From: Josef Bacik <jbacik@xxxxxxxxxx>
Here is my updated generic block based fiemap implementation with the fixes that
Andreas suggested. Basically any block based fs (this patch includes ext3) just
has to declare its own fiemap() function and then call this generic function
with its own get_block_t. This works well for block based filesystems that will
map multiple contiguous blocks at one time, but will work for filesystems that
only map one block at a time, you will just end up with an "extent" for each
block. One gotcha is this will not play nicely where there is hole+data after
the EOF. This function will assume its hit the end of the data as soon as it
hits a hole after the EOF, so if there is any data past that it will not pick
that up. AFAIK no block based fs does this anyway, but its in the comments of
the function anyway just in case. Thanks much,
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxx>
---
fs/ext3/file.c | 1 +
fs/ext3/inode.c | 8 +++
fs/ioctl.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/ext3_fs.h | 2 +
include/linux/fs.h | 3 +
5 files changed, 142 insertions(+), 0 deletions(-)
diff --git a/fs/ext3/file.c b/fs/ext3/file.c
index acc4913..3be1e06 100644
--- a/fs/ext3/file.c
+++ b/fs/ext3/file.c
@@ -134,5 +134,6 @@ const struct inode_operations ext3_file_inode_operations = {
.removexattr = generic_removexattr,
#endif
.permission = ext3_permission,
+ .fiemap = ext3_fiemap,
};
diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 6ae4ecf..878b6da 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -36,6 +36,7 @@
#include <linux/mpage.h>
#include <linux/uio.h>
#include <linux/bio.h>
+#include <linux/fiemap.h>
#include "xattr.h"
#include "acl.h"
@@ -981,6 +982,13 @@ out:
return ret;
}
+int ext3_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 len)
+{
+ return generic_block_fiemap(inode, fieinfo, start, len,
+ ext3_get_block);
+}
+
/*
* `handle' can be NULL if create is zero
*/
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 405bbcb..dbefd3b 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -13,6 +13,8 @@
#include <linux/security.h>
#include <linux/module.h>
#include <linux/uaccess.h>
+#include <linux/writeback.h>
+#include <linux/buffer_head.h>
#include <asm/ioctls.h>
@@ -209,6 +211,132 @@ out_bad_flags:
return -EBADR;
}
+#define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
+#define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
+
+/*
+ * @inode - the inode to map
+ * @arg - the pointer to userspace where we copy everything to
+ * @get_block - the fs's get_block function
+ *
+ * This does FIEMAP for block based inodes. Basically it will just loop
+ * through get_block until we hit the number of extents we want to map, or we
+ * go past the end of the file and hit a hole.
+ *
+ * If it is possible to have holes and data past EOF then please don't use this
+ * function, it will do wrong things.
+ */
+int generic_block_fiemap(struct inode *inode,
+ struct fiemap_extent_info *fieinfo, u64 start,
+ u64 len, get_block_t *get_block)
+{
+ struct buffer_head tmp;
+ unsigned int start_blk;
+ long long length = 0, map_len = 0;
+ u64 logical = 0, phys = 0, size = 0;
+ u32 flags = 0;
+ int ret = 0;
+ int just_count = fieinfo->fi_flags & FIEMAP_FLAG_NUM_EXTENTS;
+
+ start_blk = logical_to_blk(inode, start);
+
+ /* guard against change */
+ mutex_lock(&inode->i_mutex);
+
+ length = (long long)min_t(u64, len, i_size_read(inode));
+ map_len = length;
+
+ do {
+ /*
+ * we set b_size to the total size we want so it will map as
+ * many contiguous blocks as possible at once
+ */
+ memset(&tmp, 0, sizeof(struct buffer_head));
+ tmp.b_size = map_len;
+
+ ret = get_block(inode, start_blk, &tmp, 0);
+ if (ret)
+ break;
+
+ /* HOLE */
+ if (!tmp.b_blocknr) {
+ /*
+ * first hole after going past the EOF, this is our
+ * last extent
+ */
+ if (length <= 0) {
+ if (just_count) {
+ fieinfo->fi_extents_mapped++;
+ break;
+ }
+
+ flags = FIEMAP_EXTENT_LAST;
+ ret = fiemap_fill_next_extent(fieinfo, logical,
+ phys, size,
+ flags, 0);
+ break;
+ }
+
+ length -= blk_to_logical(inode, 1);
+
+ /* if we have holes up to/past EOF then we're done */
+ if (length <= 0)
+ break;
+
+ start_blk++;
+ } else {
+ if (length <= 0 && size && !just_count) {
+ ret = fiemap_fill_next_extent(fieinfo, logical,
+ phys, size,
+ flags, 0);
+ if (ret)
+ break;
+ }
+
+ logical = blk_to_logical(inode, start_blk);
+ phys = blk_to_logical(inode, tmp.b_blocknr);
+ size = tmp.b_size;
+ flags = 0;
+
+ length -= tmp.b_size;
+ start_blk += logical_to_blk(inode, size);
+
+ if (just_count) {
+ fieinfo->fi_extents_mapped++;
+ if (fieinfo->fi_extents_mapped ==
+ fieinfo->fi_extents_max)
+ break;
+ continue;
+ }
+
+ /*
+ * if we are past the EOF we need to loop again to see
+ * if there is a hole so we can mark this extent as the
+ * last one, and if not keep mapping things until we
+ * find a hole, or we run out of slots in the extent
+ * array
+ */
+ if (length <= 0)
+ continue;
+
+ ret = fiemap_fill_next_extent(fieinfo, logical, phys,
+ size, flags, 0);
+ if (ret)
+ break;
+ }
+ cond_resched();
+ } while (1);
+
+ mutex_unlock(&inode->i_mutex);
+
+ /* if ret is 1 then we just hit the end of the extent array */
+ if (ret == 1)
+ ret = 0;
+
+ return ret;
+}
+EXPORT_SYMBOL(generic_block_fiemap);
+
static int file_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
index 36c5403..2dc0dbb 100644
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -836,6 +836,8 @@ extern void ext3_truncate (struct inode *);
extern void ext3_set_inode_flags(struct inode *);
extern void ext3_get_inode_flags(struct ext3_inode_info *);
extern void ext3_set_aops(struct inode *inode);
+extern int ext3_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 len);
/* ioctl.c */
extern int ext3_ioctl (struct inode *, struct file *, unsigned int,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ed90393..5945136 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1976,6 +1976,9 @@ extern int vfs_fstat(unsigned int, struct kstat *);
extern int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
unsigned long arg);
+extern int generic_block_fiemap(struct inode *inode,
+ struct fiemap_extent_info *fieinfo, u64 start,
+ u64 len, get_block_t *get_block);
extern void get_filesystem(struct file_system_type *fs);
extern void put_filesystem(struct file_system_type *fs);
--
1.5.4.1
--
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