[PATCH 0/5][TAKE8] fallocate system call

[PATCH 0/5][TAKE8] fallocate system call

[Amit K. Arora]

This is the latest fallocate patchset and is based on 2.6.22.

* Following are the changes from TAKE7:
1) Updated the man page.
2) Merged "revalidate write permissions" patch with the main falloc patch.
3) Added linux/falloc.h and moved FALLOC_FL_KEEP_SIZE flag to it.
   Also removed the two modes (FALLOC_ALLOCATE and FALLOC_RESV_SPACE).
4) Removed comment above sys_fallocate definition.
5) Updated the testcase below to use FALLOC_FL_KEEP_SIZE flag instead
   of previous two modes.

* Following are the changes from TAKE6:
1) We now just have two modes (and no deallocation modes).
2) Updated the man page
3) Added a new patch submitted by David P. Quigley  (Patch 3/6).
4) Used EXT_INIT_MAX_LEN instead of 0x8000 in Patch 6/6.
4) Included below in the end is a small testcase to test fallocate.


* Following are the changes from TAKE5 to TAKE6:
1) Rebased to 2.6.22
2) Added compat wrapper for x86_64
3) Dropped s390 and ia64 patches, since the platform maintaners can
   add the support for fallocate once it is in mainline.
4) Added a change suggested by Andreas for better extent-to-group
   alignment in ext4 (Patch 6/6). Please refer following post:
http://www.mail-archive.com/linux-ext4@vger.kernel.org/msg02445.html
5) Renamed mode flags and values from "FA_" to "FALLOC_"
6) Added manpage (updated version of the one initially submitted by
   David Chinner).


Todos:
-----
1> Implementation on other architectures (other than i386, x86_64,
   and ppc64). s390(x) and ia64 patches are ready and will be pushed
   by platform maintaners when the fallocate is in mainline.
2> A generic file system operation to handle fallocate
   (generic_fallocate), for filesystems that do _not_ have the fallocate
   inode operation implemented.
3> Changes to glibc,
   a) to support fallocate() system call
   b) to make posix_fallocate() and posix_fallocate64() call fallocate()
4> Patch to e2fsprogs to recognize and display uninitialized extents.


Following patches follow:
Patch 1/5 : manpage for fallocate
Patch 2/5 : fallocate() implementation in i386, x86_64 and powerpc
Patch 3/5 : ext4: fallocate support in ext4
Patch 4/5 : ext4: write support for preallocated blocks
Patch 5/5 : ext4: change for better extent-to-group alignment

**
Attached below is a small testcase to test fallocate. The __NR_fallocate will
need to be changed depending on the system call number in the kernel (it may
get changed due to merge) and also depending on the architecture.

--
Regards,
Amit Arora



#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>

#include <linux/unistd.h>
#include <sys/vfs.h>
#include <sys/stat.h>

#define VERBOSE 0

#define __NR_fallocate                324

#define FALLOC_FL_KEEP_SIZE	0x01

int do_fallocate(int fd, int mode, loff_t offset, loff_t len)
{
  int ret;

  if (VERBOSE)
  	printf("Trying to preallocate blocks (offset=%llu, len=%llu)\n",
		offset, len);
  ret = syscall(__NR_fallocate, fd, mode, offset, len);

  if (ret <0) {
        printf("SYSCALL: received error %d, ret=%d\n", errno, ret);
        close(fd);
        return(1);
  }

  if (VERBOSE)
  	printf("fallocate system call succedded !  ret=%d\n", ret);

  return ret;
}

int test_fallocate(int fd, int mode, loff_t offset, loff_t len)
{
  int ret, blocks;
  struct stat statbuf1, statbuf2;

  fstat(fd, &statbuf1);

  ret = do_fallocate(fd, mode, offset, len);

  fstat(fd, &statbuf2);

  /* check file size after preallocation */
  if (!mode) {
  	if (!ret && statbuf1.st_size < (offset + len) &&
	    statbuf2.st_size != (offset + len)) {
		printf("Error: fallocate succeeded, but the file size did not "
			"change, where it should have!\n");
		ret = 1;
	}
  } else if (statbuf1.st_size != statbuf2.st_size) {
	printf("Error : File size changed, when it should not have!\n");
	ret = 1;
  }

  blocks = ((statbuf2.st_blocks - statbuf1.st_blocks) * 512)/ statbuf2.st_blksize;

  /* Print report */
  printf("# FALLOCATE TEST REPORT #\n");
  printf("\tNew blocks preallocated = %d.\n", blocks);
  printf("\tNumber of bytes preallocated = %d\n", blocks * statbuf2.st_blksize);
  printf("\tOld file size = %d, New file size %d.\n",
	  statbuf1.st_size, statbuf2.st_size);
  printf("\tOld num blocks = %d, New num blocks %d.\n",
	  (statbuf1.st_blocks * 512)/1024, (statbuf2.st_blocks * 512)/1024);

  return ret;
}


int do_write(int fd, loff_t offset, loff_t len)
{
  int ret;
  char *buf;

  buf = (char *)malloc(len);
  if (!buf) {
	printf("error: malloc failed.\n");
	return(-1);
  }

  if (VERBOSE)
  	printf("Trying to write to file (offset=%llu, len=%llu)\n", 
		offset, len);

  ret = lseek(fd, offset, SEEK_SET);
  if (ret != offset) {
     	printf("lseek() failed error=%d, ret=%d\n", errno, ret);
  	close(fd); 
       	return(-1);
  }

  ret = write(fd, buf, len);
  if (ret != len) {
       	 printf("write() failed error=%d, ret=%d\n", errno, ret);
  		close(fd); 
       		return(-1);
  }

  if (VERBOSE)
  	printf("Write succedded ! Written %llu bytes ret=%d\n", len, ret);

  return ret;
}


int test_write(int fd, loff_t offset, loff_t len)
{
  int ret;

  ret = do_write(fd, offset, len);
  printf("# WRITE TEST REPORT #\n");
  if (ret > 0) printf("\t written %d bytes.\n", ret);
  else printf("\t write operation failed!\n");

  if (ret > 0) return 0;
  else return 1;
}

void usage(char **argv)
{
  printf("\n%s <option> <filename-with-path> <offset> <length>\n", argv[0]);
  printf("option can be one of the following :\n");
  printf("\t-f\t: preallocate. This maps to default mode.\n");
  printf("\t-F\t: preallocate, but do not change the file size.\n");
  printf("\t\t    This maps to FALLOC_FL_KEEP_SIZE mode flag.\n");
  printf("\t-w\t: write some data to the range.\n");
  printf("\t-W\t: preallocate and write some data to the range.\n");
}

/*
 * Arguments:
 * argv[1] = option (-f/-F/-w/-W/-m)
 * argv[2] = fname	: the file name with path
 * argv[3] = offset	: in bytes
 * argv[4] = len	: in bytes
 */
int main(int argc, char **argv)
{
  int ret = 1, fd, mode;
  char *fname; 
  loff_t offset, len;

  if (argc!=5 || argv[1][0] != '-') {
	usage(argv);
	exit(1);
  }

  fname = argv[2];
  offset = (unsigned long long)atol(argv[3]);;
  len = (unsigned long long)atol(argv[4]);

  if (offset < 0 || len <= 0) {
        printf("%s: Invalid arguments.\n", argv[0]);
        exit(1);
  }

  fd = open(fname, O_CREAT|O_RDWR, 0666);
  if (fd < 0) {
        printf("Error opening file %s, error = %d.\n", fname, errno);
        exit(1);
  }

  /* -f */
  if (!strcmp(argv[1], "-f")) {
	mode = 0; /* default mode */
	ret = test_fallocate(fd, mode, offset, len);
  	if (ret) printf("test_fallocate: ERROR ! ret=%d\n", ret);
  /* -F */
  } else if (!strcmp(argv[1], "-F")) {
	mode = FALLOC_FL_KEEP_SIZE;
	ret = test_fallocate(fd, mode, offset, len);
  	if (ret) printf("test_fallocate: ERROR ! ret=%d\n", ret);
  /* -w */
  } else if (!strcmp(argv[1], "-w")) {
	ret = test_write(fd, offset, len);
  /* -W */
  } else if (!strcmp(argv[1], "-W")) {
	mode = 0; /* default mode */
	ret = test_fallocate(fd, mode, offset, len);
  	if (ret) {
		printf("test_fallocate: ERROR ! ret=%d\n", ret);
		goto out;
	}
	ret = test_write(fd, offset, len);
  	if (ret) printf("test_write: ERROR ! ret=%d\n", ret);
  } else {
        printf("%s: Invalid arguments.\n", argv[0]);
	usage(argv);
  }

out:

  if (!ret) printf("\n\n### TESTS PASSED ###\n");
  else printf("\n\n#!# TESTS FAILED #!#\n");

  close(fd);
  return ret;
}

[PATCH 1/5][TAKE8] manpage for fallocate

[Amit K. Arora]

Following is the modified version of the manpage originally submitted by
David Chinner. Please use `nroff -man fallocate.2 | less` to view.

Following changed from TAKE7:
* Removed FALLOC_ALLOCATE and FALLOCATE_RESV_SPACE modes.
* Described only single flag for mode, i.e. FALLOC_FL_KEEP_SIZE.
* s/zero blocks/zeroed blocks/ as suggested by Dave.
* Included <linux/falloc.h> instead of <fcntl.h>.

Following changed from TAKE6 to TAKE7:
Included changes suggested by Heikki Orsila and Barry Naujok.


.TH fallocate 2
.SH NAME
fallocate \- manipulate file space
.SH SYNOPSIS
.nf
.B #include <linux/falloc.h>
.PP
.BI "long fallocate(int " fd ", int " mode ", loff_t " offset ", loff_t " len ");
.SH DESCRIPTION
The
.B fallocate
syscall allows a user to directly manipulate the allocated disk space
for the file referred to by
.I fd
for the byte range starting at
.I offset
and continuing for
.I len
bytes.
The
.I mode
parameter determines the operation to be performed on the given range.
Currently there is only one flag supported for the mode argument.
.TP
.B FALLOC_FL_KEEP_SIZE
allocates and initialises to zero the disk space within the given range.
After a successful call, subsequent writes are guaranteed not to fail because
of lack of disk space.  Even if the size of the file is less than
.IR offset + len ,
the file size is not changed. This allows allocation of zeroed blocks beyond
the end of file and is useful for optimising append workloads.
.PP
If
.B FALLOC_FL_KEEP_SIZE
flag is not specified in the mode argument, the default behavior of this system
call is almost same as when this flag is passed. The only difference is that
on success, the file size will be changed if the
.IR offset + len
is greater than the file size. This default behavior closely resembles
.BR posix_fallocate (3)
and is intended as a method of optimally implementing this function.
.PP
.B fallocate
may allocate a larger range than that was specified.
.SH RETURN VALUE
.B fallocate
returns zero on success, or an error number on failure.
Note that
.I errno
is not set.
.SH ERRORS
.TP
.B EBADF
.I fd
is not a valid file descriptor, or is not opened for writing.
.TP
.B EFBIG
.IR offset + len
exceeds the maximum file size.
.TP
.B EINVAL
.I offset
was less than 0, or
.I len
was less than or equal to 0.
.TP
.B ENODEV
.I fd
does not refer to a regular file or a directory.
.TP
.B ENOSPC
There is not enough space left on the device containing the file
referred to by
.IR fd .
.TP
.B ESPIPE
.I fd
refers to a pipe of file descriptor.
.TP
.B ENOSYS
The filesystem underlying the file descriptor does not support this
operation.
.TP
.B EINTR
A signal was caught during execution
.TP
.B EIO
An I/O error occurred while reading from or writing to a file system.
.TP
.B EOPNOTSUPP
The mode is not supported on the file descriptor.
.SH AVAILABILITY
The
.B fallocate
system call is available since 2.6.XX
.SH SEE ALSO
.BR posix_fallocate (3),
.BR posix_fadvise (3),
.BR ftruncate (3).

[PATCH 2/5][TAKE8] fallocate() implementation in i386, x86_64 and powerpc

[Amit K. Arora]

From: Amit Arora <aarora@in.ibm.com>

sys_fallocate() implementation on i386, x86_64 and powerpc

fallocate() is a new system call being proposed here which will allow
applications to preallocate space to any file(s) in a file system.
Each file system implementation that wants to use this feature will need
to support an inode operation called ->fallocate().
Applications can use this feature to avoid fragmentation to certain
level and thus get faster access speed. With preallocation, applications
also get a guarantee of space for particular file(s) - even if later the
the system becomes full.

Currently, glibc provides an interface called posix_fallocate() which
can be used for similar cause. Though this has the advantage of working
on all file systems, but it is quite slow (since it writes zeroes to
each block that has to be preallocated). Without a doubt, file systems
can do this more efficiently within the kernel, by implementing
the proposed fallocate() system call. It is expected that
posix_fallocate() will be modified to call this new system call first
and incase the kernel/filesystem does not implement it, it should fall
back to the current implementation of writing zeroes to the new blocks.
ToDos:
1. Implementation on other architectures (other than i386, x86_64,
   and ppc). Patches for s390(x) and ia64 are already available from
   previous posts, but it was decided that they should be added later
   once fallocate is in the mainline. Hence not including those patches
   in this take.
2. Changes to glibc,
   a) to support fallocate() system call
   b) to make posix_fallocate() and posix_fallocate64() call fallocate()

CHANGELOG:
---------
Following changed from TAKE7:
1. Added linux/falloc.h and moved FALLOC_FL_KEEP_SIZE flag to it.
2. Removed the two modes (FALLOC_ALLOCATE and FALLOC_RESV_SPACE).
3. Merged "revalidate write permissions" patch from David P. Quigley
   to this patch.
4. Deleted comment above sys_fallocate definition, as suggested by Christoph.


Signed-off-by: Amit Arora <aarora@in.ibm.com>

Index: linux-2.6.22/arch/i386/kernel/syscall_table.S
===================================================================
--- linux-2.6.22.orig/arch/i386/kernel/syscall_table.S
+++ linux-2.6.22/arch/i386/kernel/syscall_table.S
@@ -323,3 +323,4 @@ ENTRY(sys_call_table)
 	.long sys_signalfd
 	.long sys_timerfd
 	.long sys_eventfd
+	.long sys_fallocate
Index: linux-2.6.22/arch/powerpc/kernel/sys_ppc32.c
===================================================================
--- linux-2.6.22.orig/arch/powerpc/kernel/sys_ppc32.c
+++ linux-2.6.22/arch/powerpc/kernel/sys_ppc32.c
@@ -773,6 +773,13 @@ asmlinkage int compat_sys_truncate64(con
 	return sys_truncate(path, (high << 32) | low);
 }
 
+asmlinkage long compat_sys_fallocate(int fd, int mode, u32 offhi, u32 offlo,
+				     u32 lenhi, u32 lenlo)
+{
+	return sys_fallocate(fd, mode, ((loff_t)offhi << 32) | offlo,
+			     ((loff_t)lenhi << 32) | lenlo);
+}
+
 asmlinkage int compat_sys_ftruncate64(unsigned int fd, u32 reg4, unsigned long high,
 				 unsigned long low)
 {
Index: linux-2.6.22/arch/x86_64/ia32/ia32entry.S
===================================================================
--- linux-2.6.22.orig/arch/x86_64/ia32/ia32entry.S
+++ linux-2.6.22/arch/x86_64/ia32/ia32entry.S
@@ -719,4 +719,5 @@ ia32_sys_call_table:
 	.quad compat_sys_signalfd
 	.quad compat_sys_timerfd
 	.quad sys_eventfd
+	.quad sys32_fallocate
 ia32_syscall_end:
Index: linux-2.6.22/fs/open.c
===================================================================
--- linux-2.6.22.orig/fs/open.c
+++ linux-2.6.22/fs/open.c
@@ -26,6 +26,7 @@
 #include <linux/syscalls.h>
 #include <linux/rcupdate.h>
 #include <linux/audit.h>
+#include <linux/falloc.h>
 
 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
@@ -352,6 +353,64 @@ asmlinkage long sys_ftruncate64(unsigned
 }
 #endif
 
+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 && !(mode & FALLOC_FL_KEEP_SIZE))
+		goto out;
+
+	ret = -EBADF;
+	file = fget(fd);
+	if (!file)
+		goto out;
+	if (!(file->f_mode & FMODE_WRITE))
+		goto out_fput;
+	/*
+	 * Revalidate the write permissions, in case security policy has
+	 * changed since the files were opened.
+	 */
+	ret = security_file_permission(file, MAY_WRITE);
+	if (ret)
+		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 + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
+		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;
+}
+
 /*
  * 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-2.6.22/include/asm-i386/unistd.h
===================================================================
--- linux-2.6.22.orig/include/asm-i386/unistd.h
+++ linux-2.6.22/include/asm-i386/unistd.h
@@ -329,10 +329,11 @@
 #define __NR_signalfd		321
 #define __NR_timerfd		322
 #define __NR_eventfd		323
+#define __NR_fallocate		324
 
 #ifdef __KERNEL__
 
-#define NR_syscalls 324
+#define NR_syscalls 325
 
 #define __ARCH_WANT_IPC_PARSE_VERSION
 #define __ARCH_WANT_OLD_READDIR
Index: linux-2.6.22/include/asm-powerpc/systbl.h
===================================================================
--- linux-2.6.22.orig/include/asm-powerpc/systbl.h
+++ linux-2.6.22/include/asm-powerpc/systbl.h
@@ -308,6 +308,7 @@ COMPAT_SYS_SPU(move_pages)
 SYSCALL_SPU(getcpu)
 COMPAT_SYS(epoll_pwait)
 COMPAT_SYS_SPU(utimensat)
+COMPAT_SYS(fallocate)
 COMPAT_SYS_SPU(signalfd)
 COMPAT_SYS_SPU(timerfd)
 SYSCALL_SPU(eventfd)
Index: linux-2.6.22/include/asm-powerpc/unistd.h
===================================================================
--- linux-2.6.22.orig/include/asm-powerpc/unistd.h
+++ linux-2.6.22/include/asm-powerpc/unistd.h
@@ -331,10 +331,11 @@
 #define __NR_timerfd		306
 #define __NR_eventfd		307
 #define __NR_sync_file_range2	308
+#define __NR_fallocate		309
 
 #ifdef __KERNEL__
 
-#define __NR_syscalls		309
+#define __NR_syscalls		310
 
 #define __NR__exit __NR_exit
 #define NR_syscalls	__NR_syscalls
Index: linux-2.6.22/include/asm-x86_64/unistd.h
===================================================================
--- linux-2.6.22.orig/include/asm-x86_64/unistd.h
+++ linux-2.6.22/include/asm-x86_64/unistd.h
@@ -630,6 +630,8 @@ __SYSCALL(__NR_signalfd, sys_signalfd)
 __SYSCALL(__NR_timerfd, sys_timerfd)
 #define __NR_eventfd		284
 __SYSCALL(__NR_eventfd, sys_eventfd)
+#define __NR_fallocate		285
+__SYSCALL(__NR_fallocate, sys_fallocate)
 
 #ifndef __NO_STUBS
 #define __ARCH_WANT_OLD_READDIR
Index: linux-2.6.22/include/linux/fs.h
===================================================================
--- linux-2.6.22.orig/include/linux/fs.h
+++ linux-2.6.22/include/linux/fs.h
@@ -1138,6 +1138,8 @@ 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);
+	long (*fallocate)(struct inode *inode, int mode, loff_t offset,
+			  loff_t len);
 };
 
 struct seq_file;
Index: linux-2.6.22/include/linux/syscalls.h
===================================================================
--- linux-2.6.22.orig/include/linux/syscalls.h
+++ linux-2.6.22/include/linux/syscalls.h
@@ -610,6 +610,7 @@ asmlinkage long sys_signalfd(int ufd, si
 asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
 			    const struct itimerspec __user *utmr);
 asmlinkage long sys_eventfd(unsigned int count);
+asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
 
 int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
 
Index: linux-2.6.22/arch/x86_64/ia32/sys_ia32.c
===================================================================
--- linux-2.6.22.orig/arch/x86_64/ia32/sys_ia32.c
+++ linux-2.6.22/arch/x86_64/ia32/sys_ia32.c
@@ -879,3 +879,11 @@ asmlinkage long sys32_fadvise64(int fd, 
 	return sys_fadvise64_64(fd, ((u64)offset_hi << 32) | offset_lo,
 				len, advice);
 }
+
+asmlinkage long sys32_fallocate(int fd, int mode, unsigned offset_lo,
+				unsigned offset_hi, unsigned len_lo,
+				unsigned len_hi)
+{
+	return sys_fallocate(fd, mode, ((u64)offset_hi << 32) | offset_lo,
+			     ((u64)len_hi << 32) | len_lo);
+}
Index: linux-2.6.22/include/linux/falloc.h
===================================================================
--- /dev/null
+++ linux-2.6.22/include/linux/falloc.h
@@ -0,0 +1,6 @@
+#ifndef _FALLOC_H_
+#define _FALLOC_H_
+
+#define FALLOC_FL_KEEP_SIZE	0x01 /* default is extend size */
+
+#endif /* _FALLOC_H_ */

[PATCH 3/5][TAKE8] ext4: fallocate support in ext4

[Amit K. Arora]

From: Amit Arora <aarora@in.ibm.com>

fallocate support in ext4

This patch implements ->fallocate() inode operation in ext4. With this
patch users of ext4 file systems will be able to use fallocate() system
call for persistent preallocation. Current implementation only supports
preallocation for regular files (directories not supported as of date)
with extent maps. This patch does not support block-mapped files currently.
Only FALLOC_ALLOCATE and FALLOC_RESV_SPACE modes are being supported as of
now.

CHANGELOG:
---------
Following changed from TAKE7:
1. Removed usage of FALLOC_ALLOCATE and FALLOC_RESV_SPACE modes and
   used FALLOC_FL_KEEP_SIZE mode flag instead.
2. Included  <linux/falloc.h> new header file, which defines above flag.


Signed-off-by: Amit Arora <aarora@in.ibm.com>

Index: linux-2.6.22/fs/ext4/extents.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/extents.c
+++ linux-2.6.22/fs/ext4/extents.c
@@ -39,6 +39,7 @@
 #include <linux/quotaops.h>
 #include <linux/string.h>
 #include <linux/slab.h>
+#include <linux/falloc.h>
 #include <linux/ext4_fs_extents.h>
 #include <asm/uaccess.h>
 
@@ -282,7 +283,7 @@ static void ext4_ext_show_path(struct in
 		} else if (path->p_ext) {
 			ext_debug("  %d:%d:%llu ",
 				  le32_to_cpu(path->p_ext->ee_block),
-				  le16_to_cpu(path->p_ext->ee_len),
+				  ext4_ext_get_actual_len(path->p_ext),
 				  ext_pblock(path->p_ext));
 		} else
 			ext_debug("  []");
@@ -305,7 +306,7 @@ static void ext4_ext_show_leaf(struct in
 
 	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
 		ext_debug("%d:%d:%llu ", le32_to_cpu(ex->ee_block),
-			  le16_to_cpu(ex->ee_len), ext_pblock(ex));
+			  ext4_ext_get_actual_len(ex), ext_pblock(ex));
 	}
 	ext_debug("\n");
 }
@@ -425,7 +426,7 @@ ext4_ext_binsearch(struct inode *inode, 
 	ext_debug("  -> %d:%llu:%d ",
 			le32_to_cpu(path->p_ext->ee_block),
 			ext_pblock(path->p_ext),
-			le16_to_cpu(path->p_ext->ee_len));
+			ext4_ext_get_actual_len(path->p_ext));
 
 #ifdef CHECK_BINSEARCH
 	{
@@ -686,7 +687,7 @@ static int ext4_ext_split(handle_t *hand
 		ext_debug("move %d:%llu:%d in new leaf %llu\n",
 				le32_to_cpu(path[depth].p_ext->ee_block),
 				ext_pblock(path[depth].p_ext),
-				le16_to_cpu(path[depth].p_ext->ee_len),
+				ext4_ext_get_actual_len(path[depth].p_ext),
 				newblock);
 		/*memmove(ex++, path[depth].p_ext++,
 				sizeof(struct ext4_extent));
@@ -1106,7 +1107,19 @@ static int
 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
 				struct ext4_extent *ex2)
 {
-	if (le32_to_cpu(ex1->ee_block) + le16_to_cpu(ex1->ee_len) !=
+	unsigned short ext1_ee_len, ext2_ee_len;
+
+	/*
+	 * Make sure that either both extents are uninitialized, or
+	 * both are _not_.
+	 */
+	if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
+		return 0;
+
+	ext1_ee_len = ext4_ext_get_actual_len(ex1);
+	ext2_ee_len = ext4_ext_get_actual_len(ex2);
+
+	if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
 			le32_to_cpu(ex2->ee_block))
 		return 0;
 
@@ -1115,14 +1128,14 @@ ext4_can_extents_be_merged(struct inode 
 	 * as an RO_COMPAT feature, refuse to merge to extents if
 	 * this can result in the top bit of ee_len being set.
 	 */
-	if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
+	if (ext1_ee_len + ext2_ee_len > EXT_MAX_LEN)
 		return 0;
 #ifdef AGGRESSIVE_TEST
 	if (le16_to_cpu(ex1->ee_len) >= 4)
 		return 0;
 #endif
 
-	if (ext_pblock(ex1) + le16_to_cpu(ex1->ee_len) == ext_pblock(ex2))
+	if (ext_pblock(ex1) + ext1_ee_len == ext_pblock(ex2))
 		return 1;
 	return 0;
 }
@@ -1144,7 +1157,7 @@ unsigned int ext4_ext_check_overlap(stru
 	unsigned int ret = 0;
 
 	b1 = le32_to_cpu(newext->ee_block);
-	len1 = le16_to_cpu(newext->ee_len);
+	len1 = ext4_ext_get_actual_len(newext);
 	depth = ext_depth(inode);
 	if (!path[depth].p_ext)
 		goto out;
@@ -1191,8 +1204,9 @@ int ext4_ext_insert_extent(handle_t *han
 	struct ext4_extent *nearex; /* nearest extent */
 	struct ext4_ext_path *npath = NULL;
 	int depth, len, err, next;
+	unsigned uninitialized = 0;
 
-	BUG_ON(newext->ee_len == 0);
+	BUG_ON(ext4_ext_get_actual_len(newext) == 0);
 	depth = ext_depth(inode);
 	ex = path[depth].p_ext;
 	BUG_ON(path[depth].p_hdr == NULL);
@@ -1200,14 +1214,24 @@ int ext4_ext_insert_extent(handle_t *han
 	/* try to insert block into found extent and return */
 	if (ex && ext4_can_extents_be_merged(inode, ex, newext)) {
 		ext_debug("append %d block to %d:%d (from %llu)\n",
-				le16_to_cpu(newext->ee_len),
+				ext4_ext_get_actual_len(newext),
 				le32_to_cpu(ex->ee_block),
-				le16_to_cpu(ex->ee_len), ext_pblock(ex));
+				ext4_ext_get_actual_len(ex), ext_pblock(ex));
 		err = ext4_ext_get_access(handle, inode, path + depth);
 		if (err)
 			return err;
-		ex->ee_len = cpu_to_le16(le16_to_cpu(ex->ee_len)
-					 + le16_to_cpu(newext->ee_len));
+
+		/*
+		 * ext4_can_extents_be_merged should have checked that either
+		 * both extents are uninitialized, or both aren't. Thus we
+		 * need to check only one of them here.
+		 */
+		if (ext4_ext_is_uninitialized(ex))
+			uninitialized = 1;
+		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
+					+ ext4_ext_get_actual_len(newext));
+		if (uninitialized)
+			ext4_ext_mark_uninitialized(ex);
 		eh = path[depth].p_hdr;
 		nearex = ex;
 		goto merge;
@@ -1263,7 +1287,7 @@ has_space:
 		ext_debug("first extent in the leaf: %d:%llu:%d\n",
 				le32_to_cpu(newext->ee_block),
 				ext_pblock(newext),
-				le16_to_cpu(newext->ee_len));
+				ext4_ext_get_actual_len(newext));
 		path[depth].p_ext = EXT_FIRST_EXTENT(eh);
 	} else if (le32_to_cpu(newext->ee_block)
 			   > le32_to_cpu(nearex->ee_block)) {
@@ -1276,7 +1300,7 @@ has_space:
 					"move %d from 0x%p to 0x%p\n",
 					le32_to_cpu(newext->ee_block),
 					ext_pblock(newext),
-					le16_to_cpu(newext->ee_len),
+					ext4_ext_get_actual_len(newext),
 					nearex, len, nearex + 1, nearex + 2);
 			memmove(nearex + 2, nearex + 1, len);
 		}
@@ -1289,7 +1313,7 @@ has_space:
 				"move %d from 0x%p to 0x%p\n",
 				le32_to_cpu(newext->ee_block),
 				ext_pblock(newext),
-				le16_to_cpu(newext->ee_len),
+				ext4_ext_get_actual_len(newext),
 				nearex, len, nearex + 1, nearex + 2);
 		memmove(nearex + 1, nearex, len);
 		path[depth].p_ext = nearex;
@@ -1308,8 +1332,13 @@ merge:
 		if (!ext4_can_extents_be_merged(inode, nearex, nearex + 1))
 			break;
 		/* merge with next extent! */
-		nearex->ee_len = cpu_to_le16(le16_to_cpu(nearex->ee_len)
-					     + le16_to_cpu(nearex[1].ee_len));
+		if (ext4_ext_is_uninitialized(nearex))
+			uninitialized = 1;
+		nearex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(nearex)
+					+ ext4_ext_get_actual_len(nearex + 1));
+		if (uninitialized)
+			ext4_ext_mark_uninitialized(nearex);
+
 		if (nearex + 1 < EXT_LAST_EXTENT(eh)) {
 			len = (EXT_LAST_EXTENT(eh) - nearex - 1)
 					* sizeof(struct ext4_extent);
@@ -1379,8 +1408,8 @@ int ext4_ext_walk_space(struct inode *in
 			end = le32_to_cpu(ex->ee_block);
 			if (block + num < end)
 				end = block + num;
-		} else if (block >=
-			     le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len)) {
+		} else if (block >= le32_to_cpu(ex->ee_block)
+					+ ext4_ext_get_actual_len(ex)) {
 			/* need to allocate space after found extent */
 			start = block;
 			end = block + num;
@@ -1392,7 +1421,8 @@ int ext4_ext_walk_space(struct inode *in
 			 * by found extent
 			 */
 			start = block;
-			end = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len);
+			end = le32_to_cpu(ex->ee_block)
+				+ ext4_ext_get_actual_len(ex);
 			if (block + num < end)
 				end = block + num;
 			exists = 1;
@@ -1408,7 +1438,7 @@ int ext4_ext_walk_space(struct inode *in
 			cbex.ec_type = EXT4_EXT_CACHE_GAP;
 		} else {
 			cbex.ec_block = le32_to_cpu(ex->ee_block);
-			cbex.ec_len = le16_to_cpu(ex->ee_len);
+			cbex.ec_len = ext4_ext_get_actual_len(ex);
 			cbex.ec_start = ext_pblock(ex);
 			cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
 		}
@@ -1481,15 +1511,15 @@ ext4_ext_put_gap_in_cache(struct inode *
 		ext_debug("cache gap(before): %lu [%lu:%lu]",
 				(unsigned long) block,
 				(unsigned long) le32_to_cpu(ex->ee_block),
-				(unsigned long) le16_to_cpu(ex->ee_len));
+				(unsigned long) ext4_ext_get_actual_len(ex));
 	} else if (block >= le32_to_cpu(ex->ee_block)
-			    + le16_to_cpu(ex->ee_len)) {
+			+ ext4_ext_get_actual_len(ex)) {
 		lblock = le32_to_cpu(ex->ee_block)
-			 + le16_to_cpu(ex->ee_len);
+			+ ext4_ext_get_actual_len(ex);
 		len = ext4_ext_next_allocated_block(path);
 		ext_debug("cache gap(after): [%lu:%lu] %lu",
 				(unsigned long) le32_to_cpu(ex->ee_block),
-				(unsigned long) le16_to_cpu(ex->ee_len),
+				(unsigned long) ext4_ext_get_actual_len(ex),
 				(unsigned long) block);
 		BUG_ON(len == lblock);
 		len = len - lblock;
@@ -1619,12 +1649,12 @@ static int ext4_remove_blocks(handle_t *
 				unsigned long from, unsigned long to)
 {
 	struct buffer_head *bh;
+	unsigned short ee_len =  ext4_ext_get_actual_len(ex);
 	int i;
 
 #ifdef EXTENTS_STATS
 	{
 		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-		unsigned short ee_len =  le16_to_cpu(ex->ee_len);
 		spin_lock(&sbi->s_ext_stats_lock);
 		sbi->s_ext_blocks += ee_len;
 		sbi->s_ext_extents++;
@@ -1638,12 +1668,12 @@ static int ext4_remove_blocks(handle_t *
 	}
 #endif
 	if (from >= le32_to_cpu(ex->ee_block)
-	    && to == le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
+	    && to == le32_to_cpu(ex->ee_block) + ee_len - 1) {
 		/* tail removal */
 		unsigned long num;
 		ext4_fsblk_t start;
-		num = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - from;
-		start = ext_pblock(ex) + le16_to_cpu(ex->ee_len) - num;
+		num = le32_to_cpu(ex->ee_block) + ee_len - from;
+		start = ext_pblock(ex) + ee_len - num;
 		ext_debug("free last %lu blocks starting %llu\n", num, start);
 		for (i = 0; i < num; i++) {
 			bh = sb_find_get_block(inode->i_sb, start + i);
@@ -1651,12 +1681,12 @@ static int ext4_remove_blocks(handle_t *
 		}
 		ext4_free_blocks(handle, inode, start, num);
 	} else if (from == le32_to_cpu(ex->ee_block)
-		   && to <= le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
+		   && to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
 		printk("strange request: removal %lu-%lu from %u:%u\n",
-		       from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
+			from, to, le32_to_cpu(ex->ee_block), ee_len);
 	} else {
 		printk("strange request: removal(2) %lu-%lu from %u:%u\n",
-		       from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
+			from, to, le32_to_cpu(ex->ee_block), ee_len);
 	}
 	return 0;
 }
@@ -1671,6 +1701,7 @@ ext4_ext_rm_leaf(handle_t *handle, struc
 	unsigned a, b, block, num;
 	unsigned long ex_ee_block;
 	unsigned short ex_ee_len;
+	unsigned uninitialized = 0;
 	struct ext4_extent *ex;
 
 	ext_debug("truncate since %lu in leaf\n", start);
@@ -1685,7 +1716,9 @@ ext4_ext_rm_leaf(handle_t *handle, struc
 	ex = EXT_LAST_EXTENT(eh);
 
 	ex_ee_block = le32_to_cpu(ex->ee_block);
-	ex_ee_len = le16_to_cpu(ex->ee_len);
+	if (ext4_ext_is_uninitialized(ex))
+		uninitialized = 1;
+	ex_ee_len = ext4_ext_get_actual_len(ex);
 
 	while (ex >= EXT_FIRST_EXTENT(eh) &&
 			ex_ee_block + ex_ee_len > start) {
@@ -1753,6 +1786,8 @@ ext4_ext_rm_leaf(handle_t *handle, struc
 
 		ex->ee_block = cpu_to_le32(block);
 		ex->ee_len = cpu_to_le16(num);
+		if (uninitialized)
+			ext4_ext_mark_uninitialized(ex);
 
 		err = ext4_ext_dirty(handle, inode, path + depth);
 		if (err)
@@ -1762,7 +1797,7 @@ ext4_ext_rm_leaf(handle_t *handle, struc
 				ext_pblock(ex));
 		ex--;
 		ex_ee_block = le32_to_cpu(ex->ee_block);
-		ex_ee_len = le16_to_cpu(ex->ee_len);
+		ex_ee_len = ext4_ext_get_actual_len(ex);
 	}
 
 	if (correct_index && eh->eh_entries)
@@ -2038,7 +2073,7 @@ int ext4_ext_get_blocks(handle_t *handle
 	if (ex) {
 		unsigned long ee_block = le32_to_cpu(ex->ee_block);
 		ext4_fsblk_t ee_start = ext_pblock(ex);
-		unsigned short ee_len  = le16_to_cpu(ex->ee_len);
+		unsigned short ee_len;
 
 		/*
 		 * Allow future support for preallocated extents to be added
@@ -2046,8 +2081,9 @@ int ext4_ext_get_blocks(handle_t *handle
 		 * Uninitialized extents are treated as holes, except that
 		 * we avoid (fail) allocating new blocks during a write.
 		 */
-		if (ee_len > EXT_MAX_LEN)
+		if (le16_to_cpu(ex->ee_len) > EXT_MAX_LEN)
 			goto out2;
+		ee_len = ext4_ext_get_actual_len(ex);
 		/* if found extent covers block, simply return it */
 		if (iblock >= ee_block && iblock < ee_block + ee_len) {
 			newblock = iblock - ee_block + ee_start;
@@ -2055,8 +2091,11 @@ int ext4_ext_get_blocks(handle_t *handle
 			allocated = ee_len - (iblock - ee_block);
 			ext_debug("%d fit into %lu:%d -> %llu\n", (int) iblock,
 					ee_block, ee_len, newblock);
-			ext4_ext_put_in_cache(inode, ee_block, ee_len,
-						ee_start, EXT4_EXT_CACHE_EXTENT);
+			/* Do not put uninitialized extent in the cache */
+			if (!ext4_ext_is_uninitialized(ex))
+				ext4_ext_put_in_cache(inode, ee_block,
+							ee_len, ee_start,
+							EXT4_EXT_CACHE_EXTENT);
 			goto out;
 		}
 	}
@@ -2098,6 +2137,8 @@ int ext4_ext_get_blocks(handle_t *handle
 	/* try to insert new extent into found leaf and return */
 	ext4_ext_store_pblock(&newex, newblock);
 	newex.ee_len = cpu_to_le16(allocated);
+	if (create == EXT4_CREATE_UNINITIALIZED_EXT)  /* Mark uninitialized */
+		ext4_ext_mark_uninitialized(&newex);
 	err = ext4_ext_insert_extent(handle, inode, path, &newex);
 	if (err) {
 		/* free data blocks we just allocated */
@@ -2113,8 +2154,10 @@ int ext4_ext_get_blocks(handle_t *handle
 	newblock = ext_pblock(&newex);
 	__set_bit(BH_New, &bh_result->b_state);
 
-	ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
-				EXT4_EXT_CACHE_EXTENT);
+	/* Cache only when it is _not_ an uninitialized extent */
+	if (create != EXT4_CREATE_UNINITIALIZED_EXT)
+		ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
+						EXT4_EXT_CACHE_EXTENT);
 out:
 	if (allocated > max_blocks)
 		allocated = max_blocks;
@@ -2217,3 +2260,127 @@ int ext4_ext_writepage_trans_blocks(stru
 
 	return needed;
 }
+
+/*
+ * preallocate space for a file. This implements ext4's fallocate inode
+ * operation, which gets called from sys_fallocate system call.
+ * For block-mapped files, posix_fallocate should fall back to the method
+ * of writing zeroes to the required new blocks (the same behavior which is
+ * expected for file systems which do not support fallocate() system call).
+ */
+long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
+{
+	handle_t *handle;
+	ext4_fsblk_t block, max_blocks;
+	ext4_fsblk_t nblocks = 0;
+	int ret = 0;
+	int ret2 = 0;
+	int retries = 0;
+	struct buffer_head map_bh;
+	unsigned int credits, blkbits = inode->i_blkbits;
+
+	/*
+	 * currently supporting (pre)allocate mode for extent-based
+	 * files _only_
+	 */
+	if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+		return -EOPNOTSUPP;
+
+	/* preallocation to directories is currently not supported */
+	if (S_ISDIR(inode->i_mode))
+		return -ENODEV;
+
+	block = offset >> blkbits;
+	max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
+			- block;
+
+	/*
+	 * credits to insert 1 extent into extent tree + buffers to be able to
+	 * modify 1 super block, 1 block bitmap and 1 group descriptor.
+	 */
+	credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
+retry:
+	while (ret >= 0 && ret < max_blocks) {
+		block = block + ret;
+		max_blocks = max_blocks - ret;
+		handle = ext4_journal_start(inode, credits);
+		if (IS_ERR(handle)) {
+			ret = PTR_ERR(handle);
+			break;
+		}
+
+		ret = ext4_ext_get_blocks(handle, inode, block,
+					  max_blocks, &map_bh,
+					  EXT4_CREATE_UNINITIALIZED_EXT, 0);
+		WARN_ON(!ret);
+		if (!ret) {
+			ext4_error(inode->i_sb, "ext4_fallocate",
+				   "ext4_ext_get_blocks returned 0! inode#%lu"
+				   ", block=%llu, max_blocks=%llu",
+				   inode->i_ino, block, max_blocks);
+			ret = -EIO;
+			ext4_mark_inode_dirty(handle, inode);
+			ret2 = ext4_journal_stop(handle);
+			break;
+		}
+		if (ret > 0) {
+			/* check wrap through sign-bit/zero here */
+			if ((block + ret) < 0 || (block + ret) < block) {
+				ret = -EIO;
+				ext4_mark_inode_dirty(handle, inode);
+				ret2 = ext4_journal_stop(handle);
+				break;
+			}
+			if (buffer_new(&map_bh) && ((block + ret) >
+			    (EXT4_BLOCK_ALIGN(i_size_read(inode), blkbits)
+			    >> blkbits)))
+					nblocks = nblocks + ret;
+		}
+
+		/* Update ctime if new blocks get allocated */
+		if (nblocks) {
+			struct timespec now;
+
+			now = current_fs_time(inode->i_sb);
+			if (!timespec_equal(&inode->i_ctime, &now))
+				inode->i_ctime = now;
+		}
+
+		ext4_mark_inode_dirty(handle, inode);
+		ret2 = ext4_journal_stop(handle);
+		if (ret2)
+			break;
+	}
+
+	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+		goto retry;
+
+	/*
+	 * Time to update the file size.
+	 * Update only when preallocation was requested beyond the file size.
+	 */
+	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+	    (offset + len) > i_size_read(inode)) {
+		if (ret > 0) {
+			/*
+			 * if no error, we assume preallocation succeeded
+			 * completely
+			 */
+			mutex_lock(&inode->i_mutex);
+			i_size_write(inode, offset + len);
+			EXT4_I(inode)->i_disksize = i_size_read(inode);
+			mutex_unlock(&inode->i_mutex);
+		} else if (ret < 0 && nblocks) {
+			/* Handle partial allocation scenario */
+			loff_t newsize;
+
+			mutex_lock(&inode->i_mutex);
+			newsize  = (nblocks << blkbits) + i_size_read(inode);
+			i_size_write(inode, EXT4_BLOCK_ALIGN(newsize, blkbits));
+			EXT4_I(inode)->i_disksize = i_size_read(inode);
+			mutex_unlock(&inode->i_mutex);
+		}
+	}
+
+	return ret > 0 ? ret2 : ret;
+}
Index: linux-2.6.22/fs/ext4/file.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/file.c
+++ linux-2.6.22/fs/ext4/file.c
@@ -135,5 +135,6 @@ const struct inode_operations ext4_file_
 	.removexattr	= generic_removexattr,
 #endif
 	.permission	= ext4_permission,
+	.fallocate	= ext4_fallocate,
 };
 
Index: linux-2.6.22/include/linux/ext4_fs.h
===================================================================
--- linux-2.6.22.orig/include/linux/ext4_fs.h
+++ linux-2.6.22/include/linux/ext4_fs.h
@@ -102,6 +102,7 @@
 				 EXT4_GOOD_OLD_FIRST_INO : \
 				 (s)->s_first_ino)
 #endif
+#define EXT4_BLOCK_ALIGN(size, blkbits)		ALIGN((size), (1 << (blkbits)))
 
 /*
  * Macro-instructions used to manage fragments
@@ -225,6 +226,11 @@ struct ext4_new_group_data {
 	__u32 free_blocks_count;
 };
 
+/*
+ * Following is used by preallocation code to tell get_blocks() that we
+ * want uninitialzed extents.
+ */
+#define EXT4_CREATE_UNINITIALIZED_EXT		2
 
 /*
  * ioctl commands
@@ -983,6 +989,8 @@ extern int ext4_ext_get_blocks(handle_t 
 extern void ext4_ext_truncate(struct inode *, struct page *);
 extern void ext4_ext_init(struct super_block *);
 extern void ext4_ext_release(struct super_block *);
+extern long ext4_fallocate(struct inode *inode, int mode, loff_t offset,
+			  loff_t len);
 static inline int
 ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
 			unsigned long max_blocks, struct buffer_head *bh,
Index: linux-2.6.22/include/linux/ext4_fs_extents.h
===================================================================
--- linux-2.6.22.orig/include/linux/ext4_fs_extents.h
+++ linux-2.6.22/include/linux/ext4_fs_extents.h
@@ -188,6 +188,21 @@ ext4_ext_invalidate_cache(struct inode *
 	EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
 }
 
+static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
+{
+	ext->ee_len |= cpu_to_le16(0x8000);
+}
+
+static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
+{
+	return (int)(le16_to_cpu((ext)->ee_len) & 0x8000);
+}
+
+static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
+{
+	return (int)(le16_to_cpu((ext)->ee_len) & 0x7FFF);
+}
+
 extern int ext4_extent_tree_init(handle_t *, struct inode *);
 extern int ext4_ext_calc_credits_for_insert(struct inode *, struct ext4_ext_path *);
 extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *);

[PATCH 4/5][TAKE8] ext4: write support for preallocated blocks

[Amit K. Arora]

From:  Amit Arora <aarora@in.ibm.com>

write support for preallocated blocks

This patch adds write support to the uninitialized extents that get
created when a preallocation is done using fallocate(). It takes care of
splitting the extents into multiple (upto three) extents and merging the
new split extents with neighbouring ones, if possible.

CHANGELOG:
---------
This patch did not change from TAKE7 (besides offsets ;).


Signed-off-by: Amit Arora <aarora@in.ibm.com>

Index: linux-2.6.22/fs/ext4/extents.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/extents.c
+++ linux-2.6.22/fs/ext4/extents.c
@@ -1141,6 +1141,53 @@ ext4_can_extents_be_merged(struct inode 
 }
 
 /*
+ * This function tries to merge the "ex" extent to the next extent in the tree.
+ * It always tries to merge towards right. If you want to merge towards
+ * left, pass "ex - 1" as argument instead of "ex".
+ * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
+ * 1 if they got merged.
+ */
+int ext4_ext_try_to_merge(struct inode *inode,
+			  struct ext4_ext_path *path,
+			  struct ext4_extent *ex)
+{
+	struct ext4_extent_header *eh;
+	unsigned int depth, len;
+	int merge_done = 0;
+	int uninitialized = 0;
+
+	depth = ext_depth(inode);
+	BUG_ON(path[depth].p_hdr == NULL);
+	eh = path[depth].p_hdr;
+
+	while (ex < EXT_LAST_EXTENT(eh)) {
+		if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
+			break;
+		/* merge with next extent! */
+		if (ext4_ext_is_uninitialized(ex))
+			uninitialized = 1;
+		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
+				+ ext4_ext_get_actual_len(ex + 1));
+		if (uninitialized)
+			ext4_ext_mark_uninitialized(ex);
+
+		if (ex + 1 < EXT_LAST_EXTENT(eh)) {
+			len = (EXT_LAST_EXTENT(eh) - ex - 1)
+				* sizeof(struct ext4_extent);
+			memmove(ex + 1, ex + 2, len);
+		}
+		eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries) - 1);
+		merge_done = 1;
+		WARN_ON(eh->eh_entries == 0);
+		if (!eh->eh_entries)
+			ext4_error(inode->i_sb, "ext4_ext_try_to_merge",
+			   "inode#%lu, eh->eh_entries = 0!", inode->i_ino);
+	}
+
+	return merge_done;
+}
+
+/*
  * check if a portion of the "newext" extent overlaps with an
  * existing extent.
  *
@@ -1328,25 +1375,7 @@ has_space:
 
 merge:
 	/* try to merge extents to the right */
-	while (nearex < EXT_LAST_EXTENT(eh)) {
-		if (!ext4_can_extents_be_merged(inode, nearex, nearex + 1))
-			break;
-		/* merge with next extent! */
-		if (ext4_ext_is_uninitialized(nearex))
-			uninitialized = 1;
-		nearex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(nearex)
-					+ ext4_ext_get_actual_len(nearex + 1));
-		if (uninitialized)
-			ext4_ext_mark_uninitialized(nearex);
-
-		if (nearex + 1 < EXT_LAST_EXTENT(eh)) {
-			len = (EXT_LAST_EXTENT(eh) - nearex - 1)
-					* sizeof(struct ext4_extent);
-			memmove(nearex + 1, nearex + 2, len);
-		}
-		eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
-		BUG_ON(eh->eh_entries == 0);
-	}
+	ext4_ext_try_to_merge(inode, path, nearex);
 
 	/* try to merge extents to the left */
 
@@ -2012,15 +2041,158 @@ void ext4_ext_release(struct super_block
 #endif
 }
 
+/*
+ * This function is called by ext4_ext_get_blocks() if someone tries to write
+ * to an uninitialized extent. It may result in splitting the uninitialized
+ * extent into multiple extents (upto three - one initialized and two
+ * uninitialized).
+ * There are three possibilities:
+ *   a> There is no split required: Entire extent should be initialized
+ *   b> Splits in two extents: Write is happening at either end of the extent
+ *   c> Splits in three extents: Somone is writing in middle of the extent
+ */
+int ext4_ext_convert_to_initialized(handle_t *handle, struct inode *inode,
+					struct ext4_ext_path *path,
+					ext4_fsblk_t iblock,
+					unsigned long max_blocks)
+{
+	struct ext4_extent *ex, newex;
+	struct ext4_extent *ex1 = NULL;
+	struct ext4_extent *ex2 = NULL;
+	struct ext4_extent *ex3 = NULL;
+	struct ext4_extent_header *eh;
+	unsigned int allocated, ee_block, ee_len, depth;
+	ext4_fsblk_t newblock;
+	int err = 0;
+	int ret = 0;
+
+	depth = ext_depth(inode);
+	eh = path[depth].p_hdr;
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+	allocated = ee_len - (iblock - ee_block);
+	newblock = iblock - ee_block + ext_pblock(ex);
+	ex2 = ex;
+
+	/* ex1: ee_block to iblock - 1 : uninitialized */
+	if (iblock > ee_block) {
+		ex1 = ex;
+		ex1->ee_len = cpu_to_le16(iblock - ee_block);
+		ext4_ext_mark_uninitialized(ex1);
+		ex2 = &newex;
+	}
+	/*
+	 * for sanity, update the length of the ex2 extent before
+	 * we insert ex3, if ex1 is NULL. This is to avoid temporary
+	 * overlap of blocks.
+	 */
+	if (!ex1 && allocated > max_blocks)
+		ex2->ee_len = cpu_to_le16(max_blocks);
+	/* ex3: to ee_block + ee_len : uninitialised */
+	if (allocated > max_blocks) {
+		unsigned int newdepth;
+		ex3 = &newex;
+		ex3->ee_block = cpu_to_le32(iblock + max_blocks);
+		ext4_ext_store_pblock(ex3, newblock + max_blocks);
+		ex3->ee_len = cpu_to_le16(allocated - max_blocks);
+		ext4_ext_mark_uninitialized(ex3);
+		err = ext4_ext_insert_extent(handle, inode, path, ex3);
+		if (err)
+			goto out;
+		/*
+		 * The depth, and hence eh & ex might change
+		 * as part of the insert above.
+		 */
+		newdepth = ext_depth(inode);
+		if (newdepth != depth) {
+			depth = newdepth;
+			path = ext4_ext_find_extent(inode, iblock, NULL);
+			if (IS_ERR(path)) {
+				err = PTR_ERR(path);
+				path = NULL;
+				goto out;
+			}
+			eh = path[depth].p_hdr;
+			ex = path[depth].p_ext;
+			if (ex2 != &newex)
+				ex2 = ex;
+		}
+		allocated = max_blocks;
+	}
+	/*
+	 * If there was a change of depth as part of the
+	 * insertion of ex3 above, we need to update the length
+	 * of the ex1 extent again here
+	 */
+	if (ex1 && ex1 != ex) {
+		ex1 = ex;
+		ex1->ee_len = cpu_to_le16(iblock - ee_block);
+		ext4_ext_mark_uninitialized(ex1);
+		ex2 = &newex;
+	}
+	/* ex2: iblock to iblock + maxblocks-1 : initialised */
+	ex2->ee_block = cpu_to_le32(iblock);
+	ex2->ee_start = cpu_to_le32(newblock);
+	ext4_ext_store_pblock(ex2, newblock);
+	ex2->ee_len = cpu_to_le16(allocated);
+	if (ex2 != ex)
+		goto insert;
+	err = ext4_ext_get_access(handle, inode, path + depth);
+	if (err)
+		goto out;
+	/*
+	 * New (initialized) extent starts from the first block
+	 * in the current extent. i.e., ex2 == ex
+	 * We have to see if it can be merged with the extent
+	 * on the left.
+	 */
+	if (ex2 > EXT_FIRST_EXTENT(eh)) {
+		/*
+		 * To merge left, pass "ex2 - 1" to try_to_merge(),
+		 * since it merges towards right _only_.
+		 */
+		ret = ext4_ext_try_to_merge(inode, path, ex2 - 1);
+		if (ret) {
+			err = ext4_ext_correct_indexes(handle, inode, path);
+			if (err)
+				goto out;
+			depth = ext_depth(inode);
+			ex2--;
+		}
+	}
+	/*
+	 * Try to Merge towards right. This might be required
+	 * only when the whole extent is being written to.
+	 * i.e. ex2 == ex and ex3 == NULL.
+	 */
+	if (!ex3) {
+		ret = ext4_ext_try_to_merge(inode, path, ex2);
+		if (ret) {
+			err = ext4_ext_correct_indexes(handle, inode, path);
+			if (err)
+				goto out;
+		}
+	}
+	/* Mark modified extent as dirty */
+	err = ext4_ext_dirty(handle, inode, path + depth);
+	goto out;
+insert:
+	err = ext4_ext_insert_extent(handle, inode, path, &newex);
+out:
+	return err ? err : allocated;
+}
+
 int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
 			ext4_fsblk_t iblock,
 			unsigned long max_blocks, struct buffer_head *bh_result,
 			int create, int extend_disksize)
 {
 	struct ext4_ext_path *path = NULL;
+	struct ext4_extent_header *eh;
 	struct ext4_extent newex, *ex;
 	ext4_fsblk_t goal, newblock;
-	int err = 0, depth;
+	int err = 0, depth, ret;
 	unsigned long allocated = 0;
 
 	__clear_bit(BH_New, &bh_result->b_state);
@@ -2033,8 +2205,10 @@ int ext4_ext_get_blocks(handle_t *handle
 	if (goal) {
 		if (goal == EXT4_EXT_CACHE_GAP) {
 			if (!create) {
-				/* block isn't allocated yet and
-				 * user doesn't want to allocate it */
+				/*
+				 * block isn't allocated yet and
+				 * user doesn't want to allocate it
+				 */
 				goto out2;
 			}
 			/* we should allocate requested block */
@@ -2068,6 +2242,7 @@ int ext4_ext_get_blocks(handle_t *handle
 	 * this is why assert can't be put in ext4_ext_find_extent()
 	 */
 	BUG_ON(path[depth].p_ext == NULL && depth != 0);
+	eh = path[depth].p_hdr;
 
 	ex = path[depth].p_ext;
 	if (ex) {
@@ -2076,13 +2251,9 @@ int ext4_ext_get_blocks(handle_t *handle
 		unsigned short ee_len;
 
 		/*
-		 * Allow future support for preallocated extents to be added
-		 * as an RO_COMPAT feature:
 		 * Uninitialized extents are treated as holes, except that
-		 * we avoid (fail) allocating new blocks during a write.
+		 * we split out initialized portions during a write.
 		 */
-		if (le16_to_cpu(ex->ee_len) > EXT_MAX_LEN)
-			goto out2;
 		ee_len = ext4_ext_get_actual_len(ex);
 		/* if found extent covers block, simply return it */
 		if (iblock >= ee_block && iblock < ee_block + ee_len) {
@@ -2091,12 +2262,27 @@ int ext4_ext_get_blocks(handle_t *handle
 			allocated = ee_len - (iblock - ee_block);
 			ext_debug("%d fit into %lu:%d -> %llu\n", (int) iblock,
 					ee_block, ee_len, newblock);
+
 			/* Do not put uninitialized extent in the cache */
-			if (!ext4_ext_is_uninitialized(ex))
+			if (!ext4_ext_is_uninitialized(ex)) {
 				ext4_ext_put_in_cache(inode, ee_block,
 							ee_len, ee_start,
 							EXT4_EXT_CACHE_EXTENT);
-			goto out;
+				goto out;
+			}
+			if (create == EXT4_CREATE_UNINITIALIZED_EXT)
+				goto out;
+			if (!create)
+				goto out2;
+
+			ret = ext4_ext_convert_to_initialized(handle, inode,
+								path, iblock,
+								max_blocks);
+			if (ret <= 0)
+				goto out2;
+			else
+				allocated = ret;
+			goto outnew;
 		}
 	}
 
@@ -2105,8 +2291,10 @@ int ext4_ext_get_blocks(handle_t *handle
 	 * we couldn't try to create block if create flag is zero
 	 */
 	if (!create) {
-		/* put just found gap into cache to speed up
-		 * subsequent requests */
+		/*
+		 * put just found gap into cache to speed up
+		 * subsequent requests
+		 */
 		ext4_ext_put_gap_in_cache(inode, path, iblock);
 		goto out2;
 	}
@@ -2152,6 +2340,7 @@ int ext4_ext_get_blocks(handle_t *handle
 
 	/* previous routine could use block we allocated */
 	newblock = ext_pblock(&newex);
+outnew:
 	__set_bit(BH_New, &bh_result->b_state);
 
 	/* Cache only when it is _not_ an uninitialized extent */
@@ -2221,7 +2410,8 @@ void ext4_ext_truncate(struct inode * in
 	err = ext4_ext_remove_space(inode, last_block);
 
 	/* In a multi-transaction truncate, we only make the final
-	 * transaction synchronous. */
+	 * transaction synchronous.
+	 */
 	if (IS_SYNC(inode))
 		handle->h_sync = 1;
 
Index: linux-2.6.22/include/linux/ext4_fs_extents.h
===================================================================
--- linux-2.6.22.orig/include/linux/ext4_fs_extents.h
+++ linux-2.6.22/include/linux/ext4_fs_extents.h
@@ -205,6 +205,9 @@ static inline int ext4_ext_get_actual_le
 
 extern int ext4_extent_tree_init(handle_t *, struct inode *);
 extern int ext4_ext_calc_credits_for_insert(struct inode *, struct ext4_ext_path *);
+extern int ext4_ext_try_to_merge(struct inode *inode,
+				 struct ext4_ext_path *path,
+				 struct ext4_extent *);
 extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *);
 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *);
 extern int ext4_ext_walk_space(struct inode *, unsigned long, unsigned long, ext_prepare_callback, void *);

[PATCH 5/5][TAKE8] ext4: change for better extent-to-group alignment

[Amit K. Arora]

From: Amit Arora <aarora@in.ibm.com>

Change on-disk format for extent to represent uninitialized/initialized extents

This change was suggested by Andreas Dilger. 
This patch changes the EXT_MAX_LEN value and extent code which marks/checks
uninitialized extents. With this change it will be possible to have
initialized extents with 2^15 blocks (earlier the max blocks we could have
was 2^15 - 1). This way we can have better extent-to-block alignment.
Now, maximum number of blocks we can have in an initialized extent is 2^15
and in an uninitialized extent is 2^15 - 1.


CHANGELOG:
---------
This patch did not change from TAKE7 (besides offsets ;).

Following changed from TAKE6 to TAKE7:
1. Taken care of Andreas's suggestion of using EXT_INIT_MAX_LEN instead of
   0x8000 at some places.

Signed-off-by: Amit Arora <aarora@in.ibm.com>

Index: linux-2.6.22/fs/ext4/extents.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/extents.c
+++ linux-2.6.22/fs/ext4/extents.c
@@ -1107,7 +1107,7 @@ static int
 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
 				struct ext4_extent *ex2)
 {
-	unsigned short ext1_ee_len, ext2_ee_len;
+	unsigned short ext1_ee_len, ext2_ee_len, max_len;
 
 	/*
 	 * Make sure that either both extents are uninitialized, or
@@ -1116,6 +1116,11 @@ ext4_can_extents_be_merged(struct inode 
 	if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
 		return 0;
 
+	if (ext4_ext_is_uninitialized(ex1))
+		max_len = EXT_UNINIT_MAX_LEN;
+	else
+		max_len = EXT_INIT_MAX_LEN;
+
 	ext1_ee_len = ext4_ext_get_actual_len(ex1);
 	ext2_ee_len = ext4_ext_get_actual_len(ex2);
 
@@ -1128,7 +1133,7 @@ ext4_can_extents_be_merged(struct inode 
 	 * as an RO_COMPAT feature, refuse to merge to extents if
 	 * this can result in the top bit of ee_len being set.
 	 */
-	if (ext1_ee_len + ext2_ee_len > EXT_MAX_LEN)
+	if (ext1_ee_len + ext2_ee_len > max_len)
 		return 0;
 #ifdef AGGRESSIVE_TEST
 	if (le16_to_cpu(ex1->ee_len) >= 4)
@@ -1815,7 +1820,11 @@ ext4_ext_rm_leaf(handle_t *handle, struc
 
 		ex->ee_block = cpu_to_le32(block);
 		ex->ee_len = cpu_to_le16(num);
-		if (uninitialized)
+		/*
+		 * Do not mark uninitialized if all the blocks in the
+		 * extent have been removed.
+		 */
+		if (uninitialized && num)
 			ext4_ext_mark_uninitialized(ex);
 
 		err = ext4_ext_dirty(handle, inode, path + depth);
@@ -2308,6 +2317,19 @@ int ext4_ext_get_blocks(handle_t *handle
 	/* allocate new block */
 	goal = ext4_ext_find_goal(inode, path, iblock);
 
+	/*
+	 * See if request is beyond maximum number of blocks we can have in
+	 * a single extent. For an initialized extent this limit is
+	 * EXT_INIT_MAX_LEN and for an uninitialized extent this limit is
+	 * EXT_UNINIT_MAX_LEN.
+	 */
+	if (max_blocks > EXT_INIT_MAX_LEN &&
+	    create != EXT4_CREATE_UNINITIALIZED_EXT)
+		max_blocks = EXT_INIT_MAX_LEN;
+	else if (max_blocks > EXT_UNINIT_MAX_LEN &&
+		 create == EXT4_CREATE_UNINITIALIZED_EXT)
+		max_blocks = EXT_UNINIT_MAX_LEN;
+
 	/* Check if we can really insert (iblock)::(iblock+max_blocks) extent */
 	newex.ee_block = cpu_to_le32(iblock);
 	newex.ee_len = cpu_to_le16(max_blocks);
Index: linux-2.6.22/include/linux/ext4_fs_extents.h
===================================================================
--- linux-2.6.22.orig/include/linux/ext4_fs_extents.h
+++ linux-2.6.22/include/linux/ext4_fs_extents.h
@@ -141,7 +141,25 @@ typedef int (*ext_prepare_callback)(stru
 
 #define EXT_MAX_BLOCK	0xffffffff
 
-#define EXT_MAX_LEN	((1UL << 15) - 1)
+/*
+ * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
+ * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
+ * MSB of ee_len field in the extent datastructure to signify if this
+ * particular extent is an initialized extent or an uninitialized (i.e.
+ * preallocated).
+ * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
+ * uninitialized extent.
+ * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
+ * uninitialized one. In other words, if MSB of ee_len is set, it is an
+ * uninitialized extent with only one special scenario when ee_len = 0x8000.
+ * In this case we can not have an uninitialized extent of zero length and
+ * thus we make it as a special case of initialized extent with 0x8000 length.
+ * This way we get better extent-to-group alignment for initialized extents.
+ * Hence, the maximum number of blocks we can have in an *initialized*
+ * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
+ */
+#define EXT_INIT_MAX_LEN	(1UL << 15)
+#define EXT_UNINIT_MAX_LEN	(EXT_INIT_MAX_LEN - 1)
 
 
 #define EXT_FIRST_EXTENT(__hdr__) \
@@ -190,17 +208,22 @@ ext4_ext_invalidate_cache(struct inode *
 
 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
 {
-	ext->ee_len |= cpu_to_le16(0x8000);
+	/* We can not have an uninitialized extent of zero length! */
+	BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
+	ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
 }
 
 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
 {
-	return (int)(le16_to_cpu((ext)->ee_len) & 0x8000);
+	/* Extent with ee_len of 0x8000 is treated as an initialized extent */
+	return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
 }
 
 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
 {
-	return (int)(le16_to_cpu((ext)->ee_len) & 0x7FFF);
+	return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
+		le16_to_cpu(ext->ee_len) :
+		(le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
 }
 
 extern int ext4_extent_tree_init(handle_t *, struct inode *);

[PATCH] ia64 fallocate system call

[David Chinner]

sys_fallocate for ia64. This uses the empty slot originally
reserved for move_pages.

Signed-Off-By: Dave Chinner <dgc@sgi.com>

---
 arch/ia64/kernel/entry.S  |    2 +-
 include/asm-ia64/unistd.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Index: 2.6.x-xfs-new/arch/ia64/kernel/entry.S
===================================================================
--- 2.6.x-xfs-new.orig/arch/ia64/kernel/entry.S	2007-07-16 14:18:51.432168485 +1000
+++ 2.6.x-xfs-new/arch/ia64/kernel/entry.S	2007-07-16 14:22:08.582454284 +1000
@@ -1581,7 +1581,7 @@ sys_call_table:
 	data8 sys_sync_file_range		// 1300
 	data8 sys_tee
 	data8 sys_vmsplice
-	data8 sys_ni_syscall			// reserved for move_pages
+	data8 sys_fallocate
 	data8 sys_getcpu
 	data8 sys_epoll_pwait			// 1305
 	data8 sys_utimensat
Index: 2.6.x-xfs-new/include/asm-ia64/unistd.h
===================================================================
--- 2.6.x-xfs-new.orig/include/asm-ia64/unistd.h	2007-06-08 21:36:31.000000000 +1000
+++ 2.6.x-xfs-new/include/asm-ia64/unistd.h	2007-07-16 14:22:41.166204402 +1000
@@ -292,7 +292,7 @@
 #define __NR_sync_file_range		1300
 #define __NR_tee			1301
 #define __NR_vmsplice			1302
-/* 1303 reserved for move_pages */
+#define __NR_fallocate			1303
 #define __NR_getcpu			1304
 #define __NR_epoll_pwait		1305
 #define __NR_utimensat			1306

[PATCH] xfs: implement fallocate V2

[David Chinner]

Initial implementation of ->fallocate for XFS.

Version 2:

o Make allocation and setting the file size atomic.
o Drop deallocate/punch functionality
o use mode field appropriately to determine if size needs changing.

---
 fs/xfs/linux-2.6/xfs_iops.c |   47 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_iops.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_iops.c	2007-07-16 14:16:02.090255611 +1000
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_iops.c	2007-07-16 14:50:07.087885337 +1000
@@ -51,6 +51,7 @@
 #include <linux/xattr.h>
 #include <linux/namei.h>
 #include <linux/security.h>
+#include <linux/falloc.h>
 
 /*
  * Get a XFS inode from a given vnode.
@@ -812,6 +813,51 @@ xfs_vn_removexattr(
 	return namesp->attr_remove(vp, attr, xflags);
 }
 
+/*
+ * generic space allocation vector.
+ *
+ * This should really through a bhv_vop before stuffing around
+ * with xfs_inodes and such.
+ */
+STATIC long
+xfs_vn_fallocate(
+	struct inode	*inode,
+	int		mode,
+	loff_t		offset,
+	loff_t		len)
+{
+	long		error = -EOPNOTSUPP;
+	bhv_vnode_t	*vp = vn_from_inode(inode);
+	bhv_desc_t	*bdp;
+	loff_t		new_size = 0;
+	xfs_flock64_t	bf;
+
+	bf.l_whence = 0;
+	bf.l_start = offset;
+	bf.l_len = len;
+
+	bdp = bhv_lookup_range(VN_BHV_HEAD(vp), VNODE_POSITION_XFS,
+						VNODE_POSITION_XFS);
+
+	xfs_ilock(xfs_vtoi(vp), XFS_IOLOCK_EXCL);
+	error = xfs_change_file_space(bdp, XFS_IOC_RESVSP, &bf, 0, NULL,
+							ATTR_NOLOCK);
+	if (!error && !(mode & FALLOC_FL_KEEP_SIZE) &&
+	    offset + len > i_size_read(inode))
+		new_size = offset + len;
+
+	/* Change file size if needed */
+	if (new_size) {
+		bhv_vattr_t	va;
+
+		va.va_mask = XFS_AT_SIZE;
+		va.va_size = new_size;
+		error = bhv_vop_setattr(vp, &va, ATTR_NOLOCK, NULL);
+	}
+
+	xfs_iunlock(xfs_vtoi(vp), XFS_IOLOCK_EXCL);
+	return error;
+}
 
 const struct inode_operations xfs_inode_operations = {
 	.permission		= xfs_vn_permission,
@@ -822,6 +868,7 @@ const struct inode_operations xfs_inode_
 	.getxattr		= xfs_vn_getxattr,
 	.listxattr		= xfs_vn_listxattr,
 	.removexattr		= xfs_vn_removexattr,
+	.fallocate		= xfs_vn_fallocate,
 };
 
 const struct inode_operations xfs_dir_inode_operations = {
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group

[PATCH] introduce fallocate support into xfs_io

[David Chinner]

FYI.

Initial support for fallocate-based pre-allocation in
xfs_io for testing. This currently only works on ia64 because
of the hard coded syscall number and will require autoconf
magic to conditionally compile in this support.

This allows simple command-line based testing of fallocate
based allocation such as:

# ~/xfs_io -f -c "falloc_resvsp 0 1024k" -c "bmap -vp" -c stat /mnt/scratch/fred
/mnt/scratch/fred:
 EXT: FILE-OFFSET      BLOCK-RANGE      AG AG-OFFSET        TOTAL FLAGS
   0: [0..2047]:       96..2143          0 (96..2143)        2048 10000
fd.path = "/mnt/scratch/fred"
fd.flags = non-sync,non-direct,read-write
stat.ino = 131
stat.type = regular file
stat.size = 0
stat.blocks = 2048
fsxattr.xflags = 0x2 [-p------------]
fsxattr.projid = 0
fsxattr.extsize = 0
fsxattr.nextents = 1
fsxattr.naextents = 0
dioattr.mem = 0x200
dioattr.miniosz = 512
dioattr.maxiosz = 2147483136

Or more complex cases:

# ~/xfs_io -f \
> -c "falloc_allocsp 0 1024k" \
> -c "unresvsp 32k 32k" \
> -c "unresvsp 128k 64k" \
> -c "unresvsp 512k 256k" \
> -c"pwrite 0 16k" \
> -c "pwrite 96k 128k" \
> -c "pwrite 640k 384k" \
> -c "bmap -vp" \
> -c "falloc_resvsp 0 1024k" \
> -c "bmap -vvp" /mnt/scratch/fred
wrote 16384/16384 bytes at offset 0
16 KiB, 4 ops; 0.0000 sec (274.123 MiB/sec and 70175.4386 ops/sec)
wrote 131072/131072 bytes at offset 98304
128 KiB, 32 ops; 0.0000 sec (338.753 MiB/sec and 86720.8672 ops/sec)
wrote 393216/393216 bytes at offset 655360
384 KiB, 96 ops; 0.0000 sec (386.200 MiB/sec and 98867.1473 ops/sec)
/mnt/scratch/fred:
 EXT: FILE-OFFSET      BLOCK-RANGE      AG AG-OFFSET        TOTAL FLAGS
   0: [0..31]:         96..127           0 (96..127)           32
   1: [32..63]:        128..159          0 (128..159)          32 10000
   2: [64..127]:       hole                                    64
   3: [128..191]:      224..287          0 (224..287)          64 10000
   4: [192..447]:      288..543          0 (288..543)         256
   5: [448..1023]:     544..1119         0 (544..1119)        576 10000
   6: [1024..1279]:    hole                                   256
   7: [1280..2047]:    1376..2143        0 (1376..2143)       768
/mnt/scratch/fred:
 EXT: FILE-OFFSET      BLOCK-RANGE      AG AG-OFFSET        TOTAL FLAGS
   0: [0..31]:         96..127           0 (96..127)           32
   1: [32..191]:       128..287          0 (128..287)         160 10000
   2: [192..447]:      288..543          0 (288..543)         256
   3: [448..1279]:     544..1375         0 (544..1375)        832 10000
   4: [1280..2047]:    1376..2143        0 (1376..2143)       768
 FLAG Values:
    010000 Unwritten preallocated extent
    001000 Doesn't begin on stripe unit
    000100 Doesn't end   on stripe unit
    000010 Doesn't begin on stripe width
    000001 Doesn't end   on stripe width

Yes, that looks like it filled all the holes properly, and the allocator
allocated the right holes on disk to merge adjacent extents when hole
filling. ;)

---
 xfsprogs/io/prealloc.c |   72 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

Index: xfs-cmds/xfsprogs/io/prealloc.c
===================================================================
--- xfs-cmds.orig/xfsprogs/io/prealloc.c	2006-11-15 19:00:31.000000000 +1100
+++ xfs-cmds/xfsprogs/io/prealloc.c	2007-07-16 15:25:44.041513574 +1000
@@ -26,6 +26,8 @@ static cmdinfo_t allocsp_cmd;
 static cmdinfo_t freesp_cmd;
 static cmdinfo_t resvsp_cmd;
 static cmdinfo_t unresvsp_cmd;
+static cmdinfo_t falloc_allocsp_cmd;
+static cmdinfo_t falloc_resvsp_cmd;
 
 static int
 offset_length(
@@ -119,6 +121,56 @@ unresvsp_f(
 	return 0;
 }
 
+/*
+ * Hack, hack, hackety-hack-hack.
+ *
+ * This only works for ia64...
+ */
+#define __NR_fallocate                1303
+
+/*
+ * someday there'll be a real header file
+ */
+#define FALLOC_FL_KEEP_SIZE     0x01
+#define FALLOC_ALLOCATE         0x0
+#define FALLOC_RESV_SPACE       FALLOC_FL_KEEP_SIZE
+
+static int
+fallocate_allocsp_f(
+	int		argc,
+	char		**argv)
+{
+	xfs_flock64_t	segment;
+
+	if (!offset_length(argv[1], argv[2], &segment))
+		return 0;
+
+	if (syscall(__NR_fallocate, file->fd, FALLOC_ALLOCATE,
+			segment.l_start, segment.l_len)) {
+		perror("FALLOC_ALLOCATE");
+		return 0;
+	}
+	return 0;
+}
+
+static int
+fallocate_resvsp_f(
+	int		argc,
+	char		**argv)
+{
+	xfs_flock64_t	segment;
+
+	if (!offset_length(argv[1], argv[2], &segment))
+		return 0;
+
+	if (syscall(__NR_fallocate, file->fd, FALLOC_RESV_SPACE,
+			segment.l_start, segment.l_len)) {
+		perror("FALLOC_ALLOCATE");
+		return 0;
+	}
+	return 0;
+}
+
 void
 prealloc_init(void)
 {
@@ -156,8 +208,28 @@ prealloc_init(void)
 	unresvsp_cmd.oneline =
 		_("frees reserved space associated with part of a file");
 
+	falloc_allocsp_cmd.name = _("falloc_allocsp");
+	falloc_allocsp_cmd.cfunc = fallocate_allocsp_f;
+	falloc_allocsp_cmd.argmin = 2;
+	falloc_allocsp_cmd.argmax = 2;
+	falloc_allocsp_cmd.flags = CMD_NOMAP_OK;
+	falloc_allocsp_cmd.args = _("off len");
+	falloc_allocsp_cmd.oneline =
+		_("allocates space associated with part of a file via fallocate");
+
+	falloc_resvsp_cmd.name = _("falloc_resvsp");
+	falloc_resvsp_cmd.cfunc = fallocate_resvsp_f;
+	falloc_resvsp_cmd.argmin = 2;
+	falloc_resvsp_cmd.argmax = 2;
+	falloc_resvsp_cmd.flags = CMD_NOMAP_OK;
+	falloc_resvsp_cmd.args = _("off len");
+	falloc_resvsp_cmd.oneline =
+		_("reserves space associated with part of a file via fallocate");
+
 	add_command(&allocsp_cmd);
 	add_command(&freesp_cmd);
 	add_command(&resvsp_cmd);
 	add_command(&unresvsp_cmd);
+	add_command(&falloc_allocsp_cmd);
+	add_command(&falloc_resvsp_cmd);
 }

Re: [PATCH 1/5][TAKE8] manpage for fallocate

[Mark Fasheh]

On Sat, Jul 14, 2007 at 12:16:25AM +0530, Amit K. Arora wrote:
> After a successful call, subsequent writes are guaranteed not to fail because
> of lack of disk space.
  
If a write to an unwritten region requires a node split, that could result
in the allocation of new meta data which obviously could fail if the disk is
truly full.

Granted that's unlikely to happen but maybe we should be conservative and
say something like:

"After a successful call, subsequent writes are guaranteed to never require
allocation of file data." ?
        --Mark

--
Mark Fasheh
Senior Software Developer, Oracle
mark.fasheh@oracle.com

Re: [PATCH 1/5][TAKE8] manpage for fallocate

[David Chinner]

On Wed, Jul 18, 2007 at 08:41:55PM -0700, Mark Fasheh wrote:
> On Sat, Jul 14, 2007 at 12:16:25AM +0530, Amit K. Arora wrote:
> > After a successful call, subsequent writes are guaranteed not to fail because
> > of lack of disk space.
>   
> If a write to an unwritten region requires a node split, that could result
> in the allocation of new meta data which obviously could fail if the disk is
> truly full.

% git-log 84e1e99f112dead8f9ba036c02d24a9f5ce7f544 |head -10
commit 84e1e99f112dead8f9ba036c02d24a9f5ce7f544
Author: David Chinner <dgc@sgi.com>
Date:   Mon Jun 18 16:50:27 2007 +1000

    [XFS] Prevent ENOSPC from aborting transactions that need to succeed

    During delayed allocation extent conversion or unwritten extent
    conversion, we need to reserve some blocks for transactions reservations.
    We need to reserve these blocks in case a btree split occurs and we need
    to allocate some blocks.

------

IOWs, XFS didn't provide this guarantee until about a month ago....

> Granted that's unlikely to happen but maybe we should be conservative and
> say something like:
> 
> "After a successful call, subsequent writes are guaranteed to never require
> allocation of file data." ?

Well, the above phrasing is taken directly from the posix_fallocate() man
page, and it is intended that sys_fallocate() is used to implement
posix_fallocate(). In that case, the semantics we have to provide are
"writes are guaranteed not to fail due to lack of disk space".

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group

Re: [PATCH 1/5][TAKE8] manpage for fallocate

[Mark Fasheh]

On Thu, Jul 19, 2007 at 03:10:52PM +1000, David Chinner wrote:
> % git-log 84e1e99f112dead8f9ba036c02d24a9f5ce7f544 |head -10
> commit 84e1e99f112dead8f9ba036c02d24a9f5ce7f544
> Author: David Chinner <dgc@sgi.com>
> Date:   Mon Jun 18 16:50:27 2007 +1000
> 
>     [XFS] Prevent ENOSPC from aborting transactions that need to succeed
> 
>     During delayed allocation extent conversion or unwritten extent
>     conversion, we need to reserve some blocks for transactions reservations.
>     We need to reserve these blocks in case a btree split occurs and we need
>     to allocate some blocks.
> 
> ------
> 
> IOWs, XFS didn't provide this guarantee until about a month ago....

Ok, once again XFS is ahead of the curve ;)

Comment rescinded then...
	--Mark

--
Mark Fasheh
Senior Software Developer, Oracle
mark.fasheh@oracle.com

Re: [PATCH 1/5][TAKE8] manpage for fallocate

[Andreas Dilger]

On Jul 18, 2007  20:41 -0700, Mark Fasheh wrote:
> On Sat, Jul 14, 2007 at 12:16:25AM +0530, Amit K. Arora wrote:
> > After a successful call, subsequent writes are guaranteed not to fail
> > because of lack of disk space.
>   
> If a write to an unwritten region requires a node split, that could result
> in the allocation of new meta data which obviously could fail if the disk is
> truly full.
> 
> Granted that's unlikely to happen but maybe we should be conservative and
> say something like:
> 
> "After a successful call, subsequent writes are guaranteed to never require
> allocation of file data." ?
>         --Mark

In the worst case, the unwritten extent could be zero-filled before the write
is done, so no exent split is needed.  We discussed this recently for the
ext4 fallocate, but didn't consider it important enough to hold the code.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.