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Message-Id: <1205558133-27714-1-git-send-email-tytso@mit.edu>
Date: Sat, 15 Mar 2008 01:15:33 -0400
From: Theodore Ts'o <tytso@....edu>
To: Josef Bacik <jbacik@...hat.com>
Cc: linux-ext4@...r.kernel.org, Josef Bacik <jbacik@...hat.com>,
"Theodore Ts'o" <tytso@....edu>
Subject: [PATCH] resize2fs: Add options to print (and resizing to) the minimum filesystem size
From: Josef Bacik <jbacik@...hat.com>
Add the -P option to print the minimum filesystem size and exit.
Add the -M option to force resizing the filesystem to the minimum
filesystem size.
Signed-off-by: Josef Back <jbacik@...hat.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
resize/main.c | 29 +++++++---
resize/resize2fs.8.in | 47 +++++++++--------
resize/resize2fs.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++-
resize/resize2fs.h | 1 +
4 files changed, 185 insertions(+), 32 deletions(-)
diff --git a/resize/main.c b/resize/main.c
index f283e41..0cdda32 100644
--- a/resize/main.c
+++ b/resize/main.c
@@ -36,8 +36,8 @@ char *program_name, *device_name, *io_options;
static void usage (char *prog)
{
- fprintf (stderr, _("Usage: %s [-d debug_flags] [-f] [-F] [-p] "
- "device [new_size]\n\n"), prog);
+ fprintf (stderr, _("Usage: %s [-d debug_flags] [-f] [-F] [-M] [-P] "
+ "[-p] device [new_size]\n\n"), prog);
exit (1);
}
@@ -152,6 +152,8 @@ int main (int argc, char ** argv)
int flush = 0;
int force = 0;
int io_flags = 0;
+ int force_min_size = 0;
+ int print_min_size = 0;
int fd, ret;
blk_t new_size = 0;
blk_t max_size = 0;
@@ -183,7 +185,7 @@ int main (int argc, char ** argv)
if (argc && *argv)
program_name = *argv;
- while ((c = getopt (argc, argv, "d:fFhpS:")) != EOF) {
+ while ((c = getopt (argc, argv, "d:fFhMPpS:")) != EOF) {
switch (c) {
case 'h':
usage(program_name);
@@ -194,6 +196,12 @@ int main (int argc, char ** argv)
case 'F':
flush = 1;
break;
+ case 'M':
+ force_min_size = 1;
+ break;
+ case 'P':
+ print_min_size = 1;
+ break;
case 'd':
flags |= atoi(optarg);
break;
@@ -308,6 +316,12 @@ int main (int argc, char ** argv)
exit(1);
}
+ if (print_min_size) {
+ printf("Estimated minimum size of the filesystem: %lu\n",
+ calculate_minimum_resize_size(fs));
+ exit(0);
+ }
+
/* Determine the system page size if possible */
#ifdef HAVE_SYSCONF
#if (!defined(_SC_PAGESIZE) && defined(_SC_PAGE_SIZE))
@@ -332,14 +346,11 @@ int main (int argc, char ** argv)
_("while trying to determine filesystem size"));
exit(1);
}
- if (new_size_str) {
+ if (force_min_size)
+ new_size = calculate_minimum_resize_size(fs);
+ else if (new_size_str) {
new_size = parse_num_blocks(new_size_str,
fs->super->s_log_block_size);
- if (!new_size) {
- com_err(program_name, 0, _("bad filesystem size - %s"),
- new_size_str);
- exit(1);
- }
} else {
new_size = max_size;
/* Round down to an even multiple of a pagesize */
diff --git a/resize/resize2fs.8.in b/resize/resize2fs.8.in
index d43adad..7be4f04 100644
--- a/resize/resize2fs.8.in
+++ b/resize/resize2fs.8.in
@@ -8,6 +8,9 @@ resize2fs \- ext2/ext3 file system resizer
.SH SYNOPSIS
.B resize2fs
[
+.B \-fFpPM
+]
+[
.B \-d
.I debug-flags
]
@@ -15,15 +18,6 @@ resize2fs \- ext2/ext3 file system resizer
.B \-S
.I RAID-stride
]
-[
-.B \-f
-]
-[
-.B \-F
-]
-[
-.B \-p
-]
.I device
[
.I size
@@ -99,19 +93,6 @@ from the following list:
\ 8\ \-\ Debug inode relocations
.br
\ 16\ \-\ Debug moving the inode table
-.TP
-.B \-S \fIRAID-stride
-The
-.B resize2fs
-program will heuristically determine the RAID stride that was specified
-when the filesystem was created. This option allows the user to
-explicitly specify a RAID stride setting to be used by resize2fs instead.
-.TP
-.B \-p
-Prints out a percentage completion bars for each
-.B resize2fs
-operation, so that the user can keep track of what
-the program is doing.
.TP
.B \-f
Forces resize2fs to proceed with the filesystem resize operation, overriding
@@ -122,6 +103,28 @@ Flush the filesystem device's buffer caches before beginning. Only
really useful for doing
.B resize2fs
time trials.
+.TP
+.B \-M
+Shrink the filesystem to the minimum size.
+.TP
+.B \-p
+Prints out a percentage completion bars for each
+.B resize2fs
+operation, so that the user can keep track of what
+the program is doing.
+.TP
+.B \-P
+Print the minimum size of the filesystem and exit.
+.TP
+.B \-S \fIRAID-stride
+The
+.B resize2fs
+program will heuristically determine the RAID stride that was specified
+when the filesystem was created. This option allows the user to
+explicitly specify a RAID stride setting to be used by resize2fs instead.
+.SH KNOWN BUGS
+The minimum size of the filesystem as estimated by resize2fs may be
+incorrect, especially for filesystems with 1k and 2k blocksizes.
.SH AUTHOR
.B resize2fs
was written by Theodore Ts'o <tytso@....edu>.
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index da86ece..08dd413 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -63,7 +63,9 @@ static errcode_t ext2fs_calculate_summary_stats(ext2_filsys fs);
((blk) < (FS_INODE_TB((fs), (i)) + \
(fs)->inode_blocks_per_group)))
-
+#define META_OVERHEAD(fs) (2 + (fs)->inode_blocks_per_group)
+#define SUPER_OVERHEAD(fs) (1 + (fs)->desc_blocks +\
+ (fs)->super->s_reserved_gdt_blocks)
/*
* This is the top-level routine which does the dirty deed....
@@ -1620,3 +1622,139 @@ static errcode_t ext2fs_calculate_summary_stats(ext2_filsys fs)
ext2fs_mark_super_dirty(fs);
return 0;
}
+
+/*
+ * calcluate the minimum number of blocks the given fs can be resized to
+ */
+blk_t calculate_minimum_resize_size(ext2_filsys fs)
+{
+ blk_t inode_count, blks_needed, groups, blk, data_blocks;
+ blk_t grp, data_needed, last_start;
+ int overhead = 0, old_group = -1, num_of_superblocks = 0;
+
+ /*
+ * first figure out how many group descriptors we need to
+ * handle the number of inodes we have
+ */
+ inode_count = fs->super->s_inodes_count -
+ fs->super->s_free_inodes_count;
+ blks_needed = ext2fs_div_ceil(inode_count,
+ fs->super->s_inodes_per_group) *
+ EXT2_BLOCKS_PER_GROUP(fs->super);
+ groups = ext2fs_div_ceil(blks_needed,
+ EXT2_BLOCKS_PER_GROUP(fs->super));
+
+ /*
+ * we need to figure out how many backup superblocks we have so we can
+ * account for that in the metadata
+ */
+ for (grp = 0; grp < fs->group_desc_count; grp++) {
+ if (ext2fs_bg_has_super(fs, grp))
+ num_of_superblocks++;
+ }
+
+ /* calculate how many blocks are needed for data */
+ data_needed = fs->super->s_blocks_count -
+ fs->super->s_free_blocks_count;
+ data_needed -= SUPER_OVERHEAD(fs) * num_of_superblocks;
+ data_needed -= META_OVERHEAD(fs) * fs->group_desc_count;
+
+ /*
+ * figure out how many data blocks we have given the number of groups
+ * we need for our inodes
+ */
+ data_blocks = groups * EXT2_BLOCKS_PER_GROUP(fs->super);
+ last_start = 0;
+ for (grp = 0; grp < groups; grp++) {
+ overhead = META_OVERHEAD(fs);
+
+ if (ext2fs_bg_has_super(fs, grp))
+ overhead += SUPER_OVERHEAD(fs);
+
+ /*
+ * we want to keep track of how much data we can store in
+ * the groups leading up to the last group so we can determine
+ * how big the last group needs to be
+ */
+ if (grp != (groups - 1))
+ last_start += EXT2_BLOCKS_PER_GROUP(fs->super) -
+ overhead;
+
+ data_blocks -= overhead;
+ }
+
+ /*
+ * if we need more group descriptors in order to accomodate our data
+ * then we need to add them here
+ */
+ while (data_needed > data_blocks) {
+ blk_t remainder = data_needed - data_blocks;
+ blk_t extra_grps;
+
+ /* figure out how many more groups we need for the data */
+ extra_grps = ext2fs_div_ceil(remainder,
+ EXT2_BLOCKS_PER_GROUP(fs->super));
+
+ data_blocks += extra_grps * EXT2_BLOCKS_PER_GROUP(fs->super);
+
+ /* ok we have to account for the last group */
+ overhead = META_OVERHEAD(fs);
+ if (ext2fs_bg_has_super(fs, groups-1))
+ overhead += SUPER_OVERHEAD(fs);
+ last_start += EXT2_BLOCKS_PER_GROUP(fs->super) - overhead;
+
+ for (grp = groups; grp < groups+extra_grps; grp++) {
+ overhead = META_OVERHEAD(fs);
+ if (ext2fs_bg_has_super(fs, grp))
+ overhead += SUPER_OVERHEAD(fs);
+
+ /*
+ * again, we need to see how much data we cram into
+ * all of the groups leading up to the last group
+ */
+ if (grp != (groups + extra_grps - 1))
+ last_start += EXT2_BLOCKS_PER_GROUP(fs->super)
+ - overhead;
+
+ data_blocks -= overhead;
+ }
+
+ groups += extra_grps;
+ }
+
+ /* now for the fun voodoo */
+ overhead = META_OVERHEAD(fs);
+
+ /*
+ * if this is the case then the last group is going to have data in it
+ * so we need to adjust the size of the last group accordingly
+ */
+ if (last_start < data_needed) {
+ blk_t remainder = data_needed - last_start;
+
+ /*
+ * 50 is a magic number that mkfs/resize uses to see if its
+ * even worth making/resizing the fs. basically you need to
+ * have at least 50 blocks in addition to the blocks needed
+ * for the metadata in the last group
+ */
+ if (remainder > 50)
+ overhead += remainder;
+ else
+ overhead += 50;
+ } else
+ overhead += 50;
+
+ if (ext2fs_bg_has_super(fs, groups-1))
+ overhead += SUPER_OVERHEAD(fs);
+
+ /*
+ * since our last group doesn't have to be BLOCKS_PER_GROUP large, we
+ * only do groups-1, and then add the number of blocks needed to
+ * handle the group descriptor metadata+data that we need
+ */
+ blks_needed = (groups-1) * EXT2_BLOCKS_PER_GROUP(fs->super);
+ blks_needed += overhead;
+
+ return blks_needed;
+}
diff --git a/resize/resize2fs.h b/resize/resize2fs.h
index f87d04e..49b77d8 100644
--- a/resize/resize2fs.h
+++ b/resize/resize2fs.h
@@ -129,6 +129,7 @@ extern errcode_t resize_fs(ext2_filsys fs, blk_t *new_size, int flags,
extern errcode_t adjust_fs_info(ext2_filsys fs, ext2_filsys old_fs,
blk_t new_size);
+extern blk_t calculate_minimum_resize_size(ext2_filsys fs);
/* extent.c */
--
1.5.4.1.144.gdfee-dirty
--
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