fs: add ksys_lseek() helper; remove in-kernel calls to sys_lseek()
Using this helper allows us to avoid the in-kernel calls to the sys_lseek() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_lseek(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
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@ -301,7 +301,7 @@ loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
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}
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EXPORT_SYMBOL(vfs_llseek);
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SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
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off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence)
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{
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off_t retval;
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struct fd f = fdget_pos(fd);
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@ -319,10 +319,15 @@ SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
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return retval;
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}
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SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
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{
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return ksys_lseek(fd, offset, whence);
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}
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#ifdef CONFIG_COMPAT
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COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence)
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{
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return sys_lseek(fd, offset, whence);
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return ksys_lseek(fd, offset, whence);
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}
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#endif
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@ -958,6 +958,7 @@ int ksys_fchown(unsigned int fd, uid_t user, gid_t group);
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int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
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unsigned int count);
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int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg);
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off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence);
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/*
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* The following kernel syscall equivalents are just wrappers to fs-internal
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@ -90,7 +90,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
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/*
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* Read block 0 to test for compressed kernel
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*/
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sys_lseek(fd, start_block * BLOCK_SIZE, 0);
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ksys_lseek(fd, start_block * BLOCK_SIZE, 0);
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sys_read(fd, buf, size);
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*decompressor = decompress_method(buf, size, &compress_name);
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@ -136,7 +136,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
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/*
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* Read 512 bytes further to check if cramfs is padded
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*/
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sys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
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ksys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
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sys_read(fd, buf, size);
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if (cramfsb->magic == CRAMFS_MAGIC) {
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@ -150,7 +150,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
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/*
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* Read block 1 to test for minix and ext2 superblock
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*/
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sys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
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ksys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
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sys_read(fd, buf, size);
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/* Try minix */
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@ -178,7 +178,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
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start_block);
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done:
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sys_lseek(fd, start_block * BLOCK_SIZE, 0);
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ksys_lseek(fd, start_block * BLOCK_SIZE, 0);
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kfree(buf);
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return nblocks;
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}
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