Cleanup generic block based fiemap

This cleans up a few of the complaints of __generic_block_fiemap.  I've
fixed all the typing stuff, used inline functions instead of macros,
gotten rid of a couple of variables, and made sure the size and block
requests are all block aligned.  It also fixes a problem where sometimes
FIEMAP_EXTENT_LAST wasn't being set properly.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 53 insertions, 39 deletions

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 6c751106c2e5..7faefb4da939 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -228,14 +228,23 @@ static int ioctl_fiemap(struct file *filp, unsigned long arg)
 
 #ifdef CONFIG_BLOCK
 
-#define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
-#define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
+static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
+{
+        return (offset >> inode->i_blkbits);
+}
+
+static inline loff_t blk_to_logical(struct inode *inode, sector_t blk)
+{
+        return (blk << inode->i_blkbits);
+}
 
 /**
  * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
- * @inode - the inode to map
- * @arg - the pointer to userspace where we copy everything to
- * @get_block - the fs's get_block function
+ * @inode: the inode to map
+ * @fieinfo: the fiemap info struct that will be passed back to userspace
+ * @start: where to start mapping in the inode
+ * @len: how much space to map
+ * @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
@@ -250,58 +259,63 @@ static int ioctl_fiemap(struct file *filp, unsigned long arg)
  */
 
 int __generic_block_fiemap(struct inode *inode,
-                           struct fiemap_extent_info *fieinfo, u64 start,
-                           u64 len, get_block_t *get_block)
+                           struct fiemap_extent_info *fieinfo, loff_t start,
+                           loff_t len, get_block_t *get_block)
 {
-        struct buffer_head tmp;
-        unsigned long long start_blk;
-        long long length = 0, map_len = 0;
+        struct buffer_head map_bh;
+        sector_t start_blk, last_blk;
+        loff_t isize = i_size_read(inode);
         u64 logical = 0, phys = 0, size = 0;
         u32 flags = FIEMAP_EXTENT_MERGED;
-        int ret = 0, past_eof = 0, whole_file = 0;
+        bool past_eof = false, whole_file = false;
+        int ret = 0;
 
-        if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
+        ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
+        if (ret)
                 return ret;
 
-        start_blk = logical_to_blk(inode, start);
-
-        length = (long long)min_t(u64, len, i_size_read(inode));
-        if (length < len)
-                whole_file = 1;
+        /*
+         * Either the i_mutex or other appropriate locking needs to be held
+         * since we expect isize to not change at all through the duration of
+         * this call.
+         */
+        if (len >= isize) {
+                whole_file = true;
+                len = isize;
+        }
 
-        map_len = length;
+        start_blk = logical_to_blk(inode, start);
+        last_blk = logical_to_blk(inode, start + len - 1);
 
         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;
+                memset(&map_bh, 0, sizeof(struct buffer_head));
+                map_bh.b_size = len;
 
-                ret = get_block(inode, start_blk, &tmp, 0);
+                ret = get_block(inode, start_blk, &map_bh, 0);
                 if (ret)
                         break;
 
                 /* HOLE */
-                if (!buffer_mapped(&tmp)) {
-                        length -= blk_to_logical(inode, 1);
+                if (!buffer_mapped(&map_bh)) {
                         start_blk++;
 
                         /*
-                         * we want to handle the case where there is an
+                         * We want to handle the case where there is an
                          * allocated block at the front of the file, and then
                          * nothing but holes up to the end of the file properly,
                          * to make sure that extent at the front gets properly
                          * marked with FIEMAP_EXTENT_LAST
                          */
                         if (!past_eof &&
-                            blk_to_logical(inode, start_blk) >=
-                            blk_to_logical(inode, 0)+i_size_read(inode))
+                            blk_to_logical(inode, start_blk) >= isize)
                                 past_eof = 1;
 
                         /*
-                         * first hole after going past the EOF, this is our
+                         * First hole after going past the EOF, this is our
                          * last extent
                          */
                         if (past_eof && size) {
@@ -309,15 +323,18 @@ int __generic_block_fiemap(struct inode *inode,
                                 ret = fiemap_fill_next_extent(fieinfo, logical,
                                                               phys, size,
                                                               flags);
-                                break;
+                        } else if (size) {
+                                ret = fiemap_fill_next_extent(fieinfo, logical,
+                                                              phys, size, flags);
+                                size = 0;
                         }
 
                         /* if we have holes up to/past EOF then we're done */
-                        if (length <= 0 || past_eof)
+                        if (start_blk > last_blk || past_eof || ret)
                                 break;
                 } else {
                         /*
-                         * we have gone over the length of what we wanted to
+                         * We have gone over the length of what we wanted to
                          * map, and it wasn't the entire file, so add the extent
                          * we got last time and exit.
                          *
@@ -331,7 +348,7 @@ int __generic_block_fiemap(struct inode *inode,
                          * are good to go, just add the extent to the fieinfo
                          * and break
                          */
-                        if (length <= 0 && !whole_file) {
+                        if (start_blk > last_blk && !whole_file) {
                                 ret = fiemap_fill_next_extent(fieinfo, logical,
                                                               phys, size,
                                                               flags);
@@ -351,11 +368,10 @@ int __generic_block_fiemap(struct inode *inode,
                         }
 
                         logical = blk_to_logical(inode, start_blk);
-                        phys = blk_to_logical(inode, tmp.b_blocknr);
-                        size = tmp.b_size;
+                        phys = blk_to_logical(inode, map_bh.b_blocknr);
+                        size = map_bh.b_size;
                         flags = FIEMAP_EXTENT_MERGED;
 
-                        length -= tmp.b_size;
                         start_blk += logical_to_blk(inode, size);
 
                         /*
@@ -363,15 +379,13 @@ int __generic_block_fiemap(struct inode *inode,
                          * soon as we find a hole that the last extent we found
                          * is marked with FIEMAP_EXTENT_LAST
                          */
-                        if (!past_eof &&
-                            logical+size >=
-                            blk_to_logical(inode, 0)+i_size_read(inode))
-                                past_eof = 1;
+                        if (!past_eof && logical + size >= isize)
+                                past_eof = true;
                 }
                 cond_resched();
         } while (1);
 
-        /* if ret is 1 then we just hit the end of the extent array */
+        /* If ret is 1 then we just hit the end of the extent array */
         if (ret == 1)
                 ret = 0;