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-rw-r--r--fs/xfs/libxfs/xfs_attr.h403
1 files changed, 403 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
index 2b1f61987a9d..8de5d1d2733e 100644
--- a/fs/xfs/libxfs/xfs_attr.h
+++ b/fs/xfs/libxfs/xfs_attr.h
@@ -74,6 +74,406 @@ struct xfs_attr_list_context {
};
+/*
+ * ========================================================================
+ * 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_delattr_context.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 */
+ XFS_DAS_RMTBLK, /* Removing remote blks */
+ XFS_DAS_RM_NAME, /* Remove attr name */
+ XFS_DAS_RM_SHRINK, /* We are shrinking the tree */
+ XFS_DAS_FOUND_LBLK, /* We found leaf blk for attr */
+ XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
+ XFS_DAS_FLIP_LFLAG, /* Flipped leaf INCOMPLETE attr flag */
+ XFS_DAS_RM_LBLK, /* A rename is removing leaf blocks */
+ XFS_DAS_RD_LEAF, /* Read in the new leaf */
+ XFS_DAS_ALLOC_NODE, /* We are allocating node blocks */
+ XFS_DAS_FLIP_NFLAG, /* Flipped node INCOMPLETE attr flag */
+ XFS_DAS_RM_NBLK, /* A rename is removing node blocks */
+ XFS_DAS_CLR_FLAG, /* Clear incomplete flag */
+};
+
+/*
+ * Defines for xfs_delattr_context.flags
+ */
+#define XFS_DAC_DEFER_FINISH 0x01 /* finish the transaction */
+#define XFS_DAC_LEAF_ADDNAME_INIT 0x02 /* xfs_attr_leaf_addname init*/
+
+/*
+ * Context used for keeping track of delayed attribute operations
+ */
+struct xfs_delattr_context {
+ struct xfs_da_args *da_args;
+
+ /* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
+ struct xfs_bmbt_irec map;
+ xfs_dablk_t lblkno;
+ int blkcnt;
+
+ /* Used in xfs_attr_node_removename to roll through removing blocks */
+ struct xfs_da_state *da_state;
+
+ /* Used to keep track of current state of delayed operation */
+ unsigned int flags;
+ enum xfs_delattr_state dela_state;
+};
+
/*========================================================================
* Function prototypes for the kernel.
*========================================================================*/
@@ -92,6 +492,9 @@ int xfs_attr_set(struct xfs_da_args *args);
int xfs_attr_set_args(struct xfs_da_args *args);
int xfs_has_attr(struct xfs_da_args *args);
int xfs_attr_remove_args(struct xfs_da_args *args);
+int xfs_attr_remove_iter(struct xfs_delattr_context *dac);
bool xfs_attr_namecheck(const void *name, size_t length);
+void xfs_delattr_context_init(struct xfs_delattr_context *dac,
+ struct xfs_da_args *args);
#endif /* __XFS_ATTR_H__ */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.