This patch implements sys_fallocate() and adds support on i386, x86_64
and powerpc platforms.
Changelog:
-
Following changes were made to the previous version:
1) Added description before sys_fallocate() definition.
2) Return EINVAL for len=0 (With new draft that Ulrich pointed to,
posix_fallocate should return EINVAL for len = 0.
3) Return EOPNOTSUPP if mode is not one of FA_ALLOCATE or FA_DEALLOCATE
4) Do not return ENODEV for dirs (let individual file systems decide if
they want to support preallocation to directories or not.
5) Check for wrap through zero.
6) Update c/mtime if fallocate() succeeds.
7) Added mode descriptions in fs.h
8) Added variable names to function definition (fallocate inode op)
Here is the new patch:
Signed-off-by: Amit Arora [EMAIL PROTECTED]
---
arch/i386/kernel/syscall_table.S |1
arch/powerpc/kernel/sys_ppc32.c |7 +++
arch/x86_64/kernel/functionlist |1
fs/open.c| 89 +++
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 | 13 +
include/linux/syscalls.h |1
10 files changed, 120 insertions(+), 3 deletions(-)
Index: linux-2.6.21/arch/i386/kernel/syscall_table.S
===
--- linux-2.6.21.orig/arch/i386/kernel/syscall_table.S
+++ linux-2.6.21/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-2.6.21/arch/x86_64/kernel/functionlist
===
--- linux-2.6.21.orig/arch/x86_64/kernel/functionlist
+++ linux-2.6.21/arch/x86_64/kernel/functionlist
@@ -931,6 +931,7 @@
*(.text.sys_getitimer)
*(.text.sys_getgroups)
*(.text.sys_ftruncate)
+*(.text.sys_fallocate)
*(.text.sysfs_lookup)
*(.text.sys_exit_group)
*(.text.stub_fork)
Index: linux-2.6.21/fs/open.c
===
--- linux-2.6.21.orig/fs/open.c
+++ linux-2.6.21/fs/open.c
@@ -351,6 +351,95 @@ asmlinkage long sys_ftruncate64(unsigned
#endif
/*
+ * sys_fallocate - preallocate blocks or free preallocated blocks
+ * @fd: the file descriptor
+ * @mode: mode specifies if fallocate should preallocate blocks OR free
+ * (unallocate) preallocated blocks. Currently only FA_ALLOCATE and
+ * FA_DEALLOCATE modes are supported.
+ * @offset: The offset within file, from where (un)allocation is being
+ * requested. It should not have a negative value.
+ * @len: The amount (in bytes) of space to be (un)allocated, from the offset.
+ *
+ * This system call, depending on the mode, preallocates or unallocates blocks
+ * for a file. The range of blocks depends on the value of offset and len
+ * arguments provided by the user/application. For FA_ALLOCATE mode, if this
+ * system call succeeds, subsequent writes to the file in the given range
+ * (specified by offset len) should not fail - even if the file system
+ * later becomes full. Hence the preallocation done is persistent (valid
+ * even after reopen of the file and remount/reboot).
+ *
+ * Note: Incase the file system does not support preallocation,
+ * posix_fallocate() should fall back to the library implementation (i.e.
+ * allocating zero-filled new blocks to the file).
+ *
+ * Return Values
+ * 0 : On SUCCESS a value of zero is returned.
+ * error : On Failure, an error code will be returned.
+ * An error code of -ENOSYS or -EOPNOTSUPP should make posix_fallocate()
+ * fall back on library implementation of fallocate.
+ *
+ * TBD Generic fallocate to be added for file systems that do not
+ * support fallocate it.
+ */
+asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
+{
+ struct file *file;
+ struct inode *inode;
+ long ret = -EINVAL;
+
+ if (offset 0 || len = 0)
+ goto out;
+
+ /* Return error if mode is not supported */
+ ret = -EOPNOTSUPP;
+ if (mode != FA_ALLOCATE mode !=FA_DEALLOCATE)
+ 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;
+ /*
+* Let individual file system decide if it supports preallocation
+* for directories or not.
+*/
+ if (!S_ISREG(inode-i_mode) !S_ISDIR(inode-i_mode))
+ goto out_fput;
+
+ ret = -EFBIG;
+ /* Check for wrap through zero too */
+ if (((offset +
