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Re: [RFC][PATCH] sys_fallocate() system call

To: Matthew Wilcox <matthew@xxxxxx>
Subject: Re: [RFC][PATCH] sys_fallocate() system call
From: "Amit K. Arora" <aarora@xxxxxxxxxxxxxxxxxx>
Date: Wed, 21 Mar 2007 17:34:25 +0530
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, suparna@xxxxxxxxxx, cmm@xxxxxxxxxx, alex@xxxxxxxxxxxxx, suzuki@xxxxxxxxxx
In-reply-to: <20070317111036.GC29931@xxxxxxxxxxxxxxxx>
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On Sat, Mar 17, 2007 at 05:10:37AM -0600, Matthew Wilcox wrote:
> How about:
> 
> asmlinkage long sys_fallocate(int fd, int mode, u32 off_low, u32 off_high,
>                               u32 len_low, u32 len_high);
> 
> That way we all suffer equally ...

As suggested by you and Russel, I have made this change to the patch.
Here is how it looks like now. Please let me know if anyone has concerns
about passing arguments this way (breaking each "loff_t" into two "u32"s).

Signed-off-by: Amit K Arora <aarora@xxxxxxxxxx>
---
 arch/i386/kernel/syscall_table.S |    1 
 arch/x86_64/kernel/functionlist  |    1 
 fs/open.c                        |   46 +++++++++++++++++++++++++++++++++++++++
 include/asm-i386/unistd.h        |    3 +-
 include/asm-powerpc/systbl.h     |    1 
 include/asm-powerpc/unistd.h     |    3 +-
 include/asm-x86_64/unistd.h      |    4 ++-
 include/linux/fs.h               |    7 +++++
 include/linux/syscalls.h         |    2 +
 9 files changed, 65 insertions(+), 3 deletions(-)

Index: linux-2.6.20.1/arch/i386/kernel/syscall_table.S
===================================================================
--- linux-2.6.20.1.orig/arch/i386/kernel/syscall_table.S
+++ linux-2.6.20.1/arch/i386/kernel/syscall_table.S
@@ -319,3 +319,4 @@ ENTRY(sys_call_table)
        .long sys_move_pages
        .long sys_getcpu
        .long sys_epoll_pwait
+       .long sys_fallocate             /* 320 */
Index: linux-2.6.20.1/fs/open.c
===================================================================
--- linux-2.6.20.1.orig/fs/open.c
+++ linux-2.6.20.1/fs/open.c
@@ -350,6 +350,52 @@ asmlinkage long sys_ftruncate64(unsigned
 }
 #endif
 
+asmlinkage long sys_fallocate(int fd, int mode, u32 off_low, u32 off_high,
+                               u32 len_low, u32 len_high)
+{
+       struct file *file;
+       struct inode *inode;
+       loff_t offset, len;
+       long ret = -EINVAL;
+
+       offset = (off_high << 32) + off_low;
+       len = (len_high << 32) + len_low;
+
+       if (len == 0 || offset < 0)
+               goto out;
+
+       ret = -EBADF;
+       file = fget(fd);
+       if (!file)
+               goto out;
+       if (!(file->f_mode & FMODE_WRITE))
+               goto out_fput;
+
+       inode = file->f_path.dentry->d_inode;
+
+       ret = -ESPIPE;
+       if (S_ISFIFO(inode->i_mode))
+               goto out_fput;
+
+       ret = -ENODEV;
+       if (!S_ISREG(inode->i_mode))
+               goto out_fput;
+
+       ret = -EFBIG;
+       if (offset + len > inode->i_sb->s_maxbytes)
+               goto out_fput;
+
+       if (inode->i_op && inode->i_op->fallocate)
+               ret = inode->i_op->fallocate(inode, mode, offset, len);
+       else
+               ret = -ENOSYS;
+out_fput:
+       fput(file);
+out:
+       return ret;
+}
+EXPORT_SYMBOL(sys_fallocate);
+
 /*
  * access() needs to use the real uid/gid, not the effective uid/gid.
  * We do this by temporarily clearing all FS-related capabilities and
Index: linux-2.6.20.1/include/asm-i386/unistd.h
===================================================================
--- linux-2.6.20.1.orig/include/asm-i386/unistd.h
+++ linux-2.6.20.1/include/asm-i386/unistd.h
@@ -325,10 +325,11 @@
 #define __NR_move_pages                317
 #define __NR_getcpu            318
 #define __NR_epoll_pwait       319
+#define __NR_fallocate         320
 
 #ifdef __KERNEL__
 
-#define NR_syscalls 320
+#define NR_syscalls 321
 
 #define __ARCH_WANT_IPC_PARSE_VERSION
 #define __ARCH_WANT_OLD_READDIR
Index: linux-2.6.20.1/include/linux/fs.h
===================================================================
--- linux-2.6.20.1.orig/include/linux/fs.h
+++ linux-2.6.20.1/include/linux/fs.h
@@ -263,6 +263,12 @@ extern int dir_notify_enable;
 #define SYNC_FILE_RANGE_WRITE          2
 #define SYNC_FILE_RANGE_WAIT_AFTER     4
 
+/*
+ * fallocate() modes
+ */
+#define FA_ALLOCATE    0x1
+#define FA_DEALLOCATE  0x2
+
 #ifdef __KERNEL__
 
 #include <linux/linkage.h>
@@ -1124,6 +1130,7 @@ struct inode_operations {
        ssize_t (*listxattr) (struct dentry *, char *, size_t);
        int (*removexattr) (struct dentry *, const char *);
        void (*truncate_range)(struct inode *, loff_t, loff_t);
+       int (*fallocate)(struct inode *, int, loff_t, loff_t);
 };
 
 struct seq_file;
Index: linux-2.6.20.1/include/linux/syscalls.h
===================================================================
--- linux-2.6.20.1.orig/include/linux/syscalls.h
+++ linux-2.6.20.1/include/linux/syscalls.h
@@ -602,6 +602,8 @@ asmlinkage long sys_get_robust_list(int 
 asmlinkage long sys_set_robust_list(struct robust_list_head __user *head,
                                    size_t len);
 asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct 
getcpu_cache __user *cache);
+asmlinkage long sys_fallocate(int fd, int mode, u32 off_low, u32 off_high,
+                               u32 len_low, u32 len_high);
 
 int kernel_execve(const char *filename, char *const argv[], char *const 
envp[]);
 
Index: linux-2.6.20.1/include/asm-x86_64/unistd.h
===================================================================
--- linux-2.6.20.1.orig/include/asm-x86_64/unistd.h
+++ linux-2.6.20.1/include/asm-x86_64/unistd.h
@@ -619,8 +619,10 @@ __SYSCALL(__NR_sync_file_range, sys_sync
 __SYSCALL(__NR_vmsplice, sys_vmsplice)
 #define __NR_move_pages                279
 __SYSCALL(__NR_move_pages, sys_move_pages)
+#define __NR_fallocate         280
+__SYSCALL(__NR_fallocate, sys_fallocate)
 
-#define __NR_syscall_max __NR_move_pages
+#define __NR_syscall_max __NR_fallocate
 
 #ifndef __NO_STUBS
 #define __ARCH_WANT_OLD_READDIR
Index: linux-2.6.20.1/include/asm-powerpc/unistd.h
===================================================================
--- linux-2.6.20.1.orig/include/asm-powerpc/unistd.h
+++ linux-2.6.20.1/include/asm-powerpc/unistd.h
@@ -324,10 +324,11 @@
 #define __NR_get_robust_list   299
 #define __NR_set_robust_list   300
 #define __NR_move_pages                301
+#define __NR_fallocate         302
 
 #ifdef __KERNEL__
 
-#define __NR_syscalls          302
+#define __NR_syscalls          303
 
 #define __NR__exit __NR_exit
 #define NR_syscalls    __NR_syscalls
Index: linux-2.6.20.1/arch/x86_64/kernel/functionlist
===================================================================
--- linux-2.6.20.1.orig/arch/x86_64/kernel/functionlist
+++ linux-2.6.20.1/arch/x86_64/kernel/functionlist
@@ -932,6 +932,7 @@
 *(.text.sys_getitimer)
 *(.text.sys_getgroups)
 *(.text.sys_ftruncate)
+*(.text.sys_fallocate)
 *(.text.sysfs_lookup)
 *(.text.sys_exit_group)
 *(.text.stub_fork)
Index: linux-2.6.20.1/include/asm-powerpc/systbl.h
===================================================================
--- linux-2.6.20.1.orig/include/asm-powerpc/systbl.h
+++ linux-2.6.20.1/include/asm-powerpc/systbl.h
@@ -305,3 +305,4 @@ SYSCALL_SPU(faccessat)
 COMPAT_SYS_SPU(get_robust_list)
 COMPAT_SYS_SPU(set_robust_list)
 COMPAT_SYS(move_pages)
+SYSCALL(fallocate)
--
Regards,
Amit Arora


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