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fiemap: also report end of current fragment
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@SeeSpotRun
SeeSpotRun committed May 12, 2015
1 parent cf89f21 commit f2b2d11
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Showing 3 changed files with 108 additions and 25 deletions.
6 changes: 3 additions & 3 deletions lib/shredder.c
View file
Expand Up @@ -871,7 +871,7 @@ static void rm_shred_file_get_start_offset(RmFile *file, RmSession *session) {
if(file->device->is_rotational && session->cfg->build_fiemap) {

RM_DEFINE_PATH(file);
file->current_fragment_physical_offset = rm_offset_get_from_path(file_path, 0);
file->current_fragment_physical_offset = rm_offset_get_from_path(file_path, 0, NULL);
rm_fmt_set_state(session->formats, RM_PROGRESS_STATE_PREPROCESS);

session->offsets_read++;
Expand Down Expand Up @@ -1606,7 +1606,7 @@ static void rm_shred_buffered_read_factory(RmFile *file, RmShredDevice *device)
buffer = rm_buffer_pool_get(device->main->mem_pool);
}
if (file->current_fragment_physical_offset > 0) {
file->current_fragment_physical_offset = rm_offset_get_from_fd(fileno(fd), file->seek_offset);
file->current_fragment_physical_offset = rm_offset_get_from_fd(fileno(fd), file->seek_offset, NULL);
}

if(ferror(fd) != 0) {
Expand Down Expand Up @@ -1726,7 +1726,7 @@ static void rm_shred_unbuffered_read_factory(RmFile *file, RmShredDevice *device
}

if (file->current_fragment_physical_offset > 0) {
file->current_fragment_physical_offset = rm_offset_get_from_fd(fd, file->seek_offset);
file->current_fragment_physical_offset = rm_offset_get_from_fd(fd, file->seek_offset, NULL);
}

if(bytes_read == -1) {
Expand Down
123 changes: 103 additions & 20 deletions lib/utilities.c
View file
Expand Up @@ -1068,46 +1068,129 @@ bool rm_mounts_can_reflink(RmMountTable *self, dev_t source, dev_t dest) {

#if HAVE_FIEMAP

RmOff rm_offset_get_from_fd(int fd, RmOff file_offset) {
/* TODO: add fake_fiemap option */
RmOff result=0;

/* Return fiemap structure containing n_extents for file descriptor fd.
* Return NULL if errors encountered.
* Needs to be freed with g_free if not NULL.
* */
static struct fiemap *rm_offset_get_fiemap(int fd, const int n_extents, const int file_offset){
/* struct fiemap does not allocate any extents by default,
* so we choose ourself how many of them we allocate.
* so we allocate the nominated number
* */
const int n_extents = 1;
struct fiemap *fiemap =
struct fiemap *fm =
g_malloc0(sizeof(struct fiemap) + n_extents * sizeof(struct fiemap_extent));
struct fiemap_extent *fm_ext = fiemap->fm_extents;

fiemap->fm_flags = 0;
fiemap->fm_extent_count = n_extents;
fiemap->fm_length = FIEMAP_MAX_OFFSET;
fiemap->fm_start = file_offset;
fm->fm_flags = 0;
fm->fm_extent_count = n_extents;
fm->fm_length = FIEMAP_MAX_OFFSET;
fm->fm_start = file_offset;

if(ioctl(fd, FS_IOC_FIEMAP, (unsigned long)fiemap) != -1 &&
fiemap->fm_mapped_extents > 0) {
result = fm_ext[0].fe_physical;
if(ioctl(fd, FS_IOC_FIEMAP, (unsigned long)fm) == -1) {
g_free(fm);
fm=NULL;
}
return fm;
}

/* Return physical (disk) offset of the beginning of the file extent containing the
* specified logical file_offset.
* If a pointer to file_offset_next is provided then read fiemap extents until
* the next non-contiguous extent (fragment) is encountered and writes the corresponding
* file offset to &file_offset_next.
* */
RmOff rm_offset_get_from_fd(int fd, const RmOff file_offset, RmOff *file_offset_next) {
/* TODO: add fake_fiemap option */
RmOff result=0;
bool done = FALSE;

/* used for detecting contiguous extents */
unsigned long expected = 0;

while (!done) {
/* read in one extent */
struct fiemap *fm = rm_offset_get_fiemap(fd, 1, file_offset);
if (!fm) {
done = TRUE;
} else {
if (!file_offset_next) {
/* no need to find end of fragment */
done = TRUE;
}
if (fm->fm_mapped_extents > 0) {
/* retrieve data from fiemap */
struct fiemap_extent *fm_ext = fm->fm_extents;
if (result == 0) {
/* this is the first extent */
result = fm_ext[0].fe_physical;
if (result==0) {
/* looks suspicious - let's get out of here */
done = TRUE;
}
} else if (fm_ext[0].fe_physical > expected ||
fm_ext[0].fe_physical < result) {
/* current extent is not contiguous with previous, so we can stop*/
done = TRUE;
if (file_offset_next) {
/* caller wants to know logical offset of next fragment */
*file_offset_next = fm_ext[0].fe_logical;
}
} else if (fm_ext[0].fe_flags & FIEMAP_EXTENT_LAST) {
done = TRUE;
if (file_offset_next) {
/* caller wants to know logical offset of next fragment - signal
* that it is EOF */
*file_offset_next = G_MAXUINT64;
}
}
if (!done) {
expected = fm_ext[0].fe_physical + fm_ext[0].fe_length;
}
}
g_free(fm);
}
}
g_free(fiemap);
return result;
}

RmOff rm_offset_get_from_path(const char *path, RmOff file_offset) {
RmOff rm_offset_get_from_path(const char *path, const RmOff file_offset, RmOff *file_offset_next) {
/* TODO: add fake_fiemap option */
int fd = rm_sys_open(path, O_RDONLY);
if(fd == -1) {
rm_log_info("Error opening %s in rm_offset_get_from_path\n", path);
return 0;
}
RmOff result=rm_offset_get_from_fd(fd, file_offset);
RmOff result=rm_offset_get_from_fd(fd, file_offset, file_offset_next);
rm_sys_close(fd);
return result;
}


bool rm_offsets_match(char *path1, char *path2) {
/* TODO */
return (path1 == path2);
bool result=FALSE;

int fd1 = rm_sys_open(path1, O_RDONLY);
if(fd1 != -1) {
int fd2 = rm_sys_open(path2, O_RDONLY);
if(fd2 != -1) {
RmOff file1_offset_next = 0;
RmOff file2_offset_next = 0;
while ( rm_offset_get_from_fd(fd1, file1_offset_next, &file1_offset_next) ==
rm_offset_get_from_fd(fd2, file2_offset_next, &file2_offset_next) &&
file1_offset_next != 0 &&
file1_offset_next == file2_offset_next ) {
if (file1_offset_next == G_MAXUINT64 || file2_offset_next == G_MAXUINT64) {
/* phew, we got to the end */
result = TRUE;
}
}
rm_sys_close(fd2);
} else {
rm_log_info("Error opening %s in rm_offsets_match\n", path2);
}
rm_sys_close(fd1);
} else {
rm_log_info("Error opening %s in rm_offsets_match\n", path1);
}
return result;
}

#else /* Probably FreeBSD */
Expand Down
4 changes: 2 additions & 2 deletions lib/utilities.h
View file
Expand Up @@ -301,14 +301,14 @@ bool rm_mounts_can_reflink(RmMountTable *self, dev_t source, dev_t dest);
*
* @return the physical offset starting from the disk.
*/
RmOff rm_offset_get_from_fd(int fd, RmOff file_offset);
RmOff rm_offset_get_from_fd(int fd, const RmOff file_offset, RmOff *file_offset_next);

/**
* @brief Lookup the physical offset of a file path at any given offset.
*
* @return the physical offset starting from the disk.
*/
RmOff rm_offset_get_from_path(const char *path, RmOff file_offset);
RmOff rm_offset_get_from_path(const char *path, const RmOff file_offset, RmOff *file_offset_next);

/**
* @brief Test if two files have identical fiemaps.
Expand Down

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