[PATCH v5 0/10] fs: Introduce new flag(FALLOC_FL_COLLAPSE_RANGE) for fallocate

Namjae Jeon
2014-02-18T16:37:46Z

From: Namjae Jeon <namjae.jeon@samsung.com>

This patch series is in response of the following post:
http://lwn.net/Articles/556136/
"ext4: introduce two new ioctls"

Dave chinner suggested that truncate_block_range
(which was one of the ioctls name) should be an fallocate operation
and not any fs specific ioctl, hence we add this functionality to fallocate.

This patch series introduces new flag FALLOC_FL_COLLAPSE_RANGE for fallocate
and implements it for XFS and Ext4.

The semantics of this flag are following:
1) It collapses the range lying between offset and length by removing any data
blocks which are present in this range and than updates all the logical
offsets of extents beyond "offset + len" to nullify the hole created by
removing blocks. In short, it does not leave a hole.
2) It should be used exclusively. No other fallocate flag in combination.
3) Offset and length supplied to fallocate should be fs block size aligned
in case of xfs and ext4.
4) Collaspe range does not work beyond i_size.

This new functionality of collapsing range could be used by media editing tools
which does non linear editing to quickly purge and edit parts of a media file.
This will immensely improve the performance of these operations.
The limitation of fs block size aligned offsets can be easily handled
by media codecs which are encapsulated in a conatiner as they have to
just change the offset to next keyframe value to match the proper alignment.

Namjae Jeon (10):
fs: Add new flag(FALLOC_FL_COLLAPSE_RANGE) for fallocate
xfs: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate
ext4: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate
xfsprog: xfsio: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate
xfstest: shared/001: Standard collapse range tests
xfstest: shared/002: Delayed allocation collapse range
xfstest: shared/003: Multi collapse range tests
xfstest: shared/004: Delayed allocation multi collapse
xfstest: shared/005: Test multiple fallocate collapse
manpage: update FALLOC_FL_COLLAPSE_RANGE flag in fallocate
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1.7.11-rc0