KiB
C
500 lines
19 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*/
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#ifndef __XFS_ATTR_H__
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#define __XFS_ATTR_H__
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struct xfs_inode;
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struct xfs_da_args;
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struct xfs_attr_list_context;
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/*
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* Large attribute lists are structured around Btrees where all the data
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* elements are in the leaf nodes. Attribute names are hashed into an int,
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* then that int is used as the index into the Btree. Since the hashval
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* of an attribute name may not be unique, we may have duplicate keys.
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* The internal links in the Btree are logical block offsets into the file.
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*
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* Small attribute lists use a different format and are packed as tightly
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* as possible so as to fit into the literal area of the inode.
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*/
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/*
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* The maximum size (into the kernel or returned from the kernel) of an
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* attribute value or the buffer used for an attr_list() call. Larger
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* sizes will result in an ERANGE return code.
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*/
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#define ATTR_MAX_VALUELEN (64*1024) /* max length of a value */
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/*
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* Kernel-internal version of the attrlist cursor.
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*/
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struct xfs_attrlist_cursor_kern {
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__u32 hashval; /* hash value of next entry to add */
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__u32 blkno; /* block containing entry (suggestion) */
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__u32 offset; /* offset in list of equal-hashvals */
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__u16 pad1; /* padding to match user-level */
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__u8 pad2; /* padding to match user-level */
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__u8 initted; /* T/F: cursor has been initialized */
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};
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/*========================================================================
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* Structure used to pass context around among the routines.
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*========================================================================*/
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/* void; state communicated via *context */
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typedef void (*put_listent_func_t)(struct xfs_attr_list_context *, int,
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unsigned char *, int, int);
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struct xfs_attr_list_context {
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struct xfs_trans *tp;
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struct xfs_inode *dp; /* inode */
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struct xfs_attrlist_cursor_kern cursor; /* position in list */
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void *buffer; /* output buffer */
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/*
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* Abort attribute list iteration if non-zero. Can be used to pass
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* error values to the xfs_attr_list caller.
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*/
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int seen_enough;
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bool allow_incomplete;
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ssize_t count; /* num used entries */
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int dupcnt; /* count dup hashvals seen */
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int bufsize; /* total buffer size */
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int firstu; /* first used byte in buffer */
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unsigned int attr_filter; /* XFS_ATTR_{ROOT,SECURE} */
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int resynch; /* T/F: resynch with cursor */
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put_listent_func_t put_listent; /* list output fmt function */
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int index; /* index into output buffer */
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};
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/*
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* ========================================================================
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* Structure used to pass context around among the delayed routines.
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* ========================================================================
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*/
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/*
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* Below is a state machine diagram for attr remove operations. The XFS_DAS_*
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* states indicate places where the function would return -EAGAIN, and then
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* immediately resume from after being called by the calling function. States
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* marked as a "subroutine state" indicate that they belong to a subroutine, and
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* so the calling function needs to pass them back to that subroutine to allow
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* it to finish where it left off. But they otherwise do not have a role in the
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* calling function other than just passing through.
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*
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* xfs_attr_remove_iter()
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* │
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* v
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* have attr to remove? ──n──> done
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* │
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* y
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* │
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* v
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* are we short form? ──y──> xfs_attr_shortform_remove ──> done
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* │
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* n
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* │
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* V
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* are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
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* │
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* n
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* │
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* V
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* ┌── need to setup state?
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* │ │
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* n y
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* │ │
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* │ v
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* │ find attr and get state
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* │ attr has remote blks? ──n─┐
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* │ │ v
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* │ │ find and invalidate
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* │ y the remote blocks.
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* │ │ mark attr incomplete
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* │ ├────────────────┘
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* └──────────┤
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* │
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* v
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* Have remote blks to remove? ───y─────┐
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* │ ^ remove the blks
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* │ │ │
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* │ │ v
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* │ XFS_DAS_RMTBLK <─n── done?
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* │ re-enter with │
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* │ one less blk to y
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* │ remove │
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* │ V
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* │ refill the state
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* n │
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* │ v
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* │ XFS_DAS_RM_NAME
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* │ │
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* ├─────────────────────────┘
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* │
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* v
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* remove leaf and
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* update hash with
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* xfs_attr_node_remove_cleanup
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* │
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* v
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* need to
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* shrink tree? ─n─┐
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* │ │
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* y │
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* │ │
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* v │
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* join leaf │
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* │ │
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* v │
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* XFS_DAS_RM_SHRINK │
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* │ │
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* v │
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* do the shrink │
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* │ │
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* v │
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* free state <──┘
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* │
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* v
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* done
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*
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*
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* Below is a state machine diagram for attr set operations.
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*
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* It seems the challenge with understanding this system comes from trying to
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* absorb the state machine all at once, when really one should only be looking
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* at it with in the context of a single function. Once a state sensitive
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* function is called, the idea is that it "takes ownership" of the
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* state machine. It isn't concerned with the states that may have belonged to
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* it's calling parent. Only the states relevant to itself or any other
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* subroutines there in. Once a calling function hands off the state machine to
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* a subroutine, it needs to respect the simple rule that it doesn't "own" the
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* state machine anymore, and it's the responsibility of that calling function
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* to propagate the -EAGAIN back up the call stack. Upon reentry, it is
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* committed to re-calling that subroutine until it returns something other than
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* -EAGAIN. Once that subroutine signals completion (by returning anything other
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* than -EAGAIN), the calling function can resume using the state machine.
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*
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* xfs_attr_set_iter()
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* │
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* v
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* ┌─y─ has an attr fork?
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* │ |
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* │ n
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* │ |
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* │ V
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* │ add a fork
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* │ │
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* └──────────┤
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* │
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* V
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* ┌─── is shortform?
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* │ │
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* │ y
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* │ │
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* │ V
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* │ xfs_attr_set_fmt
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* │ |
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* │ V
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* │ xfs_attr_try_sf_addname
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* │ │
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* │ V
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* │ had enough ──y──> done
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* │ space?
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* n │
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* │ n
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* │ │
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* │ V
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* │ transform to leaf
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* │ │
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* │ V
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* │ hold the leaf buffer
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* │ │
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* │ V
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* │ return -EAGAIN
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* │ Re-enter in
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* │ leaf form
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* │
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* └─> release leaf buffer
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* if needed
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* │
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* V
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* ┌───n── fork has
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* │ only 1 blk?
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* │ │
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* │ y
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* │ │
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* │ v
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* │ xfs_attr_leaf_try_add()
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* │ │
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* │ v
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* │ had enough ──────────────y─────────────┐
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* │ space? │
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* │ │ │
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* │ n │
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* │ │ │
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* │ v │
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* │ return -EAGAIN │
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* │ re-enter in │
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* │ node form │
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* │ │ │
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* └──────────┤ │
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* │ │
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* V │
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* xfs_attr_node_addname_find_attr │
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* determines if this │
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* is create or rename │
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* find space to store attr │
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* │ │
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* v │
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* xfs_attr_node_addname │
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* │ │
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* v │
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* fits in a node leaf? ────n─────┐ │
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* │ ^ v │
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* │ │ single leaf node? │
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* │ │ │ │ │
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* y │ y n │
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* │ │ │ │ │
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* v │ v v │
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* update │ grow the leaf split if │
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* hashvals └── return -EAGAIN needed │
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* │ retry leaf add │ │
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* │ on reentry │ │
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* ├────────────────────────────┘ │
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* │ │
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* v │
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* need to alloc │
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* ┌─y── or flip flag? │
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* │ │ │
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* │ n │
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* │ │ │
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* │ v │
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* │ done │
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* │ │
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* │ │
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* │ XFS_DAS_FOUND_LBLK <────────────────┘
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* │ │
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* │ V
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* │ xfs_attr_leaf_addname()
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* │ │
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* │ v
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* │ ┌──first time through?
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* │ │ │
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* │ │ y
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* │ │ │
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* │ n v
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* │ │ if we have rmt blks
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* │ │ find space for them
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* │ │ │
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* │ └──────────┤
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* │ │
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* │ v
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* │ still have
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* │ ┌─n─ blks to alloc? <──┐
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* │ │ │ │
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* │ │ y │
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* │ │ │ │
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* │ │ v │
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* │ │ alloc one blk │
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* │ │ return -EAGAIN ──┘
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* │ │ re-enter with one
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* │ │ less blk to alloc
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* │ │
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* │ │
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* │ └───> set the rmt
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* │ value
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* │ │
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* │ v
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* │ was this
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* │ a rename? ──n─┐
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* │ │ │
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* │ y │
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* │ │ │
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* │ v │
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* │ flip incomplete │
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* │ flag │
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* │ │ │
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* │ v │
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* │ XFS_DAS_FLIP_LFLAG │
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* │ │ │
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* │ v │
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* │ need to remove │
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* │ old bks? ──n──┤
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* │ │ │
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* │ y │
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* │ │ │
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* │ V │
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* │ remove │
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* │ ┌───> old blks │
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* │ │ │ │
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* │ XFS_DAS_RM_LBLK │ │
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* │ ^ │ │
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* │ │ v │
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* │ └──y── more to │
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* │ remove? │
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* │ │ │
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* │ n │
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* │ │ │
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* │ v │
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* │ XFS_DAS_RD_LEAF │
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* │ │ │
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* │ v │
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* │ remove leaf │
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* │ │ │
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* │ v │
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* │ shrink to sf │
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* │ if needed │
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* │ │ │
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* │ v │
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* │ done <──────┘
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* │
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* └──────> XFS_DAS_FOUND_NBLK
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* │
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* v
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* ┌─────n── need to
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* │ alloc blks?
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* │ │
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* │ y
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* │ │
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* │ v
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* │ find space
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* │ │
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* │ v
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* │ ┌─>XFS_DAS_ALLOC_NODE
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* │ │ │
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* │ │ v
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* │ │ alloc blk
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* │ │ │
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* │ │ v
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* │ └──y── need to alloc
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* │ more blocks?
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* │ │
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* │ n
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* │ │
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* │ v
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* │ set the rmt value
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* │ │
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* │ v
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* │ was this
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* └────────> a rename? ──n─┐
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* │ │
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* y │
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* │ │
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* v │
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* flip incomplete │
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* flag │
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* │ │
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* v │
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* XFS_DAS_FLIP_NFLAG │
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* │ │
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* v │
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* need to │
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* remove blks? ─n──┤
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* │ │
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* y │
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* │ │
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* v │
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* remove │
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* ┌────────> old blks │
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* │ │ │
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* XFS_DAS_RM_NBLK │ │
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* ^ │ │
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* │ v │
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* └──────y── more to │
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* remove │
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* │ │
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* n │
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* │ │
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* v │
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* XFS_DAS_CLR_FLAG │
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* │ │
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* v │
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* clear flags │
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* │ │
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* ├──────────┘
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* │
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* v
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* done
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*/
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/*
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* Enum values for xfs_delattr_context.da_state
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*
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* These values are used by delayed attribute operations to keep track of where
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* they were before they returned -EAGAIN. A return code of -EAGAIN signals the
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* calling function to roll the transaction, and then call the subroutine to
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* finish the operation. The enum is then used by the subroutine to jump back
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* to where it was and resume executing where it left off.
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*/
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enum xfs_delattr_state {
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XFS_DAS_UNINIT = 0, /* No state has been set yet */
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XFS_DAS_RMTBLK, /* Removing remote blks */
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XFS_DAS_RM_NAME, /* Remove attr name */
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XFS_DAS_RM_SHRINK, /* We are shrinking the tree */
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XFS_DAS_FOUND_LBLK, /* We found leaf blk for attr */
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XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
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XFS_DAS_FLIP_LFLAG, /* Flipped leaf INCOMPLETE attr flag */
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XFS_DAS_RM_LBLK, /* A rename is removing leaf blocks */
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XFS_DAS_RD_LEAF, /* Read in the new leaf */
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XFS_DAS_ALLOC_NODE, /* We are allocating node blocks */
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XFS_DAS_FLIP_NFLAG, /* Flipped node INCOMPLETE attr flag */
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XFS_DAS_RM_NBLK, /* A rename is removing node blocks */
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XFS_DAS_CLR_FLAG, /* Clear incomplete flag */
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};
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/*
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* Defines for xfs_delattr_context.flags
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*/
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#define XFS_DAC_DEFER_FINISH 0x01 /* finish the transaction */
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#define XFS_DAC_LEAF_ADDNAME_INIT 0x02 /* xfs_attr_leaf_addname init*/
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/*
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* Context used for keeping track of delayed attribute operations
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*/
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struct xfs_delattr_context {
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struct xfs_da_args *da_args;
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/* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
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struct xfs_bmbt_irec map;
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xfs_dablk_t lblkno;
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int blkcnt;
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/* Used in xfs_attr_node_removename to roll through removing blocks */
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struct xfs_da_state *da_state;
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/* Used to keep track of current state of delayed operation */
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unsigned int flags;
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enum xfs_delattr_state dela_state;
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};
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/*========================================================================
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* Function prototypes for the kernel.
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*========================================================================*/
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/*
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* Overall external interface routines.
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*/
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int xfs_attr_inactive(struct xfs_inode *dp);
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int xfs_attr_list_ilocked(struct xfs_attr_list_context *);
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int xfs_attr_list(struct xfs_attr_list_context *);
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int xfs_inode_hasattr(struct xfs_inode *ip);
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bool xfs_attr_is_leaf(struct xfs_inode *ip);
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int xfs_attr_get_ilocked(struct xfs_da_args *args);
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int xfs_attr_get(struct xfs_da_args *args);
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int xfs_attr_set(struct xfs_da_args *args);
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int xfs_attr_set_args(struct xfs_da_args *args);
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int xfs_has_attr(struct xfs_da_args *args);
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int xfs_attr_remove_args(struct xfs_da_args *args);
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int xfs_attr_remove_iter(struct xfs_delattr_context *dac);
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bool xfs_attr_namecheck(const void *name, size_t length);
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void xfs_delattr_context_init(struct xfs_delattr_context *dac,
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struct xfs_da_args *args);
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#endif /* __XFS_ATTR_H__ */
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