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nilfs2: add ioctl which limits range of segment to be allocated

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This adds a new ioctl command which limits range of segment to be
allocated.  This is intended to gather data whithin a range of the
partition before shrinking the filesystem, or to control new log
location for some purpose.

If a range is specified by the ioctl, segment allocator of nilfs tries
to allocate new segments from the range unless no free segments are
available there.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi
2011-05-05 01:23:57 +09:00
parent 56eb553885
commit 619205da5b
4 changed files with 100 additions and 10 deletions
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73
fs/nilfs2/sufile.c
View File

@@ -33,7 +33,9 @@
struct nilfs_sufile_info {
struct nilfs_mdt_info mi;
unsigned long ncleansegs;
unsigned long ncleansegs;/* number of clean segments */
__u64 allocmin; /* lower limit of allocatable segment range */
__u64 allocmax; /* upper limit of allocatable segment range */
};
static inline struct nilfs_sufile_info *NILFS_SUI(struct inode *sufile)
@@ -247,6 +249,35 @@ int nilfs_sufile_update(struct inode *sufile, __u64 segnum, int create,
return ret;
}
/**
* nilfs_sufile_set_alloc_range - limit range of segment to be allocated
* @sufile: inode of segment usage file
* @start: minimum segment number of allocatable region (inclusive)
* @end: maximum segment number of allocatable region (inclusive)
*
* Return Value: On success, 0 is returned. On error, one of the
* following negative error codes is returned.
*
* %-ERANGE - invalid segment region
*/
int nilfs_sufile_set_alloc_range(struct inode *sufile, __u64 start, __u64 end)
{
struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
__u64 nsegs;
int ret = -ERANGE;
down_write(&NILFS_MDT(sufile)->mi_sem);
nsegs = nilfs_sufile_get_nsegments(sufile);
if (start <= end && end < nsegs) {
sui->allocmin = start;
sui->allocmax = end;
ret = 0;
}
up_write(&NILFS_MDT(sufile)->mi_sem);
return ret;
}
/**
* nilfs_sufile_alloc - allocate a segment
* @sufile: inode of segment usage file
@@ -269,11 +300,12 @@ int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
struct buffer_head *header_bh, *su_bh;
struct nilfs_sufile_header *header;
struct nilfs_segment_usage *su;
struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
size_t susz = NILFS_MDT(sufile)->mi_entry_size;
__u64 segnum, maxsegnum, last_alloc;
void *kaddr;
unsigned long nsegments, ncleansegs, nsus;
int ret, i, j;
unsigned long nsegments, ncleansegs, nsus, cnt;
int ret, j;
down_write(&NILFS_MDT(sufile)->mi_sem);
@@ -287,13 +319,31 @@ int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
kunmap_atomic(kaddr, KM_USER0);
nsegments = nilfs_sufile_get_nsegments(sufile);
maxsegnum = sui->allocmax;
segnum = last_alloc + 1;
maxsegnum = nsegments - 1;
for (i = 0; i < nsegments; i += nsus) {
if (segnum >= nsegments) {
/* wrap around */
segnum = 0;
maxsegnum = last_alloc;
if (segnum < sui->allocmin || segnum > sui->allocmax)
segnum = sui->allocmin;
for (cnt = 0; cnt < nsegments; cnt += nsus) {
if (segnum > maxsegnum) {
if (cnt < sui->allocmax - sui->allocmin + 1) {
/*
* wrap around in the limited region.
* if allocation started from
* sui->allocmin, this never happens.
*/
segnum = sui->allocmin;
maxsegnum = last_alloc;
} else if (segnum > sui->allocmin &&
sui->allocmax + 1 < nsegments) {
segnum = sui->allocmax + 1;
maxsegnum = nsegments - 1;
} else if (sui->allocmin > 0) {
segnum = 0;
maxsegnum = sui->allocmin - 1;
} else {
break; /* never happens */
}
}
ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 1,
&su_bh);
@@ -319,7 +369,7 @@ int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
header->sh_last_alloc = cpu_to_le64(segnum);
kunmap_atomic(kaddr, KM_USER0);
NILFS_SUI(sufile)->ncleansegs--;
sui->ncleansegs--;
nilfs_mdt_mark_buffer_dirty(header_bh);
nilfs_mdt_mark_buffer_dirty(su_bh);
nilfs_mdt_mark_dirty(sufile);
@@ -679,6 +729,9 @@ int nilfs_sufile_read(struct super_block *sb, size_t susize,
kunmap_atomic(kaddr, KM_USER0);
brelse(header_bh);
sui->allocmax = nilfs_sufile_get_nsegments(sufile) - 1;
sui->allocmin = 0;
unlock_new_inode(sufile);
out:
*inodep = sufile;