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[PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE

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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>
This commit is contained in:
Zach Brown
2005-12-15 14:28:17 -08:00
committed by Joel Becker
parent 7063fbf226
commit 994fc28c7b
9 changed files with 113 additions and 45 deletions
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23
drivers/block/loop.c
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@@ -213,7 +213,7 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
struct address_space_operations *aops = mapping->a_ops;
pgoff_t index;
unsigned offset, bv_offs;
int len, ret = 0;
int len, ret;
down(&mapping->host->i_sem);
index = pos >> PAGE_CACHE_SHIFT;
@@ -232,9 +232,15 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
page = grab_cache_page(mapping, index);
if (unlikely(!page))
goto fail;
if (unlikely(aops->prepare_write(file, page, offset,
offset + size)))
ret = aops->prepare_write(file, page, offset,
offset + size);
if (unlikely(ret)) {
if (ret == AOP_TRUNCATED_PAGE) {
page_cache_release(page);
continue;
}
goto unlock;
}
transfer_result = lo_do_transfer(lo, WRITE, page, offset,
bvec->bv_page, bv_offs, size, IV);
if (unlikely(transfer_result)) {
@@ -251,9 +257,15 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
kunmap_atomic(kaddr, KM_USER0);
}
flush_dcache_page(page);
if (unlikely(aops->commit_write(file, page, offset,
offset + size)))
ret = aops->commit_write(file, page, offset,
offset + size);
if (unlikely(ret)) {
if (ret == AOP_TRUNCATED_PAGE) {
page_cache_release(page);
continue;
}
goto unlock;
}
if (unlikely(transfer_result))
goto unlock;
bv_offs += size;
@@ -264,6 +276,7 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
unlock_page(page);
page_cache_release(page);
}
ret = 0;
out:
up(&mapping->host->i_sem);
return ret;