| Message ID | 20170524164150.9492-3-rgoldwyn@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed 24-05-17 11:41:42, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@suse.com> > > 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. > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> > Reviewed-by: Christoph Hellwig <hch@lst.de> Looks good. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > include/linux/fs.h | 2 ++ > mm/filemap.c | 33 +++++++++++++++++++++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index f53867140f43..dc0ab585cd56 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2517,6 +2517,8 @@ 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 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 --git a/mm/filemap.c b/mm/filemap.c > index 6f1be573a5e6..87aba7698584 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -376,6 +376,39 @@ 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 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) > { > -- > 2.12.0 >
diff --git a/include/linux/fs.h b/include/linux/fs.h index f53867140f43..dc0ab585cd56 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2517,6 +2517,8 @@ 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 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 --git a/mm/filemap.c b/mm/filemap.c index 6f1be573a5e6..87aba7698584 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -376,6 +376,39 @@ 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 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) {