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fs: Enable bmap() function to properly return errors

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By now, bmap() will either return the physical block number related to
the requested file offset or 0 in case of error or the requested offset
maps into a hole.
This patch makes the needed changes to enable bmap() to proper return
errors, using the return value as an error return, and now, a pointer
must be passed to bmap() to be filled with the mapped physical block.

It will change the behavior of bmap() on return:

- negative value in case of error
- zero on success or map fell into a hole

In case of a hole, the *block will be zero too

Since this is a prep patch, by now, the only error return is -EINVAL if
->bmap doesn't exist.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Carlos Maiolino
2020-01-09 14:30:41 +01:00
committed by Jaegeuk Kim
parent c8203f86b6
commit ae6e619e82
6 changed files with 69 additions and 35 deletions
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30
fs/inode.c
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@@ -1576,25 +1576,31 @@ void iput(struct inode *inode)
}
EXPORT_SYMBOL(iput);
#ifdef CONFIG_BLOCK
/**
* bmap - find a block number in a file
* @inode: inode of file
* @block: block to find
* @inode: inode owning the block number being requested
* @block: pointer containing the block to find
*
* Returns the block number on the device holding the inode that
* is the disk block number for the block of the file requested.
* That is, asked for block 4 of inode 1 the function will return the
* disk block relative to the disk start that holds that block of the
* file.
* Replaces the value in *block with the block number on the device holding
* corresponding to the requested block number in the file.
* That is, asked for block 4 of inode 1 the function will replace the
* 4 in *block, with disk block relative to the disk start that holds that
* block of the file.
*
* Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
* hole, returns 0 and *block is also set to 0.
*/
sector_t bmap(struct inode *inode, sector_t block)
int bmap(struct inode *inode, sector_t *block)
{
sector_t res = 0;
if (inode->i_mapping->a_ops->bmap)
res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
return res;
if (!inode->i_mapping->a_ops->bmap)
return -EINVAL;
*block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
return 0;
}
EXPORT_SYMBOL(bmap);
#endif
/*
* With relative atime, only update atime if the previous atime is