| Message ID | 20230824065634.2662858-1-srivathsa.d.dara@oracle.com |
|---|---|
| State | New |
| Headers | show |
| Series | [RESEND] debugfs/htree.c: In do_dx_hash() read hash_seed, hash_version directly from superblock | expand |
On Thu, Aug 24, 2023 at 06:56:34AM +0000, Srivathsa Dara wrote: > diff --git a/debugfs/htree.c b/debugfs/htree.c > index 7fae7f11..2d881c74 100644 > --- a/debugfs/htree.c > +++ b/debugfs/htree.c > @@ -316,7 +316,12 @@ void do_dx_hash(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)), > int hash_flags = 0; > const struct ext2fs_nls_table *encoding = NULL; > > - hash_seed[0] = hash_seed[1] = hash_seed[2] = hash_seed[3] = 0; > + hash_seed[0] = current_fs->super->s_hash_seed[0]; > + hash_seed[1] = current_fs->super->s_hash_seed[1]; > + hash_seed[2] = current_fs->super->s_hash_seed[2]; > + hash_seed[3] = current_fs->super->s_hash_seed[3]; > + > + hash_version = current_fs->super->s_def_hash_version; > > reset_getopt(); > while ((c = getopt(argc, argv, "h:s:ce:")) != EOF) { The problem with this patch is that if a file system is not opened, then current_fs is NULL. As a result: % gdb -q debugfs Reading symbols from debugfs... (gdb) run Starting program: /build/e2fsprogs/debugfs/debugfs [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". debugfs 1.47.0 (5-Feb-2023) debugfs: dx_hash test1 Program received signal SIGSEGV, Segmentation fault. 0x000055555556f73d in do_dx_hash (argc=2, argv=0x5555555d38d0, sci_idx=1, infop=0x0) at /usr/projects/e2fsprogs/e2fsprogs/debugfs/htree.c:343 343 hash_seed[0] = current_fs->super->s_hash_seed[0]; To address this, I've fixed up your patch slightly. (See below for the fix up, as well as the final patch.) Also, in the future, please make sure that the first line of the commit is a summary of the patch, no longer than 75 characters, and that the text is wrapped to no more than 75 characters. (I personally use 72 characters, but 75 is what suggested in the Linux Kernel's submitting patches documentation[1] in the "The Canonical Patch Format" section.) [1] https://docs.kernel.org/process/submitting-patches.html - Ted diff --git a/debugfs/htree.c b/debugfs/htree.c index ad493e8fb..a3e95ddb0 100644 --- a/debugfs/htree.c +++ b/debugfs/htree.c @@ -336,16 +336,18 @@ void do_dx_hash(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)), errcode_t err; int c; int hash_version = 0; - __u32 hash_seed[4]; + __u32 hash_seed[4] = { 0, }; int hash_flags = 0; const struct ext2fs_nls_table *encoding = NULL; - hash_seed[0] = current_fs->super->s_hash_seed[0]; - hash_seed[1] = current_fs->super->s_hash_seed[1]; - hash_seed[2] = current_fs->super->s_hash_seed[2]; - hash_seed[3] = current_fs->super->s_hash_seed[3]; + if (current_fs) { + hash_seed[0] = current_fs->super->s_hash_seed[0]; + hash_seed[1] = current_fs->super->s_hash_seed[1]; + hash_seed[2] = current_fs->super->s_hash_seed[2]; + hash_seed[3] = current_fs->super->s_hash_seed[3]; - hash_version = current_fs->super->s_def_hash_version; + hash_version = current_fs->super->s_def_hash_version; + } reset_getopt(); while ((c = getopt(argc, argv, "h:s:ce:")) != EOF) { commit 29d83fef9e6eab139516afe433c03d975e85c25b Author: Srivathsa Dara <srivathsa.d.dara@oracle.com> Date: Thu Aug 24 06:56:34 2023 +0000 debugfs: Use the hash_version from superblock if a file system is opened The debugfs program's dx_hash command computes the hash for the given filename, taking the hash_seed and hash_version (i.e hash algorithm) as arguments. So the user has to refer to the superblock to get these values used by the filesystem. So if debugfs has an opened file system, use those values from the current file system. [ Fixed patch to avoid crashing when a file system is not opened. --TYT ] Signed-off-by: Srivathsa Dara <srivathsa.d.dara@oracle.com> Link: https://lore.kernel.org/r/20230824065634.2662858-1-srivathsa.d.dara@oracle.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> diff --git a/debugfs/htree.c b/debugfs/htree.c index a9f9211ba..a3e95ddb0 100644 --- a/debugfs/htree.c +++ b/debugfs/htree.c @@ -336,11 +336,18 @@ void do_dx_hash(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)), errcode_t err; int c; int hash_version = 0; - __u32 hash_seed[4]; + __u32 hash_seed[4] = { 0, }; int hash_flags = 0; const struct ext2fs_nls_table *encoding = NULL; - hash_seed[0] = hash_seed[1] = hash_seed[2] = hash_seed[3] = 0; + if (current_fs) { + hash_seed[0] = current_fs->super->s_hash_seed[0]; + hash_seed[1] = current_fs->super->s_hash_seed[1]; + hash_seed[2] = current_fs->super->s_hash_seed[2]; + hash_seed[3] = current_fs->super->s_hash_seed[3]; + + hash_version = current_fs->super->s_def_hash_version; + } reset_getopt(); while ((c = getopt(argc, argv, "h:s:ce:")) != EOF) {
Hi Ted, Thank you for considering the patch and improving it. I'll make sure that I follow the proper patch formatting for my future patches. Thanks, Srivathsa Dara -----Original Message----- From: Theodore Ts'o <tytso@mit.edu> Sent: Sunday, December 3, 2023 10:45 AM To: Srivathsa Dara <srivathsa.d.dara@oracle.com> Cc: adilger.kernel@dilger.ca; linux-ext4@vger.kernel.org; Rajesh Sivaramasubramaniom <rajesh.sivaramasubramaniom@oracle.com>; Junxiao Bi <junxiao.bi@oracle.com> Subject: [External] : Re: [RESEND PATCH] debugfs/htree.c: In do_dx_hash() read hash_seed, hash_version directly from superblock On Thu, Aug 24, 2023 at 06:56:34AM +0000, Srivathsa Dara wrote: > diff --git a/debugfs/htree.c b/debugfs/htree.c index > 7fae7f11..2d881c74 100644 > --- a/debugfs/htree.c > +++ b/debugfs/htree.c > @@ -316,7 +316,12 @@ void do_dx_hash(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)), > int hash_flags = 0; > const struct ext2fs_nls_table *encoding = NULL; > > - hash_seed[0] = hash_seed[1] = hash_seed[2] = hash_seed[3] = 0; > + hash_seed[0] = current_fs->super->s_hash_seed[0]; > + hash_seed[1] = current_fs->super->s_hash_seed[1]; > + hash_seed[2] = current_fs->super->s_hash_seed[2]; > + hash_seed[3] = current_fs->super->s_hash_seed[3]; > + > + hash_version = current_fs->super->s_def_hash_version; > > reset_getopt(); > while ((c = getopt(argc, argv, "h:s:ce:")) != EOF) { The problem with this patch is that if a file system is not opened, then current_fs is NULL. As a result: % gdb -q debugfs Reading symbols from debugfs... (gdb) run Starting program: /build/e2fsprogs/debugfs/debugfs [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". debugfs 1.47.0 (5-Feb-2023) debugfs: dx_hash test1 Program received signal SIGSEGV, Segmentation fault. 0x000055555556f73d in do_dx_hash (argc=2, argv=0x5555555d38d0, sci_idx=1, infop=0x0) at /usr/projects/e2fsprogs/e2fsprogs/debugfs/htree.c:343 343 hash_seed[0] = current_fs->super->s_hash_seed[0]; To address this, I've fixed up your patch slightly. (See below for the fix up, as well as the final patch.) Also, in the future, please make sure that the first line of the commit is a summary of the patch, no longer than 75 characters, and that the text is wrapped to no more than 75 characters. (I personally use 72 characters, but 75 is what suggested in the Linux Kernel's submitting patches documentation[1] in the "The Canonical Patch Format" section.) [1] https://urldefense.com/v3/__https://docs.kernel.org/process/submitting-patches.html__;!!ACWV5N9M2RV99hQ!Pfb7MqoeE6NAhDDwRgjeGOuOZJ5NozX9970IvoER0R4oDpPXfKVMC3Mmq_TzfqTesrPbvRy6gI5sxFlEQo4$ - Ted
diff --git a/debugfs/htree.c b/debugfs/htree.c index 7fae7f11..2d881c74 100644 --- a/debugfs/htree.c +++ b/debugfs/htree.c @@ -316,7 +316,12 @@ void do_dx_hash(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)), int hash_flags = 0; const struct ext2fs_nls_table *encoding = NULL; - hash_seed[0] = hash_seed[1] = hash_seed[2] = hash_seed[3] = 0; + hash_seed[0] = current_fs->super->s_hash_seed[0]; + hash_seed[1] = current_fs->super->s_hash_seed[1]; + hash_seed[2] = current_fs->super->s_hash_seed[2]; + hash_seed[3] = current_fs->super->s_hash_seed[3]; + + hash_version = current_fs->super->s_def_hash_version; reset_getopt(); while ((c = getopt(argc, argv, "h:s:ce:")) != EOF) {
debugfs hash command computes the hash for the given filename. It takes hash_seed and hash_version (i.e hash algorithm) as arguments. User has to refer to the superblock to get these values used by the filesystem. If the arguments are not given then debugfs computes hash assuming both hash_seed and hash_version are zeros. In most of the cases this assumption will be different from the actual hash_seed and hash_version used by the filesystem. In general user will be in need of hash computed from hash_seed and hash_version of the filesystem. So, instead of assuming hash_seed and hash_version as zero when the arguments are not provided, read these directly from the superblock to simplify the task of user. Example: Before:- debugfs: hash -s 524e5394-e2a3-43fa-b192-79720b1fe3e1 -h half_md4 file1 Hash of file1 is 0x4a8d8c94 (minor 0x17a37f43) After improvement:- debugfs: hash file1 Hash of file1 is 0x4a8d8c94 (minor 0x17a37f43) Signed-off-by: Srivathsa Dara <srivathsa.d.dara@oracle.com> --- debugfs/htree.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)