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authorAndrew Morton <akpm@osdl.org>2006-03-24 03:18:04 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-24 07:33:25 -0800
commitebcf28e1c7a295f3321249dd235ad2e45938fdd9 (patch)
treefdd2e131e627af55d3741a7fafad0edaa61410c1 /include
parent469eb4d03878b676418f853011ebfb54ccf83a5e (diff)
[PATCH] fadvise(): write commands
Add two new linux-specific fadvise extensions(): LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file offsets `offset' and `offset+len'. Any pages which are currently under writeout are skipped, whether or not they are dirty. LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file offsets `offset' and `offset+len'. By combining these two operations the application may do several things: LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk. LINUX_FADV_WRITE_WAIT, LINUX_FADV_ASYNC_WRITE: push all of the currently dirty pages at the disk. LINUX_FADV_WRITE_WAIT, LINUX_FADV_ASYNC_WRITE, LINUX_FADV_WRITE_WAIT: push all of the currently dirty pages at the disk, wait until they have been written. It should be noted that none of these operations write out the file's metadata. So unless the application is strictly performing overwrites of already-instantiated disk blocks, there are no guarantees here that the data will be available after a crash. To complete this suite of operations I guess we should have a "sync file metadata only" operation. This gives applications access to all the building blocks needed for all sorts of sync operations. But sync-metadata doesn't fit well with the fadvise() interface. Probably it should be a new syscall: sys_fmetadatasync(). The patch also diddles with the meaning of `endbyte' in sys_fadvise64_64(). It is made to represent that last affected byte in the file (ie: it is inclusive). Generally, all these byterange and pagerange functions are inclusive so we can easily represent EOF with -1. As Ulrich notes, these two functions are somewhat abusive of the fadvise() concept, which appears to be "set the future policy for this fd". But these commands are a perfect fit with the fadvise() impementation, and several of the existing fadvise() commands are synchronous and don't affect future policy either. I think we can live with the slight incongruity. Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/fadvise.h6
-rw-r--r--include/linux/fs.h5
2 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/fadvise.h b/include/linux/fadvise.h
index e8e747139b9..b2913bba35d 100644
--- a/include/linux/fadvise.h
+++ b/include/linux/fadvise.h
@@ -18,4 +18,10 @@
#define POSIX_FADV_NOREUSE 5 /* Data will be accessed once. */
#endif
+/*
+ * Linux-specific fadvise() extensions:
+ */
+#define LINUX_FADV_ASYNC_WRITE 32 /* Start writeout on range */
+#define LINUX_FADV_WRITE_WAIT 33 /* Wait upon writeout to range */
+
#endif /* FADVISE_H_INCLUDED */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 65e6df247ea..0ad70c1e5e5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1473,6 +1473,11 @@ extern int filemap_fdatawait(struct address_space *);
extern int filemap_write_and_wait(struct address_space *mapping);
extern int filemap_write_and_wait_range(struct address_space *mapping,
loff_t lstart, loff_t lend);
+extern int wait_on_page_writeback_range(struct address_space *mapping,
+ pgoff_t start, pgoff_t end);
+extern int __filemap_fdatawrite_range(struct address_space *mapping,
+ loff_t start, loff_t end, int sync_mode);
+
extern void sync_supers(void);
extern void sync_filesystems(int wait);
extern void emergency_sync(void);