ping
On 10/18/2014 05:22 PM, Jan Chaloupka wrote:
As from upstream commit:
commit 3f31d07571eeea18a7d34db9af21d2285b807a17
Author: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Tue May 29 15:06:40 2012 -0700
mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE
Now tmpfs supports hole-punching via fallocate(), switch madvise_remove()
to use do_fallocate() instead of vmtruncate_range(): which extends
madvise(,,MADV_REMOVE) support from tmpfs to ext4, ocfs2 and xfs.
madvise(,,MADV_REMOVE) support was extended by ext4, ocfs2 and xfs.
bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1120294
Justification from Rafael Aquini:
Well, that code is committed in kernel since v3.5 (2012) and it surely is
the expected behaviour since. It seems to me that madvise(2) man page text
for MADV_REMOVE just got out-of-date in that regard.
This patch mentions this support in madvise.2 man page.
Reworded and corrected by Michael Kerrisk and Hugh Dickins. Thank you.
Signed-off-by: Jan Chaloupka <jchaloup@xxxxxxxxxx>
---
man2/madvise.2 | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/man2/madvise.2 b/man2/madvise.2
index 032ead7..b955864 100644
--- a/man2/madvise.2
+++ b/man2/madvise.2
@@ -101,11 +101,18 @@ without an underlying file.
.BR MADV_REMOVE " (since Linux 2.6.16)"
Free up a given range of pages
and its associated backing store.
-Currently,
-.\" 2.6.18-rc5
-only shmfs/tmpfs supports this; other filesystems return with the
-error
-.BR ENOSYS .
+Originally, only shmfs/tmpfs supported this; but since Linux 3.5,
+any filesystem which supports the
+.BR fallocate(2)
+mode
+.BR FALLOC_FL_PUNCH_HOLE
+also supports the
+.BR madvise(2)
+advice
+.BR MADV_REMOVE .
+Other filesystems return with the
+.BR EOPNOTSUPP
+error.
.\" Databases want to use this feature to drop a section of their
.\" bufferpool (shared memory segments) - without writing back to
.\" disk/swap space. This feature is also useful for supporting
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