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>

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 6c751106c2e56c7bc318a0fa5f42f528fb8ac363..7faefb4da93915be59bfe6a8ab2a9b37014b9b52 100644 (file)
--- 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;
 

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 39d57bc6cc7173b0bb324ae069e10d4b18a9c30d..44f35aea2f1fe8ea178aaa9428d8826033ca034c 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2315,8 +2315,9 @@ extern int vfs_fstatat(int , char __user *, struct kstat *, int);
 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);
+                                 struct fiemap_extent_info *fieinfo,
+                                 loff_t start, loff_t len,
+                                 get_block_t *get_block);
 extern int generic_block_fiemap(struct inode *inode,
                                struct fiemap_extent_info *fieinfo, u64 start,
                                u64 len, get_block_t *get_block);