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| author | Goldwyn Rodrigues <rgoldwyn@suse.com> | 2017-06-20 07:05:41 -0500 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-06-20 07:12:03 -0600 |
| commit | 7fc9e4722435cd8459182c4975f48934f2bb1274 (patch) | |
| tree | 44a50b5cfa0379939111ef900f73b4c2657c83a4 | |
| parent | fdd2f5b7de2afaa931e5f7bad7bcda35d1f1b479 (diff) | |
| download | linux-7fc9e4722435cd8459182c4975f48934f2bb1274.tar.bz2 | |
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.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | include/linux/fs.h | 2 | ||||
| -rw-r--r-- | mm/filemap.c | 32 |
2 files changed, 34 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 96a1a1fa54a9..0d34f5b5a6b0 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2518,6 +2518,8 @@ extern int filemap_fdatawait(struct address_space *); extern void filemap_fdatawait_keep_errors(struct address_space *); extern int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend); +extern bool 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 --git a/mm/filemap.c b/mm/filemap.c index 6f1be573a5e6..9b39a2390b9e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -376,6 +376,38 @@ int filemap_flush(struct address_space *mapping) } EXPORT_SYMBOL(filemap_flush); +/** + * filemap_range_has_page - check if a page exists in range. + * @mapping: address space within which to check + * @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. + */ +bool 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; + bool ret; + + if (end_byte < start_byte) + return false; + + if (mapping->nrpages == 0) + return false; + + pagevec_init(&pvec, 0); + if (!pagevec_lookup(&pvec, mapping, index, 1)) + return false; + 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) { |