diff options
author | Zach Brown <zach.brown@oracle.com> | 2005-12-15 14:28:17 -0800 |
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committer | Joel Becker <joel.becker@oracle.com> | 2006-01-03 11:45:42 -0800 |
commit | 994fc28c7b1e697ac56befe4aecabf23f0689f46 (patch) | |
tree | da36d162e9bd077e9b5be385b28e2db90475c263 /include/linux | |
parent | 7063fbf2261194f72ee75afca67b3b38b554b5fa (diff) | |
download | op-kernel-dev-994fc28c7b1e697ac56befe4aecabf23f0689f46.zip op-kernel-dev-994fc28c7b1e697ac56befe4aecabf23f0689f46.tar.gz |
[PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE
readpage(), prepare_write(), and commit_write() callers are updated to
understand the special return code AOP_TRUNCATED_PAGE in the style of
writepage() and WRITEPAGE_ACTIVATE. AOP_TRUNCATED_PAGE tells the caller that
the callee has unlocked the page and that the operation should be tried again
with a new page. OCFS2 uses this to detect and work around a lock inversion in
its aop methods. There should be no change in behaviour for methods that don't
return AOP_TRUNCATED_PAGE.
WRITEPAGE_ACTIVATE is also prepended with AOP_ for consistency and they are
made enums so that kerneldoc can be used to document their semantics.
Signed-off-by: Zach Brown <zach.brown@oracle.com>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/fs.h | 31 | ||||
-rw-r--r-- | include/linux/writeback.h | 6 |
2 files changed, 31 insertions, 6 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index cc35b6a..ed9a41a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -302,6 +302,37 @@ struct iattr { */ #include <linux/quota.h> +/** + * enum positive_aop_returns - aop return codes with specific semantics + * + * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has + * completed, that the page is still locked, and + * should be considered active. The VM uses this hint + * to return the page to the active list -- it won't + * be a candidate for writeback again in the near + * future. Other callers must be careful to unlock + * the page if they get this return. Returned by + * writepage(); + * + * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has + * unlocked it and the page might have been truncated. + * The caller should back up to acquiring a new page and + * trying again. The aop will be taking reasonable + * precautions not to livelock. If the caller held a page + * reference, it should drop it before retrying. Returned + * by readpage(), prepare_write(), and commit_write(). + * + * address_space_operation functions return these large constants to indicate + * special semantics to the caller. These are much larger than the bytes in a + * page to allow for functions that return the number of bytes operated on in a + * given page. + */ + +enum positive_aop_returns { + AOP_WRITEPAGE_ACTIVATE = 0x80000, + AOP_TRUNCATED_PAGE = 0x80001, +}; + /* * oh the beauties of C type declarations. */ diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 343d883..64a36ba 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -60,12 +60,6 @@ struct writeback_control { }; /* - * ->writepage() return values (make these much larger than a pagesize, in - * case some fs is returning number-of-bytes-written from writepage) - */ -#define WRITEPAGE_ACTIVATE 0x80000 /* IO was not started: activate page */ - -/* * fs/fs-writeback.c */ void writeback_inodes(struct writeback_control *wbc); |