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Btrfs: fiemap support

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Now that bmap support is gone, this is the only way to get extent
mappings for userland.  These are still not valid for IO, but they
can tell us if a file has holes or how much fragmentation there is.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
This commit is contained in:
Yehuda Sadeh
2009-01-21 14:39:14 -05:00
committed by Chris Mason
parent 35054394c4
commit 1506fcc818
3 changed files with 101 additions and 0 deletions
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92
fs/btrfs/extent_io.c
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@@ -2854,6 +2854,98 @@ out:
return sector;
}
int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len, get_extent_t *get_extent)
{
int ret;
u64 off = start;
u64 max = start + len;
u32 flags = 0;
u64 disko = 0;
struct extent_map *em = NULL;
int end = 0;
u64 em_start = 0, em_len = 0;
unsigned long emflags;
ret = 0;
if (len == 0)
return -EINVAL;
lock_extent(&BTRFS_I(inode)->io_tree, start, start + len,
GFP_NOFS);
em = get_extent(inode, NULL, 0, off, max - off, 0);
if (!em)
goto out;
if (IS_ERR(em)) {
ret = PTR_ERR(em);
goto out;
}
while (!end) {
off = em->start + em->len;
if (off >= max)
end = 1;
em_start = em->start;
em_len = em->len;
disko = 0;
flags = 0;
switch (em->block_start) {
case EXTENT_MAP_LAST_BYTE:
end = 1;
flags |= FIEMAP_EXTENT_LAST;
break;
case EXTENT_MAP_HOLE:
flags |= FIEMAP_EXTENT_UNWRITTEN;
break;
case EXTENT_MAP_INLINE:
flags |= (FIEMAP_EXTENT_DATA_INLINE |
FIEMAP_EXTENT_NOT_ALIGNED);
break;
case EXTENT_MAP_DELALLOC:
flags |= (FIEMAP_EXTENT_DELALLOC |
FIEMAP_EXTENT_UNKNOWN);
break;
default:
disko = em->block_start;
break;
}
if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
flags |= FIEMAP_EXTENT_ENCODED;
emflags = em->flags;
free_extent_map(em);
em = NULL;
if (!end) {
em = get_extent(inode, NULL, 0, off, max - off, 0);
if (!em)
goto out;
if (IS_ERR(em)) {
ret = PTR_ERR(em);
goto out;
}
emflags = em->flags;
}
if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) {
flags |= FIEMAP_EXTENT_LAST;
end = 1;
}
ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
em_len, flags);
if (ret)
goto out_free;
}
out_free:
free_extent_map(em);
out:
unlock_extent(&BTRFS_I(inode)->io_tree, start, start + len,
GFP_NOFS);
return ret;
}
static inline struct page *extent_buffer_page(struct extent_buffer *eb,
unsigned long i)
{