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Message-ID: <47EA6F55.2040407@redhat.com>
Date: Wed, 26 Mar 2008 10:44:21 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH 3/3] ext4 fiemap implementation
Here is ext4_fiemap() itself. This still needs a bit of testing & work,
but is correct for most file layouts.... I still hit occasional problems
with interesting mappings such as sparse/preallocated/etc.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
... again also probably signed-off-by Andreas & Kalpak as well.
-Eric
Index: linux-2.6.25-rc1/fs/ext4/extents.c
===================================================================
--- linux-2.6.25-rc1.orig/fs/ext4/extents.c
+++ linux-2.6.25-rc1/fs/ext4/extents.c
@@ -42,6 +42,7 @@
#include <linux/slab.h>
#include <linux/falloc.h>
#include <linux/ext4_fs_extents.h>
+#include <linux/fiemap.h>
#include <asm/uaccess.h>
@@ -1665,7 +1666,7 @@ int ext4_ext_walk_space(struct inode *in
}
BUG_ON(cbex.ec_len == 0);
- err = func(inode, path, &cbex, cbdata);
+ err = func(inode, path, &cbex, ex, cbdata);
ext4_ext_drop_refs(path);
if (err < 0)
@@ -3000,3 +3001,183 @@ retry:
mutex_unlock(&inode->i_mutex);
return ret > 0 ? ret2 : ret;
}
+
+struct fiemap_internal {
+ struct fiemap *fiemap_s;
+ struct fiemap_extent fm_extent;
+ size_t tot_mapping_len;
+ char *cur_ext_ptr;
+ int current_extent;
+ int err;
+};
+
+/*
+ * Callback function called for each extent to gather FIEMAP information.
+ */
+int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
+ struct ext4_ext_cache *newex, struct ext4_extent *ex,
+ void *data)
+{
+ struct fiemap_internal *fiemap_i = data;
+ struct fiemap *fiemap_s = fiemap_i->fiemap_s;
+ struct fiemap_extent *fm_extent = &fiemap_i->fm_extent;
+ int current_extent = fiemap_i->current_extent;
+ unsigned long blksize_bits = inode->i_sb->s_blocksize_bits;
+
+ /*
+ * ext4_ext_walk_space returns a hole for extents that have not been
+ * allocated yet.
+ */
+ if (((u64)(newex->ec_block + newex->ec_len) << blksize_bits >=
+ inode->i_size) && newex->ec_type == EXT4_EXT_CACHE_GAP) {
+ if (((u64)newex->ec_block << blksize_bits) < inode->i_size)
+ newex->ec_len = (inode->i_size - ((u64)newex->ec_block<<
+ blksize_bits)) >> blksize_bits;
+ else
+ return EXT_BREAK;
+ }
+
+ /*
+ * We only need to return number of extents and total length of mapping
+ */
+ if (fiemap_s->fm_flags & FIEMAP_FLAG_NUM_EXTENTS) {
+ fiemap_i->tot_mapping_len += ((__u64)newex->ec_len <<
+ blksize_bits);
+ goto count_extents;
+ }
+
+ if (current_extent >= fiemap_s->fm_extent_count)
+ return EXT_BREAK;
+
+ /* caller's start should be set to the start of the first extent (or hole...?) */
+ if (newex->ec_block << blksize_bits < fiemap_s->fm_start)
+ fiemap_s->fm_start = newex->ec_block << blksize_bits;
+
+ memset(fm_extent, 0, sizeof(*fm_extent));
+ fm_extent->fe_offset = (__u64)newex->ec_start << blksize_bits;
+ fm_extent->fe_length = (__u64)newex->ec_len << blksize_bits;
+ fiemap_i->tot_mapping_len += fm_extent->fe_length; /* move this above the goto? */
+
+ if (newex->ec_type == EXT4_EXT_CACHE_GAP)
+ fm_extent->fe_flags |= FIEMAP_EXTENT_HOLE;
+ else if (ex && ext4_ext_is_uninitialized(ex))
+ fm_extent->fe_flags |= FIEMAP_EXTENT_UNWRITTEN;
+
+ /*
+ * Mark this fiemap_extent as FIEMAP_EXTENT_EOF if it's past the end
+ * of file.
+ */
+ /* block + len to bytes... >= size? check off by one */
+ if ((u64)(newex->ec_block + newex->ec_len) << blksize_bits >=
+ inode->i_size)
+ fm_extent->fe_flags |= FIEMAP_EXTENT_EOF;
+ // XXX ERS HACK AROUND _LAST problem
+ //fm_extent->fe_flags |= (FIEMAP_EXTENT_EOF|FIEMAP_EXTENT_LAST);
+
+ if (!copy_to_user(fiemap_i->cur_ext_ptr, fm_extent,
+ sizeof(struct fiemap_extent))) {
+ /* c_t_u succeeded, advance current exent ptr to next */
+ fiemap_i->cur_ext_ptr += sizeof(struct fiemap_extent);
+ } else {
+ fiemap_i->err = -EFAULT;
+ return EXT_BREAK;
+ }
+
+count_extents:
+ /*
+ * Don't count holes when only returning number of extents
+ * XXX ERS hm, ok if that's how it's defined...
+ */
+ if (!((fiemap_s->fm_flags & FIEMAP_FLAG_NUM_EXTENTS) &&
+ (newex->ec_type == EXT4_EXT_CACHE_GAP)))
+ fiemap_i->current_extent++; /* hmm why? oh, advance count */
+
+ /*
+ * Stop if we are beyond requested mapping size but return complete last
+ * extent.
+ */
+
+ /* is this extent's last byte >= length of mapping?
+ * (XXX really? not start+length of mapping? */
+ if ((u64)(newex->ec_block + newex->ec_len) << blksize_bits >=
+ fiemap_s->fm_length)
+ return EXT_BREAK;
+
+ return EXT_CONTINUE;
+}
+
+int ext4_fiemap(struct inode *inode, unsigned long arg)
+{
+ struct fiemap *fiemap_s;
+ struct fiemap_internal fiemap_i;
+ struct fiemap_extent *last_extent;
+ ext4_lblk_t start_blk;
+ int fm_extent_size = sizeof(struct fiemap_extent);
+ int err = 0;
+
+ /* could use getblock here for non-extent files? */
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+ return -EOPNOTSUPP;
+
+ fiemap_s = kmalloc(sizeof(*fiemap_s), GFP_KERNEL);
+ if (fiemap_s == NULL)
+ return -ENOMEM;
+
+ if (copy_from_user(fiemap_s, (struct fiemap __user *)arg,
+ sizeof(*fiemap_s))) {
+ err = -EFAULT;
+ goto out_free;
+ }
+
+ /* bail on unsupported flags for this fs */
+ if (fiemap_s->fm_flags & EXT4_FIEMAP_FLAG_INCOMPAT_UNSUPP) {
+ err = -EOPNOTSUPP;
+ goto out_free;
+ }
+
+ start_blk = fiemap_s->fm_start >> inode->i_sb->s_blocksize_bits;
+ fiemap_i.fiemap_s = fiemap_s;
+ fiemap_i.tot_mapping_len = 0;
+ fiemap_i.cur_ext_ptr = (char *)(arg + sizeof(*fiemap_s));
+ fiemap_i.current_extent = 0;
+ fiemap_i.err = 0;
+
+ start_blk = fiemap_s->fm_start >> inode->i_sb->s_blocksize_bits;
+
+ /*
+ * Walk the extent tree gathering extent information
+ */
+ down_write(&EXT4_I(inode)->i_data_sem);
+ err = ext4_ext_walk_space(inode, start_blk, EXT_MAX_BLOCK - start_blk,
+ ext4_ext_fiemap_cb, &fiemap_i);
+ up_write(&EXT4_I(inode)->i_data_sem);
+ if (err)
+ goto out_free;
+
+ fiemap_s->fm_extent_count = fiemap_i.current_extent;
+ fiemap_s->fm_length = fiemap_i.tot_mapping_len;
+ /*
+ * Mark last extent as EXTENT_LAST and copy the extent to userspace.`
+ * XXX ERS fixme, this isn't always working.
+ */
+ if (fiemap_i.current_extent != 0 &&
+ fiemap_i.current_extent < fiemap_s->fm_extent_count &&
+ !(fiemap_s->fm_flags & FIEMAP_FLAG_NUM_EXTENTS)) {
+ char *dest;
+
+ last_extent = &fiemap_i.fm_extent;
+ last_extent->fe_flags |= FIEMAP_EXTENT_LAST;
+ dest = (char *)arg + sizeof(*fiemap_s) + fm_extent_size *
+ (fiemap_s->fm_extent_count - 1);
+ err = copy_to_user(dest, last_extent, fm_extent_size);
+ if (err)
+ goto out_free;
+ }
+
+ err = copy_to_user((void *)arg, fiemap_s, sizeof(*fiemap_s));
+
+out_free:
+ kfree(fiemap_s);
+ return err;
+}
+
Index: linux-2.6.25-rc1/fs/ext4/file.c
===================================================================
--- linux-2.6.25-rc1.orig/fs/ext4/file.c
+++ linux-2.6.25-rc1/fs/ext4/file.c
@@ -140,6 +140,9 @@ static int ext4_file_mmap(struct file *f
return 0;
}
+/* XXX ERS should this go into this file? */
+extern int ext4_fiemap(struct inode *inode, unsigned long arg);
+
const struct file_operations ext4_file_operations = {
.llseek = generic_file_llseek,
.read = do_sync_read,
@@ -169,5 +172,6 @@ const struct inode_operations ext4_file_
#endif
.permission = ext4_permission,
.fallocate = ext4_fallocate,
+ .fiemap = ext4_fiemap,
};
Index: linux-2.6.25-rc1/include/linux/ext4_fs.h
===================================================================
--- linux-2.6.25-rc1.orig/include/linux/ext4_fs.h
+++ linux-2.6.25-rc1/include/linux/ext4_fs.h
@@ -317,6 +317,8 @@ struct ext4_new_group_data {
#define EXT4_IOC32_GETVERSION_OLD FS_IOC32_GETVERSION
#define EXT4_IOC32_SETVERSION_OLD FS_IOC32_SETVERSION
+#define EXT4_FIEMAP_FLAG_INCOMPAT_UNSUPP (FIEMAP_FLAG_INCOMPAT & \
+ ~(FIEMAP_FLAG_LUN_OFFSET))
/*
* Mount options
Index: linux-2.6.25-rc1/include/linux/ext4_fs_extents.h
===================================================================
--- linux-2.6.25-rc1.orig/include/linux/ext4_fs_extents.h
+++ linux-2.6.25-rc1/include/linux/ext4_fs_extents.h
@@ -132,7 +132,7 @@ struct ext4_ext_path {
*/
typedef int (*ext_prepare_callback)(struct inode *, struct ext4_ext_path *,
struct ext4_ext_cache *,
- void *);
+ struct ext4_extent *, void *);
#define EXT_CONTINUE 0
#define EXT_BREAK 1
--
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