[PATCH 4/8] iomap: move the SEEK_HOLE code into a separate file

Darrick J. Wong
2019-07-17T05:59:37Z

Move the SEEK_HOLE/SEEK_DATA code into a separate file so that we can
group related functions in a single file instead of having a single
enormous source file.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap.c | 201 --------------------------------------------------
fs/iomap/Makefile | 3 -
fs/iomap/seek.c | 214 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 216 insertions(+), 202 deletions(-)
create mode 100644 fs/iomap/seek.c

diff --git a/fs/iomap.c b/fs/iomap.c
index d14d75a97ab3..ad994c408cb8 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1149,207 +1149,6 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
}
EXPORT_SYMBOL_GPL(iomap_page_mkwrite);

-/*
- * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
- * Returns true if found and updates @lastoff to the offset in file.
- */
-static bool
-page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
- int whence)
-{
- const struct address_space_operations *ops = inode->i_mapping->a_ops;
- unsigned int bsize = i_blocksize(inode), off;
- bool seek_data = whence == SEEK_DATA;
- loff_t poff = page_offset(page);
-
- if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
- return false;
-
- if (*lastoff < poff) {
- /*
- * Last offset smaller than the start of the page means we found
- * a hole:
- */
- if (whence == SEEK_HOLE)
- return true;
- *lastoff = poff;
- }
-
- /*
- * Just check the page unless we can and should check block ranges:
- */
- if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
- return PageUptodate(page) == seek_data;
-
- lock_page(page);
- if (unlikely(page->mapping != inode->i_mapping))
- goto out_unlock_not_found;
-
- for (off = 0; off < PAGE_SIZE; off += bsize) {
- if (offset_in_page(*lastoff) >= off + bsize)
- continue;
- if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
- unlock_page(page);
- return true;
- }
- *lastoff = poff + off + bsize;
- }
-
-out_unlock_not_found:
- unlock_page(page);
- return false;
-}
-
-/*
- * Seek for SEEK_DATA / SEEK_HOLE in the page cache.
- *
- * Within unwritten extents, the page cache determines which parts are holes
- * and which are data: uptodate buffer heads count as data; everything else
- * counts as a hole.
- *
- * Returns the resulting offset on successs, and -ENOENT otherwise.
- */
-static loff_t
-page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
- int whence)
-{
- pgoff_t index = offset >> PAGE_SHIFT;
- pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
- loff_t lastoff = offset;
- struct pagevec pvec;
-
- if (length <= 0)
- return -ENOENT;
-
- pagevec_init(&pvec);
-
- do {
- unsigned nr_pages, i;
-
- nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
- end - 1);
- if (nr_pages == 0)
- break;
-
- for (i = 0; i < nr_pages; i++) {
- struct page *page = pvec.pages[i];
-
- if (page_seek_hole_data(inode, page, &lastoff, whence))
- goto check_range;
- lastoff = page_offset(page) + PAGE_SIZE;
- }
- pagevec_release(&pvec);
- } while (index < end);
-
- /* When no page at lastoff and we are not done, we found a hole. */
- if (whence != SEEK_HOLE)
- goto not_found;
-
-check_range:
- if (lastoff < offset + length)
- goto out;
-not_found:
- lastoff = -ENOENT;
-out:
- pagevec_release(&pvec);
- return lastoff;
-}
-
-
-static loff_t
-iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
- void *data, struct iomap *iomap)
-{
- switch (iomap->type) {
- case IOMAP_UNWRITTEN:
- offset = page_cache_seek_hole_data(inode, offset, length,
- SEEK_HOLE);
- if (offset < 0)
- return length;
- /* fall through */
- case IOMAP_HOLE:
- *(loff_t *)data = offset;
- return 0;
- default:
- return length;
- }
-}
-
-loff_t
-iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
-{
- loff_t size = i_size_read(inode);
- loff_t length = size - offset;
- loff_t ret;
-
- /* Nothing to be found before or beyond the end of the file. */
- if (offset < 0 || offset >= size)
- return -ENXIO;
-
- while (length > 0) {
- ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
- &offset, iomap_seek_hole_actor);
- if (ret < 0)
- return ret;
- if (ret == 0)
- break;
-
- offset += ret;
- length -= ret;
- }
-
- return offset;
-}
-EXPORT_SYMBOL_GPL(iomap_seek_hole);
-
-static loff_t
-iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
- void *data, struct iomap *iomap)
-{
- switch (iomap->type) {
- case IOMAP_HOLE:
- return length;
- case IOMAP_UNWRITTEN:
- offset = page_cache_seek_hole_data(inode, offset, length,
- SEEK_DATA);
- if (offset < 0)
- return length;
- /*FALLTHRU*/
- default:
- *(loff_t *)data = offset;
- return 0;
- }
-}
-
-loff_t
-iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
-{
- loff_t size = i_size_read(inode);
- loff_t length = size - offset;
- loff_t ret;
-
- /* Nothing to be found before or beyond the end of the file. */
- if (offset < 0 || offset >= size)
- return -ENXIO;
-
- while (length > 0) {
- ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
- &offset, iomap_seek_data_actor);
- if (ret < 0)
- return ret;
- if (ret == 0)
- break;
-
- offset += ret;
- length -= ret;
- }
-
- if (length <= 0)
- return -ENXIO;
- return offset;
-}
-EXPORT_SYMBOL_GPL(iomap_seek_data);
-
/*
* Private flags for iomap_dio, must not overlap with the public ones in
* iomap.h:
diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
index 44cef914020f..5dfe8b5cf330 100644
--- a/fs/iomap/Makefile
+++ b/fs/iomap/Makefile
@@ -6,6 +6,7 @@
obj-$(CONFIG_FS_IOMAP) += iomap.o

iomap-y += \
- fiemap.o
+ fiemap.o \
+ seek.o

iomap-$(CONFIG_SWAP) += swapfile.o
diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
new file mode 100644
index 000000000000..342b6d8ede67
--- /dev/null
+++ b/fs/iomap/seek.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 Red Hat, Inc.
+ * Copyright (c) 2016-2018 Christoph Hellwig.
+ */
+#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/iomap.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+
+#include "../internal.h"
+
+/*
+ * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
+ * Returns true if found and updates @lastoff to the offset in file.
+ */
+static bool
+page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
+ int whence)
+{
+ const struct address_space_operations *ops = inode->i_mapping->a_ops;
+ unsigned int bsize = i_blocksize(inode), off;
+ bool seek_data = whence == SEEK_DATA;
+ loff_t poff = page_offset(page);
+
+ if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
+ return false;
+
+ if (*lastoff < poff) {
+ /*
+ * Last offset smaller than the start of the page means we found
+ * a hole:
+ */
+ if (whence == SEEK_HOLE)
+ return true;
+ *lastoff = poff;
+ }
+
+ /*
+ * Just check the page unless we can and should check block ranges:
+ */
+ if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
+ return PageUptodate(page) == seek_data;
+
+ lock_page(page);
+ if (unlikely(page->mapping != inode->i_mapping))
+ goto out_unlock_not_found;
+
+ for (off = 0; off < PAGE_SIZE; off += bsize) {
+ if (offset_in_page(*lastoff) >= off + bsize)
+ continue;
+ if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
+ unlock_page(page);
+ return true;
+ }
+ *lastoff = poff + off + bsize;
+ }
+
+out_unlock_not_found:
+ unlock_page(page);
+ return false;
+}
+
+/*
+ * Seek for SEEK_DATA / SEEK_HOLE in the page cache.
+ *
+ * Within unwritten extents, the page cache determines which parts are holes
+ * and which are data: uptodate buffer heads count as data; everything else
+ * counts as a hole.
+ *
+ * Returns the resulting offset on successs, and -ENOENT otherwise.
+ */
+static loff_t
+page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
+ int whence)
+{
+ pgoff_t index = offset >> PAGE_SHIFT;
+ pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
+ loff_t lastoff = offset;
+ struct pagevec pvec;
+
+ if (length <= 0)
+ return -ENOENT;
+
+ pagevec_init(&pvec);
+
+ do {
+ unsigned nr_pages, i;
+
+ nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
+ end - 1);
+ if (nr_pages == 0)
+ break;
+
+ for (i = 0; i < nr_pages; i++) {
+ struct page *page = pvec.pages[i];
+
+ if (page_seek_hole_data(inode, page, &lastoff, whence))
+ goto check_range;
+ lastoff = page_offset(page) + PAGE_SIZE;
+ }
+ pagevec_release(&pvec);
+ } while (index < end);
+
+ /* When no page at lastoff and we are not done, we found a hole. */
+ if (whence != SEEK_HOLE)
+ goto not_found;
+
+check_range:
+ if (lastoff < offset + length)
+ goto out;
+not_found:
+ lastoff = -ENOENT;
+out:
+ pagevec_release(&pvec);
+ return lastoff;
+}
+
+
+static loff_t
+iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
+ void *data, struct iomap *iomap)
+{
+ switch (iomap->type) {
+ case IOMAP_UNWRITTEN:
+ offset = page_cache_seek_hole_data(inode, offset, length,
+ SEEK_HOLE);
+ if (offset < 0)
+ return length;
+ /* fall through */
+ case IOMAP_HOLE:
+ *(loff_t *)data = offset;
+ return 0;
+ default:
+ return length;
+ }
+}
+
+loff_t
+iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
+{
+ loff_t size = i_size_read(inode);
+ loff_t length = size - offset;
+ loff_t ret;
+
+ /* Nothing to be found before or beyond the end of the file. */
+ if (offset < 0 || offset >= size)
+ return -ENXIO;
+
+ while (length > 0) {
+ ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
+ &offset, iomap_seek_hole_actor);
+ if (ret < 0)
+ return ret;
+ if (ret == 0)
+ break;
+
+ offset += ret;
+ length -= ret;
+ }
+
+ return offset;
+}
+EXPORT_SYMBOL_GPL(iomap_seek_hole);
+
+static loff_t
+iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
+ void *data, struct iomap *iomap)
+{
+ switch (iomap->type) {
+ case IOMAP_HOLE:
+ return length;
+ case IOMAP_UNWRITTEN:
+ offset = page_cache_seek_hole_data(inode, offset, length,
+ SEEK_DATA);
+ if (offset < 0)
+ return length;
+ /*FALLTHRU*/
+ default:
+ *(loff_t *)data = offset;
+ return 0;
+ }
+}
+
+loff_t
+iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
+{
+ loff_t size = i_size_read(inode);
+ loff_t length = size - offset;
+ loff_t ret;
+
+ /* Nothing to be found before or beyond the end of the file. */
+ if (offset < 0 || offset >= size)
+ return -ENXIO;
+
+ while (length > 0) {
+ ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
+ &offset, iomap_seek_data_actor);
+ if (ret < 0)
+ return ret;
+ if (ret == 0)
+ break;
+
+ offset += ret;
+ length -= ret;
+ }
+
+ if (length <= 0)
+ return -ENXIO;
+ return offset;
+}
+EXPORT_SYMBOL_GPL(iomap_seek_data);