On Sat, May 24, 2008 at 05:02:35PM -0700, Mark Fasheh wrote:
> 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,
>
Here is my updated patch that should address Andreas's and Chris's concerns.
I added ext2 support as well. Thank you,
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxx>
Index: linux-2.6/fs/ext3/file.c
===================================================================
--- linux-2.6.orig/fs/ext3/file.c
+++ linux-2.6/fs/ext3/file.c
@@ -134,5 +134,6 @@ const struct inode_operations ext3_file_
.removexattr = generic_removexattr,
#endif
.permission = ext3_permission,
+ .fiemap = ext3_fiemap,
};
Index: linux-2.6/fs/ext3/inode.c
===================================================================
--- linux-2.6.orig/fs/ext3/inode.c
+++ linux-2.6/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
*/
Index: linux-2.6/include/linux/ext3_fs.h
===================================================================
--- linux-2.6.orig/include/linux/ext3_fs.h
+++ linux-2.6/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,
Index: linux-2.6/fs/ioctl.c
===================================================================
--- linux-2.6.orig/fs/ioctl.c
+++ linux-2.6/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 +211,118 @@ 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;
+
+ 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 (!buffer_mapped(&tmp)) {
+ /*
+ * first hole after going past the EOF, this is our
+ * last extent
+ */
+ if (length <= 0) {
+ 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) {
+ 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 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)
{
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -1976,6 +1976,9 @@ extern int vfs_fstat(unsigned int, struc
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);
Index: linux-2.6/fs/ext2/ext2.h
===================================================================
--- linux-2.6.orig/fs/ext2/ext2.h
+++ linux-2.6/fs/ext2/ext2.h
@@ -133,6 +133,8 @@ extern void ext2_truncate (struct inode
extern int ext2_setattr (struct dentry *, struct iattr *);
extern void ext2_set_inode_flags(struct inode *inode);
extern void ext2_get_inode_flags(struct ext2_inode_info *);
+extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 len);
int __ext2_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata);
Index: linux-2.6/fs/ext2/file.c
===================================================================
--- linux-2.6.orig/fs/ext2/file.c
+++ linux-2.6/fs/ext2/file.c
@@ -86,4 +86,5 @@ const struct inode_operations ext2_file_
#endif
.setattr = ext2_setattr,
.permission = ext2_permission,
+ .fiemap = ext2_fiemap,
};
Index: linux-2.6/fs/ext2/inode.c
===================================================================
--- linux-2.6.orig/fs/ext2/inode.c
+++ linux-2.6/fs/ext2/inode.c
@@ -31,6 +31,7 @@
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
+#include <linux/fiemap.h>
#include "ext2.h"
#include "acl.h"
#include "xip.h"
@@ -704,6 +705,13 @@ int ext2_get_block(struct inode *inode,
}
+int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 len)
+{
+ return generic_block_fiemap(inode, fieinfo, start, len,
+ ext2_get_block);
+}
+
static int ext2_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, ext2_get_block, wbc);
--
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