xfs: xfs_trans_alloc_empty
This is a partial cherry-pick of commit e89c041338
("xfs: implement the GETFSMAP ioctl"), which also adds this helper, and
a great example of why feature patches should be properly split into
their parts.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[hch: split from the larger patch for -stable]
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
parent
0e542792a0
commit
e40c145c02
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@ -262,6 +262,28 @@ xfs_trans_alloc(
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return 0;
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return 0;
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}
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}
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/*
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* Create an empty transaction with no reservation. This is a defensive
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* mechanism for routines that query metadata without actually modifying
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* them -- if the metadata being queried is somehow cross-linked (think a
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* btree block pointer that points higher in the tree), we risk deadlock.
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* However, blocks grabbed as part of a transaction can be re-grabbed.
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* The verifiers will notice the corrupt block and the operation will fail
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* back to userspace without deadlocking.
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*
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* Note the zero-length reservation; this transaction MUST be cancelled
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* without any dirty data.
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*/
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int
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xfs_trans_alloc_empty(
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struct xfs_mount *mp,
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struct xfs_trans **tpp)
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{
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struct xfs_trans_res resv = {0};
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return xfs_trans_alloc(mp, &resv, 0, 0, XFS_TRANS_NO_WRITECOUNT, tpp);
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}
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/*
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/*
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* Record the indicated change to the given field for application
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* Record the indicated change to the given field for application
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* to the file system's superblock when the transaction commits.
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* to the file system's superblock when the transaction commits.
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@ -159,6 +159,8 @@ typedef struct xfs_trans {
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int xfs_trans_alloc(struct xfs_mount *mp, struct xfs_trans_res *resp,
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int xfs_trans_alloc(struct xfs_mount *mp, struct xfs_trans_res *resp,
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uint blocks, uint rtextents, uint flags,
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uint blocks, uint rtextents, uint flags,
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struct xfs_trans **tpp);
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struct xfs_trans **tpp);
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int xfs_trans_alloc_empty(struct xfs_mount *mp,
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struct xfs_trans **tpp);
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void xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);
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void xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);
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struct xfs_buf *xfs_trans_get_buf_map(struct xfs_trans *tp,
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struct xfs_buf *xfs_trans_get_buf_map(struct xfs_trans *tp,
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