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author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-12 14:13:23 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-12 14:13:23 -0800 |
commit | 3e12cefbe143b4947171ff92dd50024c4841e291 (patch) | |
tree | f58ec23a4092576ed08843cca5f5443a32106bd1 /Documentation/filesystems | |
parent | 6bec0035286119eefc32a5b1102127e6a4032cb2 (diff) | |
parent | d427e3c82ef4fc5fbb22c0cef0b040e6767b1028 (diff) | |
download | linux-stable-3e12cefbe143b4947171ff92dd50024c4841e291.tar.gz linux-stable-3e12cefbe143b4947171ff92dd50024c4841e291.tar.bz2 linux-stable-3e12cefbe143b4947171ff92dd50024c4841e291.zip |
Merge branch 'for-3.20/core' of git://git.kernel.dk/linux-block
Pull core block IO changes from Jens Axboe:
"This contains:
- A series from Christoph that cleans up and refactors various parts
of the REQ_BLOCK_PC handling. Contributions in that series from
Dongsu Park and Kent Overstreet as well.
- CFQ:
- A bug fix for cfq for realtime IO scheduling from Jeff Moyer.
- A stable patch fixing a potential crash in CFQ in OOM
situations. From Konstantin Khlebnikov.
- blk-mq:
- Add support for tag allocation policies, from Shaohua. This is
a prep patch enabling libata (and other SCSI parts) to use the
blk-mq tagging, instead of rolling their own.
- Various little tweaks from Keith and Mike, in preparation for
DM blk-mq support.
- Minor little fixes or tweaks from me.
- A double free error fix from Tony Battersby.
- The partition 4k issue fixes from Matthew and Boaz.
- Add support for zero+unprovision for blkdev_issue_zeroout() from
Martin"
* 'for-3.20/core' of git://git.kernel.dk/linux-block: (27 commits)
block: remove unused function blk_bio_map_sg
block: handle the null_mapped flag correctly in blk_rq_map_user_iov
blk-mq: fix double-free in error path
block: prevent request-to-request merging with gaps if not allowed
blk-mq: make blk_mq_run_queues() static
dm: fix multipath regression due to initializing wrong request
cfq-iosched: handle failure of cfq group allocation
block: Quiesce zeroout wrapper
block: rewrite and split __bio_copy_iov()
block: merge __bio_map_user_iov into bio_map_user_iov
block: merge __bio_map_kern into bio_map_kern
block: pass iov_iter to the BLOCK_PC mapping functions
block: add a helper to free bio bounce buffer pages
block: use blk_rq_map_user_iov to implement blk_rq_map_user
block: simplify bio_map_kern
block: mark blk-mq devices as stackable
block: keep established cmd_flags when cloning into a blk-mq request
block: add blk-mq support to blk_insert_cloned_request()
block: require blk_rq_prep_clone() be given an initialized clone request
blk-mq: add tag allocation policy
...
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r-- | Documentation/filesystems/xip.txt | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/Documentation/filesystems/xip.txt b/Documentation/filesystems/xip.txt index 0466ee569278..b77472949ede 100644 --- a/Documentation/filesystems/xip.txt +++ b/Documentation/filesystems/xip.txt @@ -28,12 +28,15 @@ Implementation Execute-in-place is implemented in three steps: block device operation, address space operation, and file operations. -A block device operation named direct_access is used to retrieve a -reference (pointer) to a block on-disk. The reference is supposed to be -cpu-addressable, physical address and remain valid until the release operation -is performed. A struct block_device reference is used to address the device, -and a sector_t argument is used to identify the individual block. As an -alternative, memory technology devices can be used for this. +A block device operation named direct_access is used to translate the +block device sector number to a page frame number (pfn) that identifies +the physical page for the memory. It also returns a kernel virtual +address that can be used to access the memory. + +The direct_access method takes a 'size' parameter that indicates the +number of bytes being requested. The function should return the number +of bytes that can be contiguously accessed at that offset. It may also +return a negative errno if an error occurs. The block device operation is optional, these block devices support it as of today: |