![Josef Bacik](/assets/img/avatar_default.png)
Any block based fs (this patch includes ext3) just has to declare its own fiemap() function and then call this generic function with its own get_block_t. This works well for block based filesystems that will map multiple contiguous blocks at one time, but will work for filesystems that only map one block at a time, you will just end up with an "extent" for each block. One gotcha is this will not play nicely where there is hole+data after the EOF. This function will assume its hit the end of the data as soon as it hits a hole after the EOF, so if there is any data past that it will not pick that up. AFAIK no block based fs does this anyway, but its in the comments of the function anyway just in case. Signed-off-by: Josef Bacik <jbacik@redhat.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: linux-fsdevel@vger.kernel.org
487 lines
12 KiB
C
487 lines
12 KiB
C
/*
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* linux/fs/ioctl.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/syscalls.h>
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#include <linux/mm.h>
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#include <linux/smp_lock.h>
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#include <linux/capability.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/security.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/writeback.h>
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#include <linux/buffer_head.h>
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#include <asm/ioctls.h>
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/* So that the fiemap access checks can't overflow on 32 bit machines. */
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#define FIEMAP_MAX_EXTENTS (UINT_MAX / sizeof(struct fiemap_extent))
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/**
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* vfs_ioctl - call filesystem specific ioctl methods
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* @filp: open file to invoke ioctl method on
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* @cmd: ioctl command to execute
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* @arg: command-specific argument for ioctl
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*
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* Invokes filesystem specific ->unlocked_ioctl, if one exists; otherwise
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* invokes filesystem specific ->ioctl method. If neither method exists,
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* returns -ENOTTY.
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*
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* Returns 0 on success, -errno on error.
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*/
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static long vfs_ioctl(struct file *filp, unsigned int cmd,
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unsigned long arg)
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{
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int error = -ENOTTY;
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if (!filp->f_op)
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goto out;
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if (filp->f_op->unlocked_ioctl) {
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error = filp->f_op->unlocked_ioctl(filp, cmd, arg);
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if (error == -ENOIOCTLCMD)
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error = -EINVAL;
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goto out;
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} else if (filp->f_op->ioctl) {
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lock_kernel();
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error = filp->f_op->ioctl(filp->f_path.dentry->d_inode,
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filp, cmd, arg);
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unlock_kernel();
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}
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out:
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return error;
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}
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static int ioctl_fibmap(struct file *filp, int __user *p)
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{
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struct address_space *mapping = filp->f_mapping;
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int res, block;
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/* do we support this mess? */
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if (!mapping->a_ops->bmap)
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return -EINVAL;
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if (!capable(CAP_SYS_RAWIO))
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return -EPERM;
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res = get_user(block, p);
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if (res)
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return res;
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lock_kernel();
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res = mapping->a_ops->bmap(mapping, block);
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unlock_kernel();
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return put_user(res, p);
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}
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/**
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* fiemap_fill_next_extent - Fiemap helper function
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* @fieinfo: Fiemap context passed into ->fiemap
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* @logical: Extent logical start offset, in bytes
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* @phys: Extent physical start offset, in bytes
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* @len: Extent length, in bytes
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* @flags: FIEMAP_EXTENT flags that describe this extent
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*
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* Called from file system ->fiemap callback. Will populate extent
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* info as passed in via arguments and copy to user memory. On
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* success, extent count on fieinfo is incremented.
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*
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* Returns 0 on success, -errno on error, 1 if this was the last
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* extent that will fit in user array.
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*/
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#define SET_UNKNOWN_FLAGS (FIEMAP_EXTENT_DELALLOC)
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#define SET_NO_UNMOUNTED_IO_FLAGS (FIEMAP_EXTENT_DATA_ENCRYPTED)
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#define SET_NOT_ALIGNED_FLAGS (FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
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int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
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u64 phys, u64 len, u32 flags)
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{
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struct fiemap_extent extent;
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struct fiemap_extent *dest = fieinfo->fi_extents_start;
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/* only count the extents */
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if (fieinfo->fi_extents_max == 0) {
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fieinfo->fi_extents_mapped++;
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return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
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}
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if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max)
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return 1;
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if (flags & SET_UNKNOWN_FLAGS)
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flags |= FIEMAP_EXTENT_UNKNOWN;
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if (flags & SET_NO_UNMOUNTED_IO_FLAGS)
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flags |= FIEMAP_EXTENT_ENCODED;
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if (flags & SET_NOT_ALIGNED_FLAGS)
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flags |= FIEMAP_EXTENT_NOT_ALIGNED;
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memset(&extent, 0, sizeof(extent));
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extent.fe_logical = logical;
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extent.fe_physical = phys;
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extent.fe_length = len;
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extent.fe_flags = flags;
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dest += fieinfo->fi_extents_mapped;
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if (copy_to_user(dest, &extent, sizeof(extent)))
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return -EFAULT;
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fieinfo->fi_extents_mapped++;
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if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
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return 1;
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return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
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}
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EXPORT_SYMBOL(fiemap_fill_next_extent);
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/**
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* fiemap_check_flags - check validity of requested flags for fiemap
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* @fieinfo: Fiemap context passed into ->fiemap
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* @fs_flags: Set of fiemap flags that the file system understands
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*
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* Called from file system ->fiemap callback. This will compute the
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* intersection of valid fiemap flags and those that the fs supports. That
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* value is then compared against the user supplied flags. In case of bad user
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* flags, the invalid values will be written into the fieinfo structure, and
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* -EBADR is returned, which tells ioctl_fiemap() to return those values to
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* userspace. For this reason, a return code of -EBADR should be preserved.
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*
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* Returns 0 on success, -EBADR on bad flags.
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*/
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int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
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{
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u32 incompat_flags;
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incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
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if (incompat_flags) {
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fieinfo->fi_flags = incompat_flags;
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return -EBADR;
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}
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return 0;
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}
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EXPORT_SYMBOL(fiemap_check_flags);
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static int fiemap_check_ranges(struct super_block *sb,
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u64 start, u64 len, u64 *new_len)
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{
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*new_len = len;
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if (len == 0)
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return -EINVAL;
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if (start > sb->s_maxbytes)
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return -EFBIG;
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/*
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* Shrink request scope to what the fs can actually handle.
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*/
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if ((len > sb->s_maxbytes) ||
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(sb->s_maxbytes - len) < start)
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*new_len = sb->s_maxbytes - start;
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return 0;
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}
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static int ioctl_fiemap(struct file *filp, unsigned long arg)
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{
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struct fiemap fiemap;
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struct fiemap_extent_info fieinfo = { 0, };
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struct inode *inode = filp->f_path.dentry->d_inode;
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struct super_block *sb = inode->i_sb;
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u64 len;
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int error;
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if (!inode->i_op->fiemap)
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return -EOPNOTSUPP;
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if (copy_from_user(&fiemap, (struct fiemap __user *)arg,
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sizeof(struct fiemap)))
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return -EFAULT;
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if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
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return -EINVAL;
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error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
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&len);
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if (error)
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return error;
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fieinfo.fi_flags = fiemap.fm_flags;
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fieinfo.fi_extents_max = fiemap.fm_extent_count;
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fieinfo.fi_extents_start = (struct fiemap_extent *)(arg + sizeof(fiemap));
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if (fiemap.fm_extent_count != 0 &&
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!access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
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fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
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return -EFAULT;
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if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
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filemap_write_and_wait(inode->i_mapping);
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error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
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fiemap.fm_flags = fieinfo.fi_flags;
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fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
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if (copy_to_user((char *)arg, &fiemap, sizeof(fiemap)))
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error = -EFAULT;
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return error;
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}
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#define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
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#define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
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/*
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* @inode - the inode to map
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* @arg - the pointer to userspace where we copy everything to
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* @get_block - the fs's get_block function
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*
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* This does FIEMAP for block based inodes. Basically it will just loop
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* through get_block until we hit the number of extents we want to map, or we
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* go past the end of the file and hit a hole.
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*
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* If it is possible to have data blocks beyond a hole past @inode->i_size, then
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* please do not use this function, it will stop at the first unmapped block
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* beyond i_size
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*/
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int generic_block_fiemap(struct inode *inode,
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struct fiemap_extent_info *fieinfo, u64 start,
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u64 len, get_block_t *get_block)
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{
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struct buffer_head tmp;
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unsigned int start_blk;
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long long length = 0, map_len = 0;
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u64 logical = 0, phys = 0, size = 0;
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u32 flags = FIEMAP_EXTENT_MERGED;
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int ret = 0;
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if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
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return ret;
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start_blk = logical_to_blk(inode, start);
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/* guard against change */
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mutex_lock(&inode->i_mutex);
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length = (long long)min_t(u64, len, i_size_read(inode));
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map_len = length;
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do {
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/*
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* we set b_size to the total size we want so it will map as
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* many contiguous blocks as possible at once
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*/
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memset(&tmp, 0, sizeof(struct buffer_head));
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tmp.b_size = map_len;
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ret = get_block(inode, start_blk, &tmp, 0);
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if (ret)
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break;
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/* HOLE */
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if (!buffer_mapped(&tmp)) {
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/*
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* first hole after going past the EOF, this is our
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* last extent
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*/
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if (length <= 0) {
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flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
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ret = fiemap_fill_next_extent(fieinfo, logical,
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phys, size,
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flags);
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break;
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}
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length -= blk_to_logical(inode, 1);
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/* if we have holes up to/past EOF then we're done */
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if (length <= 0)
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break;
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start_blk++;
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} else {
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if (length <= 0 && size) {
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ret = fiemap_fill_next_extent(fieinfo, logical,
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phys, size,
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flags);
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if (ret)
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break;
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}
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logical = blk_to_logical(inode, start_blk);
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phys = blk_to_logical(inode, tmp.b_blocknr);
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size = tmp.b_size;
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flags = FIEMAP_EXTENT_MERGED;
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length -= tmp.b_size;
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start_blk += logical_to_blk(inode, size);
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/*
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* if we are past the EOF we need to loop again to see
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* if there is a hole so we can mark this extent as the
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* last one, and if not keep mapping things until we
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* find a hole, or we run out of slots in the extent
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* array
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*/
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if (length <= 0)
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continue;
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ret = fiemap_fill_next_extent(fieinfo, logical, phys,
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size, flags);
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if (ret)
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break;
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}
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cond_resched();
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} while (1);
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mutex_unlock(&inode->i_mutex);
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/* if ret is 1 then we just hit the end of the extent array */
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if (ret == 1)
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ret = 0;
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return ret;
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}
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EXPORT_SYMBOL(generic_block_fiemap);
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static int file_ioctl(struct file *filp, unsigned int cmd,
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unsigned long arg)
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{
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struct inode *inode = filp->f_path.dentry->d_inode;
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int __user *p = (int __user *)arg;
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switch (cmd) {
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case FIBMAP:
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return ioctl_fibmap(filp, p);
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case FS_IOC_FIEMAP:
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return ioctl_fiemap(filp, arg);
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case FIGETBSZ:
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return put_user(inode->i_sb->s_blocksize, p);
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case FIONREAD:
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return put_user(i_size_read(inode) - filp->f_pos, p);
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}
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return vfs_ioctl(filp, cmd, arg);
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}
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static int ioctl_fionbio(struct file *filp, int __user *argp)
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{
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unsigned int flag;
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int on, error;
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error = get_user(on, argp);
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if (error)
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return error;
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flag = O_NONBLOCK;
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#ifdef __sparc__
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/* SunOS compatibility item. */
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if (O_NONBLOCK != O_NDELAY)
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flag |= O_NDELAY;
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#endif
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if (on)
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filp->f_flags |= flag;
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else
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filp->f_flags &= ~flag;
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return error;
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}
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static int ioctl_fioasync(unsigned int fd, struct file *filp,
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int __user *argp)
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{
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unsigned int flag;
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int on, error;
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error = get_user(on, argp);
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if (error)
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return error;
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flag = on ? FASYNC : 0;
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/* Did FASYNC state change ? */
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if ((flag ^ filp->f_flags) & FASYNC) {
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if (filp->f_op && filp->f_op->fasync) {
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lock_kernel();
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error = filp->f_op->fasync(fd, filp, on);
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unlock_kernel();
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} else
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error = -ENOTTY;
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}
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if (error)
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return error;
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if (on)
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filp->f_flags |= FASYNC;
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else
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filp->f_flags &= ~FASYNC;
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return error;
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}
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/*
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* When you add any new common ioctls to the switches above and below
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* please update compat_sys_ioctl() too.
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*
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* do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
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* It's just a simple helper for sys_ioctl and compat_sys_ioctl.
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*/
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int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
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unsigned long arg)
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{
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int error = 0;
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int __user *argp = (int __user *)arg;
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switch (cmd) {
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case FIOCLEX:
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set_close_on_exec(fd, 1);
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break;
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case FIONCLEX:
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set_close_on_exec(fd, 0);
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break;
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case FIONBIO:
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error = ioctl_fionbio(filp, argp);
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break;
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case FIOASYNC:
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error = ioctl_fioasync(fd, filp, argp);
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break;
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case FIOQSIZE:
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if (S_ISDIR(filp->f_path.dentry->d_inode->i_mode) ||
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S_ISREG(filp->f_path.dentry->d_inode->i_mode) ||
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S_ISLNK(filp->f_path.dentry->d_inode->i_mode)) {
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loff_t res =
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inode_get_bytes(filp->f_path.dentry->d_inode);
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error = copy_to_user((loff_t __user *)arg, &res,
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sizeof(res)) ? -EFAULT : 0;
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} else
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error = -ENOTTY;
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break;
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default:
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if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
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error = file_ioctl(filp, cmd, arg);
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else
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error = vfs_ioctl(filp, cmd, arg);
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break;
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}
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return error;
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}
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asmlinkage long sys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg)
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{
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struct file *filp;
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int error = -EBADF;
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int fput_needed;
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filp = fget_light(fd, &fput_needed);
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if (!filp)
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goto out;
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error = security_file_ioctl(filp, cmd, arg);
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if (error)
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goto out_fput;
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error = do_vfs_ioctl(filp, fd, cmd, arg);
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out_fput:
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fput_light(filp, fput_needed);
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out:
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return error;
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}
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