The patch titled
Subject: fs: introduce filemap_range_has_page()
has been added to the -mm tree. Its filename is
fs-introduce-filemap_range_has_page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-introduce-filemap_range_has_page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-introduce-filemap_range_has_page.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Subject: fs: introduce filemap_range_has_page()
filemap_range_has_page() return true if the file's mapping has a page
within the range mentioned. This function will be used to check if a
write() call will cause a writeback of previous writes.
Link: http://lkml.kernel.org/r/20170615160002.17233-3-rgoldwyn@xxxxxxx
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: Chris Mason <clm@xxxxxx>
Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Josef Bacik <jbacik@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/fs.h | 2 ++
mm/filemap.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff -puN include/linux/fs.h~fs-introduce-filemap_range_has_page include/linux/fs.h
--- a/include/linux/fs.h~fs-introduce-filemap_range_has_page
+++ a/include/linux/fs.h
@@ -2517,6 +2517,8 @@ extern int filemap_fdatawait(struct addr
extern void filemap_fdatawait_keep_errors(struct address_space *);
extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
loff_t lend);
+extern int filemap_range_has_page(struct address_space *, loff_t lstart,
+ loff_t lend);
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);
diff -puN mm/filemap.c~fs-introduce-filemap_range_has_page mm/filemap.c
--- a/mm/filemap.c~fs-introduce-filemap_range_has_page
+++ a/mm/filemap.c
@@ -376,6 +376,39 @@ int filemap_flush(struct address_space *
}
EXPORT_SYMBOL(filemap_flush);
+/**
+ * filemap_range_has_page - check if a page exists in range.
+ * @mapping: address space structure to wait for
+ * @start_byte: offset in bytes where the range starts
+ * @end_byte: offset in bytes where the range ends (inclusive)
+ *
+ * Find at least one page in the range supplied, usually used to check if
+ * direct writing in this range will trigger a writeback.
+ */
+int filemap_range_has_page(struct address_space *mapping,
+ loff_t start_byte, loff_t end_byte)
+{
+ pgoff_t index = start_byte >> PAGE_SHIFT;
+ pgoff_t end = end_byte >> PAGE_SHIFT;
+ struct pagevec pvec;
+ int ret;
+
+ if (end_byte < start_byte)
+ return 0;
+
+ if (mapping->nrpages == 0)
+ return 0;
+
+ pagevec_init(&pvec, 0);
+ ret = pagevec_lookup(&pvec, mapping, index, 1);
+ if (!ret)
+ return 0;
+ ret = (pvec.pages[0]->index <= end);
+ pagevec_release(&pvec);
+ return ret;
+}
+EXPORT_SYMBOL(filemap_range_has_page);
+
static int __filemap_fdatawait_range(struct address_space *mapping,
loff_t start_byte, loff_t end_byte)
{
_
Patches currently in -mm which might be from rgoldwyn@xxxxxxxx are
fs-separate-out-kiocb-flags-setup-based-on-rwf_-flags.patch
fs-introduce-filemap_range_has_page.patch
fs-use-rwf_-flags-for-aio-operations.patch
fs-introduce-rwf_nowait-and-fmode_aio_nowait.patch
fs-return-if-direct-write-will-trigger-writeback.patch
fs-introduce-iomap_nowait.patch
block-return-on-congested-block-device.patch
ext4-nowait-aio-support.patch
xfs-nowait-aio-support.patch
btrfs-nowait-aio-support.patch
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