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This patch lays out the foundation for using generic routines to manage processing items of message data. For simplicity, we'll start with just the trail portion of a message, because it stands alone and is only present for outgoing data. First some basic concepts. We'll use the term "data item" to represent one of the ceph_msg_data structures associated with a message. There are currently four of those, with single-letter field names p, l, b, and t. A data item is further broken into "pieces" which always lie in a single page. A data item will include a "cursor" that will track state as the memory defined by the item is consumed by sending data from or receiving data into it. We define three routines to manipulate a data item's cursor: the "init" routine; the "next" routine; and the "advance" routine. The "init" routine initializes the cursor so it points at the beginning of the first piece in the item. The "next" routine returns the page, page offset, and length (limited by both the page and item size) of the next unconsumed piece in the item. It also indicates to the caller whether the piece being returned is the last one in the data item. The "advance" routine consumes the requested number of bytes in the item (advancing the cursor). This is used to record the number of bytes from the current piece that were actually sent or received by the network code. It returns an indication of whether the result means the current piece has been fully consumed. This is used by the message send code to determine whether it should calculate the CRC for the next piece processed. The trail of a message is implemented as a ceph pagelist. The routines defined for it will be usable for non-trail pagelist data as well. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com> |
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| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
| keys | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| rxrpc | ||
| scsi | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| video | ||
| xen | ||
| Kbuild | ||