On 4/18/2016 4:47 PM, Jan Kara wrote:
On Thu 14-04-16 10:48:30, Toshi Kani wrote:
+
+/**
+ * dax_get_unmapped_area - handle get_unmapped_area for a DAX file
+ * @filp: The file being mmap'd, if not NULL
+ * @addr: The mmap address. If NULL, the kernel assigns the address
+ * @len: The mmap size in bytes
+ * @pgoff: The page offset in the file where the mapping starts from.
+ * @flags: The mmap flags
+ *
+ * This function can be called by a filesystem for get_unmapped_area().
+ * When a target file is a DAX file, it aligns the mmap address at the
+ * beginning of the file by the pmd size.
+ */
+unsigned long dax_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ unsigned long off, off_end, off_pmd, len_pmd, addr_pmd;
I think we need to use 'loff_t' for the offsets for things to work on
32-bits.
Agreed. Will change to loff_t.
+ if (!IS_ENABLED(CONFIG_FS_DAX_PMD) ||
+ !filp || addr || !IS_DAX(filp->f_mapping->host))
+ goto out;
+
+ off = pgoff << PAGE_SHIFT;
And here we need to type to loff_t before the shift...
Right.
+ off_end = off + len;
+ off_pmd = round_up(off, PMD_SIZE); /* pmd-aligned offset */
+
+ if ((off_end <= off_pmd) || ((off_end - off_pmd) < PMD_SIZE))
None of these parenthesis is actually needed (and IMHO they make the code
less readable, not more).
OK. Will remove the parenthesis.
+ goto out;
+
+ len_pmd = len + PMD_SIZE;
+ if ((off + len_pmd) < off)
+ goto out;
+
+ addr_pmd = current->mm->get_unmapped_area(filp, addr, len_pmd,
+ pgoff, flags);
+ if (!IS_ERR_VALUE(addr_pmd)) {
+ addr_pmd += (off - addr_pmd) & (PMD_SIZE - 1);
+ return addr_pmd;
Otherwise the patch looks good to me.
Great. Thanks Jan!
-Toshi
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