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Message-Id: <20170627214828.1029-5-hch@lst.de>
Date: Tue, 27 Jun 2017 14:48:26 -0700
From: Christoph Hellwig <hch@....de>
To: Andreas Gruenbacher <agruenba@...hat.com>
Cc: Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCH 4/6] vfs: Add iomap_seek_hole and iomap_seek_data helpers
From: Andreas Gruenbacher <agruenba@...hat.com>
Filesystems can use this for implementing lseek SEEK_HOLE / SEEK_DATA
support via iomap.
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
[hch: split functions, coding style cleanups]
Signed-off-by: Christoph Hellwig <hch@....de>
---
fs/iomap.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/iomap.h | 4 +++
2 files changed, 102 insertions(+)
diff --git a/fs/iomap.c b/fs/iomap.c
index 4b10892967a5..c90cda33994b 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -584,6 +584,104 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
}
EXPORT_SYMBOL_GPL(iomap_fiemap);
+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 beyond the end of the file. */
+ if (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;
+ }
+
+ /* The last segment can extend beyond the end of the file. */
+ if (length <= 0)
+ return min(offset, size);
+ 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 beyond the end of the file. */
+ if (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;
+ }
+
+ /* There is an implicit hole at the end of the file. */
+ 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/include/linux/iomap.h b/include/linux/iomap.h
index f753e788da31..8a03f5dcd89b 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -83,6 +83,10 @@ int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops);
int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
loff_t start, loff_t len, const struct iomap_ops *ops);
+loff_t iomap_seek_hole(struct inode *inode, loff_t offset,
+ const struct iomap_ops *ops);
+loff_t iomap_seek_data(struct inode *inode, loff_t offset,
+ const struct iomap_ops *ops);
/*
* Flags for direct I/O ->end_io:
--
2.11.0
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